{"title":"Astro-Tech","description":"Astro-Tech is Astronomics own brand of telescopes, focused providing high quality optical instruments ranging from compact refractors to large aperture astrographs.","products":[{"product_id":"astro-tech-10-f-8-truss-tube-ritchey-chretien-optical-tube","title":"Astro-Tech 10\" f\/8 Truss Tube Ritchey-Chrétien Optical Tube","description":"This newest Version A of the Astro-Tech AT10RCT carbon fiber Serrurier truss Ritchey-Chrétien \u003cstrong\u003e\u003cem\u003e\u003cspan style=\"color: #990000;\"\u003eHot Product for 2015\u003c\/span\u003e\u003c\/em\u003e\u003c\/strong\u003e makes high quality large-aperture\/large format DSLR and CCD imaging affordable for the dedicated amateur astrophotographer and educational institution.\u003chr\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis Astro-Tech AT10RCT Ritchey-Chrétien astrograph (named a Sky \u0026amp; Telescope Hot Product for 2015) has:\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 10\" f\/8 true Ritchey-Chrétien hyperbolic mirror optical design\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• carbon fiber truss tube design with CNC-machined stainless steel and aluminum components\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• low thermal expansion quartz primary and secondary mirrors \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• three built-in cooling fans in rear cell \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 3\" dual-speed Crayford focuser with 2\" and 1.25\" compression ring adapters \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• focuser attachment collar isolated from the primary mirror and baffle tube\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• dust covers and finder shoe\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e This newest version of the Astro-Tech AT10RCT makes 10\" coma-free true Ritchey-Chrétien imaging available to the DSLR and large format CCD astrophotographer at a price less than that of most large format CCD cameras by themselves.\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e Featuring premium low thermal expansion quartz mirrors, rather than aluminized Pyrex glass mirrors, this reasonably-priced 10\" Astro-Tech truss-tube R-C provides the coma-free photographic field that large format CCD and DSLR astrophotographers crave, but can't get from conventional reflectors and Schmidt-Cassegrains.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e Likewise, as a pure two-mirror system, the AT10RCT has a wide spectral response and is totally free from the spurious color that affects the imaging of all but the most costly apochromatic refractors, and it does it with a 12\" aperture that dwarfs the light gathering of every commercially-available apo refractor.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e If serious astrophotography is your goal, but the price of true Ritchey-Chrétien optics has been keeping you from the optical design most modern professional observatories use, your wait is over. The 10\" Astro-Tech AT10RCT truss-tube R-C can bring the world of professional DSLR\/CCD deep space imaging to your backyard observatory at a truly affordable price.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFeatures of this Astro-Tech AT10RCT Astrograph . . .\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptical design:\u003c\/strong\u003e true Ritchey-Chrétien Cassegrain-type two-mirror optics, with hyperbolic primary and secondary mirrors. The 233mm available back focus allows for the use of long CCD equipment trains.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptical specifications:\u003c\/strong\u003e 10\" aperture, 2000mm focal length, f\/8 focal ratio.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid primary mirror:\u003c\/strong\u003e Made of low thermal expansion quartz. Ground and polished under precision computer control and tested for accuracy multiple times during fabrication on Zygo interferometers. Unlike catadioptric designs (SCTs, Maksutovs, etc.) that move the primary mirror fore and aft in the optical tube to focus (which can lead to image shift and focal length changes as the mirror moves), the AT10RCT primary mirror is fixed to eliminate both image shift and focal length changes, as well as the frequent primary mirror collimation requirements of a Newtonian reflector. Primary mirror collimation is pre-set at the factory, but can be adjusted if needed using three traditional push\/pull locking adjustment screw sets.\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eHyperboloid secondary mirror: Made of low thermal expansion quartz, rather than Pyrex. Ground and polished under precision computer control and Zygo interferometer tested. Mounted in a CNC-machined four-vane spider and fully collimatable using simple standard Cassegrain reflector collimating techniques. The secondary mirror is precisely center-spotted to make collimation easier. Unlike complicated R-C designs that use motors to move the secondary mirror fore and aft to focus, which can lead to focal length changes, the AT10RCT secondary mirror is fixed and focusing is done externally by means of an optional external focuser, discussed below.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e In a review of Astro-Tech's original solid tube 8\" and 10\" R-Cs, Sky \u0026amp; Telescope said that the Astro-Tech R-C's fixed primary and secondary mirrors \"eliminate image shift, which has been the bane of Cassegrain scopes with moving-mirror focusing systems . . . It also keeps the effective focal length of the system constant, and the infinity focal point remains at a fixed point outside of the telescope, neither of which is the case with moving-mirror systems that change the separation between a Cassegrain's primary and secondary mirrors.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eCarbon fiber truss-tube design:\u003c\/strong\u003e Three CNC-machined aluminum support rings form the basic structure of the optical tube. Light-weight and rigid carbon fiber tubes connect the support rings in a Serrurier truss design, using CNC-machined stainless steel ball and socket hardware.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The Serrurier truss solves the problem of optical tube flexure by supporting the primary and secondary mirrors with two sets of opposing trusses mounted before and after the center support ring. The trusses are designed to have an equal amount of flexure, which allows the optics to stay on a common optical axis. When flexing, the \"top\" truss resists tension and the \"bottom\" truss resists compression. This has the effect of keeping the optical elements parallel to each other. The net result is that the optical elements stay in collimation regardless of the orientation of the telescope, including passing through the meridian during imaging.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The truss tubes are made of a light weight\/high strength woven carbon fiber-reinforced composite material with extremely low thermal expansion characteristics. This reduces the possibility of temperature-related focus changes that can occur with steel or aluminum optical tube scopes during extreme temperature swing.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The Astro-Tech AT10RCT is 24.4\" (620mm) long without focuser. The supplied focuser adds 5.25\" (133mm) with the drawtube retracted. The center and rear truss tube support rings are 15.74\" (400mm) in diameter, while the front support ring is 13.38\" (340mm) in diameter. The AT10RCT weighs 33.5 lbs (15.2 kg) without focuser. The supplied focuser adds 2.2 lbs (1 kg).\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003e3\" focuser:\u003c\/strong\u003e The AT10RCT is supplied with a basic light duty 3\" Crayford focuser to get you started imaging. While acceptable for casual imaging with a light imaging train (such as a light DSLR body by itself), upgrading to a high quality rack-and-pinion focuser is required for serious imaging with an optical tube of this quality. A heavy multi-component imaging train will require a rack-and-pinion focuser to support the extra weight without focus shift. Alternatively, you may already have a premium focuser being used on another scope that you would like to use for imaging.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The supplied light-duty Crayford focuser can be unthreaded from the focuser attachment collar, allowing you to use another focuser. One popular choice is the dual-speed 3\" diameter 1.5\" travel Feather Touch #3015 rack and pinion focuser, available from your Astro-Tech dealer.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The newly designed focuser attachment collar is bolted rigidly to the back plate of the AT10RCT, completely independent of the primary mirror and baffle tube. This allows it to be collimated separately from the primary and secondary mirrors if needed, using an optional #FCR1012 focuser collimating ring. The focuser attachment collar has a male 117m x 1mm pitch thread for attaching the focuser.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The Feather Touch #3015 normally comes with a 109mm threaded collar for connecting to a scope. Using the #3015 with the AT10RCT therefore requires an optional #M117x1 Feather Touch adapter. The #M117x1 adapter threads onto the focuser attachment port. The #3015 focuser (without its 109mm collar) then slips into the #M117x1 adapter and is held in place by three large brass Delrin-tipped retaining knobs. Only focusers with a maximum 1.5\" drawtube travel, such as the Feather Touch #3015, are recommended for use with the 12\" Astro-Tech AT10RCT Ritchey-Chrétien. For other focusers, such as a MoonLite, contact the focuser manufacturer for an adapter to fit the 117mm x 1mm port on the rear of the scope.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The image plane is located 9.2\" behind the rear cell (233mm from the top of the focuser attachment port). To fine-tune the back focus of the AT10RCT to the requirements of your camera and equipment train, three threaded extension rings (one 2\" in length and two 1\" in length) are provided to thread singly or in combination between the 117mm port on the AT10RCT rear cell and the focuser of your choice. These provide a flex-free solid metal extension that changes the distance between your chosen focuser and the rear cell. This lets you accommodate the varying back-focus requirements of DSLR-type camera imaging versus long equipment train CCD imaging. The 2\" x 117mm diameter threaded ring weighs 14.4 ounces; each 1\" ring weighs 7.2 oz.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eEquatorial mount recommendations:\u003c\/strong\u003e Because of the 33.5 pound (15.2 kg) weight of the AT10RCT (without focuser), plus the weight of your focuser, camera equipment, and any photoguide scope, installing the AT10RCT on a German equatorial mount with a 45 pound (minimum) to 100 pound or greater payload capacity is recommended. Such mounts include the 60 pound capacity CEM60, the 50 pound capacity Celestron CGX or 75 pound capacity CGX-L and the Losmandy 60 pound capacity G11 or 100 pound capacity HGM Titan. Other suitable mounts are also available from Software Bisque and Astro-Physics.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eCooling fans:\u003c\/strong\u003e To allow the AT10RCT to reach ambient temperatures more quickly for optimum imaging performance, there are three small low vibration\/high CFM primary mirror cooling fans built into the rear cell. The high speed DC fans are powered by a standard equipment battery pack that plugs into a jack on the rear cell. The battery pack uses eight user-supplied AA batteries. An optional external DC power supply, such as a rechargeable 12VDC battery pack can also be used to power the fans.\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTwo dovetail mounting rails: Two 9.8\" Losmandy-style \"D-plate\" dovetail rails are provided for installing the AT10RCT on an equatorial mount, as well as for mounting optional accessories (such as rings for a photoguide scope). One dovetail, positioned underneath the 15.75\" maximum diameter by 24.4\" long (without focuser) optical tube, connects the AT10RCT to your equatorial mount. The second rail, 180° away from the first, will then be on top of the tube for installing a photoguide scope or any other accessory that attaches to a scope by means of Losmandy-style \"D-plate\" dovetail adapters. The undersides of the dovetails have been hollowed out to lighten their weight without compromising their strength.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOther accessories:\u003c\/strong\u003e This new Version A of the AT10RCT includes slip-on dust covers for both the primary and secondary mirrors. Also included is a mounting shoe for a red dot-type finder, such as the Astro-Tech ATF. The mounting shoe can also accept the Astro-Tech ATF50QRB 50mm finderscope quick release bracket.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch2\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTech Details: \u003c\/span\u003e\u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eAperture\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e10\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e2000mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Ratio\u003c\/th\u003e\n\u003ctd class=\"data\"\u003ef\/8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e33.5 lbs.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eResolution\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e0.46 arc seconds\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTelescope Type\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eRitchey-Chrétien\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eVisual Limiting Magnitude\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e13.4\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBack Focus\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e233mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40217129680969,"sku":"AT10RCT","price":3195.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/20152_2.jpg?v=1662793486"},{"product_id":"1-25-99-reflectivity-dielectric-mirror-diagonal","title":"Astro-Tech 1.25\" 99% Reflectivity Dielectric Mirror Diagonal","description":"\u003cp\u003eThis 1.25\" Astro-Tech first-surface mirror star diagonal was named a \u003cem\u003eSky \u0026amp; Telescope Hot Product for 2007! \u003c\/em\u003eSky \u0026amp; Tel recognized that the Astro-Tech diagonal would be an outstanding value at even twice its low price. As it is, this Astro-Tech diagonal is unique among 1.25\" star diagonals for its exceptional price\/performance ratio. This is one premium-quality diagonal that doesn't happen to be priced like one - and it's still a hot product for many observers.\u003c\/p\u003e\n\u003cp\u003eThe Astro-Tech 1.25\" diagonal has state-of-the-art \u003cem\u003e46-layer \u003c\/em\u003edielectric mirror coatings for a full 99% reflectivity. This is markedly higher reflectivity than the 88% of a conventional aluminum diagonal or the 96-97% of an easily-tarnished silver diagonal. The result? Extremely faint deep space objects at your scope's performance limits become more visible, changing your viewing from \"I guess I see it\" to \"it's really there!\"\u003c\/p\u003e\n\u003cp\u003eThe mirror housing is precision-machined from solid aluminum, rather than simply flimsy Bakelite plastic or a sheet metal stamping, as you'll find with ordinary diagonals. A rigid machined metal backplate with stainless steel hardware holds the mirror in perfect optical alignment in the machined body. The interior of the body is anodized an antireflective matte black. The focuser-side barrel is also anodized antireflective matte black, and is internally antireflection threaded for even higher contrast. The barrel is threaded to accept standard 1.25\" filters.\u003c\/p\u003e\n\u003cp\u003eThe 1.25\" eyepiece holder uses a non-marring soft brass compression ring to clamp eyepieces in place, rather than a thumbscrew that can scratch an eyepiece barrel by tightening down on it directly.\u003c\/p\u003e\n\u003cp\u003eA shallow slanted groove cut into the outside of the focuser-side barrel engages with the scope's visual back or eyepiece holder thumbscrew to act as a safety stop. This keeps the diagonal from falling should the scope's thumbscrew loosen slightly from cold or use. Dust covers are provided for both sides of the diagonal.\u003c\/p\u003e\n\u003cp\u003eThis premium 1.25\" diagonal works with virtually any Schmidt-Cassegrain, Maksutov-Cassegrain, or refractor that uses a 1.25\" star diagonal,. It will provide a visible improvement on deep space objects over the scope's factory-supplied diagonal. The newly designed body of the Astro-Tech diagonal is more compact than previous diagonals. This essentially eliminates any possibility of the diagonal bumping into the drive base of a short fork arm catadioptric when the scope is pointed at the zenith. This \u003cem\u003eSky \u0026amp; Tel Hot Product \u003c\/em\u003egives you all the visual performance your scope is capable of delivering, at a price that's very affordable.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e5.5 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e2 years\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221659529289,"sku":"AT1D","price":79.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/10475_1.jpg?v=1662967572"},{"product_id":"astro-tech-2-99-reflectivity-dielectric-mirror-diagonal-for-refractors","title":"Astro-Tech 2\" 99% Reflectivity Dielectric Mirror Diagonal For Refractors","description":"\u003cp\u003eThis 2” dielectric mirror-type star diagonal is an outstanding value. At this low price, if there ever was a bargain in astronomy, this is it.\u003c\/p\u003e\n\u003cp\u003eThis 2” Astro-Tech first-surface mirror star diagonal has state-of-the-art 46-layer dielectric mirror coatings for a full 99% reflectivity, higher than the 88% of a conventional aluminum diagonal or the 96-97% of an easily-tarnished silver diagonal.\u003c\/p\u003e\n\u003cp\u003eThe durable ion-deposited dielectric coatings on the mirror’s finely-polished 10mm thick 1\/10th wave BK7 optical glass substrate also provide higher contrast and resolution during critical planetary, lunar, and binary star observations.\u003c\/p\u003e\n\u003cp\u003eThe supplied 1.25” eyepiece adapter uses a compression ring to hold eyepieces in place. The scope-side barrel of the 1.25” adapter has a subtle slanted groove to keep it from accidentally slipping out of the 2” diagonal. Dust covers are provided for the 1.25” adapter and the diagonal’s 2” barrel.\u003c\/p\u003e\n\u003cp\u003eThe interior of the diagonal body and the inside of the focuser-side barrel are treated with light absorbing materials. The focuser-side barrel is also internally anti-reflection threaded for even higher contrast. The barrel is threaded to accept standard 2” filters.\u003c\/p\u003e\n\u003cp\u003eA subtle slanted groove cut into the outside of the focuser-side 2” barrel engages with your telescope’s focuser thumbscrew to act as a safety stop. This keeps the diagonal from falling should the scope’s thumbscrew loosen slightly from cold or use.\u003c\/p\u003e\n\u003cp\u003eThis diagonal is a visible improvement over the conventional 2\" diagonal provided with many refractors capable of using 2” optics. It can also be used with a Schmidt-Cassegrain or Maksutov-Cassegrain telescope with a suitable adapter, such as the #7785C. It is an absolutely premium 2” 99% reflectivity dielectric self-centering star diagonal at a fraction the price of competitive models with equivalent performance and build quality. The same performance, for as little as half the price. If there ever was a bargain in astronomy, this is it.\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e17 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221659562057,"sku":"AT2D","price":129.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/img_1913.jpg?v=1662967573"},{"product_id":"2-99-reflectivity-dielectric-mirror-diagonal-for-scts","title":"Astro-Tech 2\" 99% Reflectivity Dielectric Mirror Diagonal for SCTs","description":"\u003cp\u003eThis 2\" \u003cem\u003edielectric \u003c\/em\u003emirror-type star diagonal is designed to give you first-class performance with a Schmidt-Cassegrain - at a money-saving and far from first-class price.\u003c\/p\u003e\n\u003cp\u003eThis 2\" Astro-Tech first-surface mirror star diagonal for catadioptric telescopes has state-of-the-art \u003cem\u003e46-layer \u003c\/em\u003edielectric mirror coatings for a full 99% reflectivity, higher than the 88% of a conventional aluminum diagonal or the 96-97% of an easily-tarnished silver diagonal. The durable ion-deposited dielectric coatings on the mirror's finely-polished 10mm thick 1\/10th wave BK7 optical glass substrate also provide higher contrast and resolution during critical planetary, lunar, and binary star observations. It has a physically short nosepiece and SCT rear cell attachment ring so it can clear the drive base on your telescope. You don't have to buy a special version of the diagonal or special adapters to be sure that it can swing through your 8\" scope's fork arms, as you do with some competitive diagonals. This Astro-Tech diagonal is, quite simply, unique among premium-quality 2\" SCT star diagonals for its exceptional value.\u003c\/p\u003e\n\u003cp\u003eThe SCT rear cell attachment ring will thread directly onto Celestron SCT rear cells and onto the rear cells of those Meade SCTs that do not have the electric microfocuser as standard equipment, These include older 2080 and 2120 scopes; all LX3, LX5, LX6, and Premier scopes; all current and past LX90s; and all earlier LX200 scopes that were supplied without microfocuser. The diagonal will thread onto a microfocuser-equipped scope if you install the SCT rear cell ring that came with the focuser into the microfocuser's 2\" drawtube. If you want a diagonal that will slip directly into the microfocuser's 2\" drawtube, order diagonal \u003ca href=\"astro-tech-2-inch-99-percent-reflectivity-dielectric-mirror-diagonal-refractors_p10504.aspx\"\u003e#AT2D 2\" 99% Reflectivity dielectric mirror diagonal for refractors\u003c\/a\u003e instead.\u003c\/p\u003e\n\u003cp\u003eThe mirror housing is precision-machined from solid aluminum, rather than simply flimsy plastic or a sheet metal stamping, as you'll find with ordinary diagonals. A rigid U-shaped die-cast metal backplate with stainless steel hardware holds the mirror in perfect optical alignment in the machined body. The solidity of the construction is mirrored in the diagonal's substantial 17 ounce weight.\u003c\/p\u003e\n\u003cp\u003eThe interior of the body is lined with light absorbing materials, in addition to being anodized an antireflective matte black. The short nosepiece that holds the rear cell attachment ring is internally antireflection threaded for high contrast. The attachment ring fits both Celestron and Meade rear cells. It is knurled for a sure grip so it can be easily loosened, allowing you to rotate the diagonal to the most comfortable observing position.\u003c\/p\u003e\n\u003cp\u003eRather than using a metal thumbscrew that contacts eyepiece barrels directly and can scratch them, the diagonal's 2\" eyepiece holder uses a non-marring soft brass compression ring to firmly hold 2\" eyepieces and the standard equipment 1.25\" eyepiece adapter. The knurled chrome thumbscrew that operates the compression ring is a full 1\/2\" in diameter, twice that of competitive diagonals. This provides a sure grip in cold weather when wearing gloves or mittens.\u003c\/p\u003e\n\u003cp\u003eThe 1.25\" eyepiece adapter also uses a compression ring to hold eyepieces in place. The 1.25\" adapter has a slanted groove cut into the outside of its focuser-side 2\" barrel. This engages with the diagonal's compression ring to act as a safety stop to keep the adapter from accidentally slipping out of the 2\" diagonal should the compression ring loosen during use. Dust covers are provided for the 1.25\" adapter and the diagonal's SCT attachment ring.\u003c\/p\u003e\n\u003cp\u003eThis diagonal is a visible improvement over the standard 1.25\" prism diagonal provided with virtually every Schmidt-Cassegrain or Maksutov-Cassegrain telescope. It is an absolutely top-rank 2\" 99% reflectivity dielectric star diagonal at only a fraction the price of competitive models with equivalent performance and build quality. The same premium performance, for as little as half the price. If there ever was a bargain in SCT astronomy, this is it.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e17 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221659594825,"sku":"AT2SD","price":149.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/10507_1.jpg?v=1662967575"},{"product_id":"illuminated-multiple-reticle-finder","title":"Astro-Tech Illuminated Multiple Reticle Finder","description":"\u003cp\u003eThe Astro-Tech #ATF multiple reticle finder is a single-power illuminated multiple reticle red-dot finder for astronomy and daylight terrestrial use. The lightweight and compact Astro-Tech finder features a precision ground reflex lens viewing window with minimal parallax; four different reticle patterns; seven brightness levels; and a two-part mounting base for installing the finder on a variety of telescopes.\u003c\/p\u003e\n\u003cp\u003eAny of four different reticle patterns can be selected by a lever at the rear of the finder. They include a single dot, such as that found in most traditional red dot finders; a plain crosshair; a circle with four short bars that extend out from the edges of the circle; and a dot within a circle.. The reticle patterns are projected on a multicoated optical glass viewing window that's roughly the proportions and shape (but not the actual size!) of a 16 x 9 HDTV screen. When the sky is viewed through the window, the red reticle appears to be superimposed on the sky or daytime landscape. You can choose the reticle pattern that best suits your viewing style and personal preferences. The actual projected reticles can be seen in the feature image below. A rubber cover is supplied to slip over the glass screen to protect its premium coatings when the scope is not in use.\u003c\/p\u003e\n\u003cp\u003eThe Astro-Tech finder is CNC-machined from solid aluminum for strength and durability, rather than being molded of fragile plastic, as are most red-dot finders. The finder is anodized a non-reflective matte black. The finder's matte black dovetail base is also CNC-machined from aluminum stock.\u003c\/p\u003e\n\u003cp\u003eThe supplied Vixen style mounting stalk lets you use the Astro-Tech multiple reticle finder with many Vixen\/Celestron\/Orion-style refractors or reflectors  that will let you mount the finder directly into an Astro-Tech\/Vixen\/Celestron\/Orion-style finder mounting shoe.\u003c\/p\u003e\n\u003cp\u003eThe bottom of the mounting stalk has a V-shaped base that is 30mm wide at its widest point. This will let it fit into the finder mounting bracket provided with most of the refractor and reflector telescopes from the above manufacturers. It lets you replace the inexpensive plastic single red dot finders and small refractor-type finders with the more flexible illuminated multiple reticle patterns of the Astro-Tech #ATF finder.\u003c\/p\u003e\n\u003cp\u003eThe top of the mounting stalk has narrow V-shaped ridges that the #ATF finder body clamps onto in order to lock the finder in place.\u003c\/p\u003e\n\u003cp\u003eClick-stop azimuth and altitude hex head adjustment bolts allow you to line up the finder with your main scope optics. The adjustments are very accurate, with each click stop equal to 1 arc minute of position change. The appropriate hex head wrenches are supplied for both clamping the finder to its base and making the altitude and azimuth adjustments.\u003c\/p\u003e\n\u003cp\u003eThere is a combined on-off switch and rotary brightness level control on top of the finder. The control provides seven click-stop brightness levels, allowing you to match the finder brightness to all lighting conditions and targets, from lining up on the Moon to the locating faint naked eye stars without having the finder brightness overpower the faintest stars.\u003c\/p\u003e\n\u003cp\u003eThe finder uses one user-replaceable 3 volt CR2032 lithium camera battery (supplied). Battery charge and battery life are not covered by the finder warranty. Replacement batteries are readily available at Wal-Mart, Radio Shack, camera stores, etc.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e8 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221661233225,"sku":"ATF","price":69.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/atfcrop.jpg?v=1756930249"},{"product_id":"astro-tech-8-f-8-ritchey-chretien-astrograph-carbon-fiber-tube","title":"Astro-Tech 8\" f\/8 Ritchey-Chrétien Astrograph, Carbon Fiber Tube","description":"\u003cp\u003eThe Astro-Tech AT8RC is the \u003cem\u003efirst \u003c\/em\u003eaffordable 8\" Ritchey-Chrétien with premium features available to the amateur astronomer who is into serious deep space imaging. \u003cem\u003eSky \u0026amp; Telescope \u003c\/em\u003e agrees, as they named the AT8RC a \u003cem\u003e\u003cspan style=\"font-family: verdana; font-size: 13px; color: #990000;\"\u003eSky \u0026amp; Telescope Hot Product for 2010\u003c\/span\u003e. \u003c\/em\u003eA review in the December 2009 \u003cem\u003eSky \u0026amp; Telescope\u003c\/em\u003e said \"it was how nicely this scope is matched to APS-C and 35mm formats that really wowed me.\"\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis Astro-Tech AT8RC Ritchey-Chrétien astrograph has:\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 8\" f\/8 true Ritchey-Chrétien hyperbolic mirror optical design\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• High strength\/low thermal expansion carbon fiber optical tube \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• ten contrast-enhancing main tube knife edge light baffles \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• dual-speed linear Crayford focuser\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 2\" and 1.25\" compression ring accessory holders \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• two dovetail rails - one Vixen-style and one Losmandy-style \"D-plate\"\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe AT8RC that Astro-Tech helped develop was the first sensibly-priced 8\" true Ritchey-Chrétien astrograph available from a U. S. company. Sensibly-priced? Yes - but with premium features like a carbon fiber body, quartz mirrors, two dovetail mounting rails, and more that led Sky \u0026amp; Telescope magazine to name it a Hot Product for 2010, along with its larger 10\" brother, the AT10RC.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eAs Sky \u0026amp; Telescope pointed out in their Hot Product citation, \"Ritchey-Chrétien reflectors are highly regarded among today's elite astrophotographers, and premium instruments often carry price tags starting at about $1,000 per inch of aperture. So it's the best kind of \"sticker shock\" to see the prices for Astro-Tech's 8- and 10-inch f\/8 Ritchey-Chrétiens, which pack features too numerous to list here. Our review of the 8-inch scope appears in December 2009, and our initial hands-on look at the 10-inch suggests that it will be equally exciting for deep sky astrophotographers.\" Excerpts from the December Sky \u0026amp; Telescope review are quoted below.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe Ritchey-Chrétien optical design is used in virtually every recent large mega-million dollar professional observatory telescope - including the Hubble Space Telescope. And more \"affordable\" true coma-free Ritchey-Chrétien optical systems made for schools and individuals by commercial R-C manufacturers typically come only in large apertures and often start at well over $1,000 per inch of aperture, as noted above by Sky \u0026amp; Telescope. Their size and cost put them out of the reach of most amateur astronomers. At least, true Ritchey-Chrétiens used to start at out-of-reach prices.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe Astro-Tech AT8RC astrograph (a telescope designed specifically for photographing comparatively wide areas of the sky) makes the coma-free imaging of true Ritchey-Chrétien imaging optics available to the DSLR and CCD astrophotographer at a price less than that of most CCD cameras. It is not designed for digiscoping through an eyepiece. \u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe December 2009 issue of Sky \u0026amp; Telescope said \"during the 1970s, there was an explosive growth of the hobby of deep-sky astrophotography that parallels the growing popularity of 8-inch f\/10 Schmidt-Cassegrain telescopes. These scopes delivered decent star images across a field about 3\/4° in diameter with enough resolution to record detail in small star clusters, nebulae, and galaxies. The AT8RC does that with even better star images, a larger field, and a slightly faster focal ratio. What's not to like?!\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eDesigned for exceptional imaging, the Astro-Tech AT8RC provides the wide coma-free photographic field that DSLR and CCD astrophotographers crave, but can't get from conventional reflectors and Schmidt-Cassegrains. Likewise, as a pure two-mirror system, the AT8RC is totally free from the spurious color that affects the imaging of all but the most costly apochromatic refractors, and it does it with an 8\" aperture that dwarfs the light gathering of most apo refractors.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe AT8RC photo of IC1396, the \"Elephant's Trunk Nebula,\" is from AT8RC owner John O'Neill. It was taken with an SBIG ST-10XME CCD camera and Astrodon filters. According to John, \"This scope performed exceptionally well, but the camera distance from the back of the scope may be a bit unsettling for some users.\" (See the section on the Crayford focuser, below, for an explanation.)\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\"The performance of the 8\" surprised me,\" John continued. \"I was able to get plenty of data using relatively short exposures of 400 sec x 4 through LRGB filters. Can't wait for the 12\" RC to be produced.\" \u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eIf serious astrophotography is your goal, but the price of most true Ritchey-Chrétien optics has been keeping you from the optical design most modern professional observatories and the Hubble Space Telescope use for their imaging, your wait is over. The Astro-Tech AT8RC astrograph can bring the world of professional DSLR\/CCD deep space imaging to your backyard observatory at a truly affordable price.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe December 2009 issue of Sky \u0026amp; Telescope said about the Astro-Tech AT8IN 8\" F\/4 imaging Newtonian optical tube, AT6RC, and AT8RC, \"of the three scopes, I liked this one (the AT8RC) the best. Its advanced features beyond those of the six-inch RC - carbon-fiber tube, quartz optics, and dual mounting rails (Losmandy and Vixen-style dovetails) - were part of the reason. But it was how nicely this scope is matched to APS-C and 35-mm formats that really wowed me.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eSky \u0026amp; Telescope concluded by saying, \"Astro-Tech has done a great job of balancing performance and price on all three of these imaging telescopes. By optimizing them for use with the cameras that many beginning and intermediate-level astrophotographers are using, the company has created affordable instruments that can produce stunning images. It's an exciting time to be entering the field of deep-sky astrophotography.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFeatures of this Astro-Tech AT8RC Astrograph . . .\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptical design:\u003c\/strong\u003e true Ritchey-Chrétien Cassegrain-type two-mirror optics, with hyperbolic primary and secondary mirrors.\u003c\/span\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e \u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptical specifications:\u003c\/strong\u003e 8\" aperture, 1625mm focal length, f\/8 focal ratio.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid primary mirror:\u003c\/strong\u003e Ground and polished under precision computer control to diffraction-limited or better surface accuracy. Unlike catadioptric designs (SCTs, Maksutovs, etc.) that move the primary mirror fore and aft in the optical tube to focus (which can lead to image shift as the mirror position changes) the AT8RC primary mirror is fixed to eliminate both a catadioptric's image shift and the primary mirror collimation requirements of a Newtonian reflector.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid secondary mirror:\u003c\/strong\u003e Ground and polished under precision computer control to diffraction-limited or better surface accuracy. Mounted in a four-vane spider and fully collimatable using simple standard Cassegrain reflector collimating techniques. Unlike complicated R-C designs that use motors to move the secondary mirror fore and aft to focus, the AT8RC secondary mirror is fixed and focusing is done externally.\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe December 2009 issue of Sky \u0026amp; Telescope said that the Astro-Tech R-Cs' fixed primary and secondary mirrors \"eliminate image shift, which has been the bane of Cassegrain scopes with moving-mirror focusing systems . . . It also keeps the effective focal length of the system constant, and the infinity focal point remains at a fixed point outside of the telescope, neither of which is the case with moving-mirror systems that change the separation between a Cassegrain's primary and secondary mirrors.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eCarbon fiber optical tube:\u003c\/strong\u003e Made of light weight\/high strength woven carbon fiber-reinforced composite material with extremely low thermal expansion characteristics to reduce the possibility of temperature-related focus changes that can occur with rolled steel tube systems during extreme temperature swings. Die-cast and machined aluminum front and rear cells. The 9\" o.d. x 18\" long carbon fiber tube is virtually indestructible. The use of a carbon fiber composite reduces the weight of the optical tube with no loss of strength or rigidity compared to a steel tube. Carbon fiber composites are so strong that the new $200,000,000 Boeing 787 Dreamliner passenger jet will use a wing and fuselage made almost entirely out of carbon fiber. Because of the use of a carbon fiber optical tube, the weight of this 8\" R-C is only a little more than two pounds heavier than the steel tube 6\" Astro-Tech R-C.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe December 2009 issue of Sky \u0026amp; Telescope said \"the carbon-fiber tube did a good job of holding focus over the modest temperature changes occurring during my summer evenings. More telling, perhaps, was the scope's tendency to remain accurately focused after several days of inactivity during which the temperature in my backyard observatory would cycle over a huge range.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eMultiple internal light baffles:\u003c\/strong\u003e Computer optimized primary and secondary baffling. Ten contrast-enhancing glare-stop baffles in the optical tube; multiple glare-stop microbaffles in the secondary mirror light shield; and five baffles in the primary mirror baffle tube provide truly dark sky backgrounds during imaging.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eDual-speed linear Crayford focuser:\u003c\/strong\u003e A new design 2\" Crayford focuser is threaded onto the 90mm x 1mm pitch rear cell of the AT8RC. The matte black interior of the new longer 50mm travel drawtube has anti-reflection threading for high contrast. The focuser can be rotated to any convenient angle for the sake of photographic composition by simply loosening the collar that secures the focuser to the scope body, rotating the focuser to the desired angle, and tightening the collar to lock the focuser in the new orientation.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe new bearing-less linear focuser has a polished stainless steel drive rail that runs the length of the drawtube, rather than having the stainless steel drive shaft simply press directly on (and wear) the aluminum drawtube as with conventional Crayford focusers. The drive rail rides in a self-lubricating track that extends most of the length of the focuser body. The drive rail and its attached drawtube are thereby supported over most of their length at all times, rather than by a conventional Crayford focuser's two sets of small contact area roller bearings. This system distributes the drive force evenly over the entire drawtube, without concentrating it on a few small contact points. The result is less potential drawtube flexure and no wear (much less uneven wear) on the drawtube.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe precision-made non-vignetting focuser has dual-speed focusing. There are two coarse focusing knobs. The right knob also has a smaller concentric knob with a 10:1 reduction gear microfine focusing ratio. This provides exceptionally precise image control during critical imaging. All focus knobs are ribbed, so they are easy to operate, even while wearing gloves or mittens in cold weather. Multiple internal baffles in the focuser drawtube assure high contrast.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eDespite the new more rigid focuser design, the weight of very heavy equipment trains (camera, plus filter wheel, plus temperature-compensated electric focuser, etc.) may cause the 50mm long focuser drawtube to tilt slightly when fully extended, affecting the focus. Three threaded extension rings (two 1\" in length and one 2\") are provided to install singly or in combination between the AT8RC rear cell and the focuser. These provide a flex-free solid metal extension that changes the distance between the focuser and the rear cell. This lets you accommodate the varying back-focus requirements of DSLR-type camera imaging versus long equipment train CCD imaging, while minimizing the need to extend the focuser drawtube. Additional optional 1\" and 2\" long threaded extension rings are available to fine-tune the back focus as needed, as well as optional Astro-Tech 2\" compression ring extension tubes that fit into the focuser drawtube.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe image plane is located 10\" behind the rear cell. With the standard dual-speed Crayford focuser installed on the scope, there is 159.71mm of back focus available from the top surface of the 2\" accessory holder to the image plane.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFor exceptionally long and heavy imaging equipment trains, the standard Crayford focuser can be user-replaced by an optional 1.5\" travel Feather Touch focuser from Starlight Instruments, #FT-1.5BC. This requires a 90mm x 1mm pitch rear cell thread to Feather Touch adapter, #M90X1. Optional MoonLite focusers from MoonLite Telescope Accessories can also be used.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFor even more impressive coma-free imaging with the AT8RC, consider adding the Astro-Tech AT2FF field flattener. While not specifically designed to work with Ritchey-Chrétien astrographs, images taken with the field flattener by Astro-Tech R-C owners have shown that the Astro-Tech 2\" field flattener works remarkably well with these advanced coma-free reflectors as well as with refractors. This modestly-priced imaging accessory essentially eliminates the residual field curvature inherent in all reflector telescope designs, so that the coma-free star images remain point-like all across the field. An optical analysis and ray tracing of the field flattener was done in ZEMAX and applied to the R-Cs by Roger Ceragioli, the noted optical designer who did the final optimization of the Astro-Tech Ritchey-Chrétien optics. Here is what he had to say about the #AT2FF, \"My conclusion, which seems supported by what users are saying, is that you don't need any other field flattener. This one performs well over a 40mm image circle in all three small RCs (6\", 8\", and 10\").\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eTwo compression ring accessory holders:\u003c\/strong\u003e The focuser drawtube ends in a 2\" accessory holder that uses a non-marring soft brass compression ring to hold 2\" imaging accessories in place. The compression ring won't scratch the barrel of your accessories as an ordinary thumbscrew can. Also supplied is a 1.25\" accessory holder that slips into the 2\" compression ring holder to let you use 1.25\" imaging accessories. Like the 2\" accessory holder on the drawtube, the 1.25\" adapter also uses a non-marring soft brass compression ring.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eTwo dovetail mounting rails:\u003c\/strong\u003e Two dovetail rails are provided for installing the AT8RC on an equatorial mount, as well as for mounting optional accessories (such as a photoguide scope) on top of the AT8RC. One is a Losmandy-style \"D-plate\" dovetail rail that runs the full length of the underside of the optical tube, for installing the AT8RC on a Losmandy-style equatorial mount. The second is a Vixen-style dovetail rail that runs the full length of the top of the tube. This can be used for installing a photoguide ring set, piggyback camera adapter, or any other accessory that attaches to a scope by means of Vixen-style dovetail adapters. If the AT8RC is rotated 180°, it will bring the Vixen-style rail to the bottom of the tube so it can be used to install the AT8RC on a Vixen-style equatorial mount. Competitors provide only one Vixen-style dovetail. Providing two dovetail rails on the Astro-Tech AT8RC does not limit your choice of mounts or accessory mounting options, as can happen with similar scopes provided with only one mounting rail.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eFinderscope dovetail:\u003c\/strong\u003e a Vixen-style finderscope bracket dovetail base is installed on the upper left side of the optical tube. It can easily be removed if not needed. It will accept Vixen-style finderscope brackets as well as red dot-type finders, such as the Astro-Tech #ATF.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOther accessories:\u003c\/strong\u003e A snap-in dust cap is standard.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch2\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTech Details: \u003c\/span\u003e\u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eAperture\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e8\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBinary and Star Cluster Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1625mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Ratio\u003c\/th\u003e\n\u003ctd class=\"data\"\u003ef\/8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eGalaxy and Nebula Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eLunar Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e16.4 lbs.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePlanetary Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eResolution\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e0.57 arc seconds\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTelescope Type\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eRitchey-Chrétien\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBack Focus\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e\n\u003cp\u003e10 (254mm) from rear cell, 6.25 (159mm) with standard focuser installed\u003c\/p\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003ch2\u003eSupplied Accessories: \u003c\/h2\u003e\n\u003cp\u003e\u003cmeta charset=\"UTF-8\"\u003e\u003cspan\u003e• 2\" and 1.25\" compression ring accessory holders \u003c\/span\u003e\u003cbr\u003e\u003cspan\u003e• two dovetail rails - one Vixen-style \u003c\/span\u003e\u003cem\u003eand \u003c\/em\u003e\u003cspan\u003eone Losmandy-style \"D-plate\"\u003c\/span\u003e\u003c\/p\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221663723593,"sku":"AT8RC","price":1395.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/15477.jpg?v=1662967711"},{"product_id":"astro-tech-vixen-style-mounting-bracket-for-astro-tech-multiple-reticle-finder","title":"Astro-Tech Vixen-Style Mounting Bracket for Astro-Tech Multiple Reticle Finder","description":"\u003cp\u003eThis Astro-Tech mounting stalk lets you use the Astro-Tech multiple reticle finder with many Vixen\/Celestron\/Orion-style refractors or reflectors . . .The Astro-Tech #ATFBV is a single-piece mounting stalk for the Astro-Tech #ATF multiple reticle finder that will let you mount the finder directly into a Vixen\/Celestron\/Orion-style finder mounting shoe.\u003c\/p\u003e\n\u003cp\u003eThe bottom of the mounting stalk has a V-shaped base that is 30mm wide at its widest point. This will let it fit into the finder mounting bracket provided with most of the refractor and reflector telescopes from the above manufacturers. It lets you replace the inexpensive plastic single red dot finders and small refractor-type finders with the more flexible illuminated multiple reticle patterns of the Astro-Tech #ATF finder.\u003c\/p\u003e\n\u003cp\u003eThe top of the mounting stalk has narrow V-shaped ridges that the #ATF finder body clamps onto in order to lock the finder in place.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e2 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221663789129,"sku":"ATFBV","price":10.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/15887.jpg?v=1662967714"},{"product_id":"astro-tech-5mm-1-25-paradigm-dual-ed","title":"Astro-Tech 5mm 1.25\" Paradigm Dual ED Eyepiece","description":"\u003cp\u003eThis Astro-Tech 5mm Paradigm Dual ED eyepiece is excellent for medium to medium high magnification viewing with short to medium focal length refractors and reflectors. It is also usable with long focal length refractors and catadioptric scopes under good or better seeing conditions.\u003c\/p\u003e\n\u003cp\u003eAverage seeing conditions will limit its usefulness with long focal length scopes due to the inherent high magnification of its 5mm focal length. Using it with a 2000mm 8\" f\/10 catadioptric, for example, will result in 400x (50x per inch of aperture) and a 0.5mm exit pupil (about 1\/50th of an inch across). Both of these are right at the rule of thumb limits for maximum magnification per inch of aperture and minimum exit pupil size for usable observing under good to very good seeing conditions for a reasonably experienced observer.\u003c\/p\u003e\n\u003cp\u003eThe six lens\/four group design and two ED (Extra-low Dispersion) glass elements of the 5mm Astro-Tech Paradigm provides all of the optical virtues described at the top of this catalog page - high contrast, a sharp and flat field from edge to edge, excellent color fidelity, and exceptionally low astigmatism and barrel distortion. It has a usable eye relief of 13mm, excellent for such a short focal length eyepiece. Combined with the twist-up eyecup design, the long eye relief makes it a good choice for eyeglass wearers.\u003c\/p\u003e\n\u003cp\u003eThis new Astro-Tech 5mm Paradigm Dual ED eyepiece will make you rethink your expectations about how much sheer short focal length eyepiece excellence you can get for such a reasonable price.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eBarrel Size\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eEye Relief\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e13mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eField of view\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e60\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eNumber of optical elements\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e7.2 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221664837705,"sku":"ATPARA05","price":69.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/5mm1.25_Paradigm_1-10879.jpg?v=1738261268"},{"product_id":"astro-tech-8mm-1-25-paradigm-dual-ed","title":"Astro-Tech 8mm 1.25\" Paradigm Dual ED Eyepiece","description":"\u003cp\u003eThis Astro-Tech 8mm Paradigm Dual ED eyepiece is a logical choice for high quality\/high magnification observing with long focal length refractors, reflectors, or catadioptric scopes under good to somewhat better than average seeing conditions. Below average seeing conditions may limit its performance.\u003c\/p\u003e\n\u003cp\u003eIf so-so seeing is the norm where you observe, its 8mm focal length may represent the shortest focal length practical with a long focal length telescope for observing lunar and planetary detail, resolving globular clusters, picking up small planetary nebulas against a stellar background, etc.\u003c\/p\u003e\n\u003cp\u003eContrast is very good for planetary and lunar use, rivaling that of orthoscopics and Brandons, but with a substantially wider field of view and excellent eye relief. Its sharpness and lack of astigmatism across the field makes smaller globular clusters vivid and nearly three-dimensional.\u003c\/p\u003e\n\u003cp\u003eThe six lens\/four group design and two ED (Extra-low Dispersion) glass elements of the 8mm Astro-Tech Paradigm provides all of the optical virtues described at the top of this catalog page - high contrast, a sharp and flat field from edge to edge, excellent color fidelity, and exceptionally low astigmatism and barrel distortion. It has a usable eye relief of 13mm, excellent for an eyepiece in this focal length range. Combined with the twist-up eyecup design, the long eye relief makes it a good choice for eyeglass wearers.\u003c\/p\u003e\n\u003cp\u003eThis new Astro-Tech 8mm Paradigm Dual ED eyepiece will make you rethink your expectations about just how good an 8mm eyepiece you can get for such a reasonable price - and make you wonder why other manufacturers can't do as well.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eBarrel Size\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eEye Relief\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e13mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eField of view\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e60\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e8mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eNumber of optical elements\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6.4 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221664870473,"sku":"ATPARA08","price":69.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/8mm1.25_Paradigm_1-10885.jpg?v=1738261325"},{"product_id":"astro-tech-12mm-1-25-paradigm-dual-ed","title":"Astro-Tech 12mm 1.25\" Paradigm Dual ED Eyepiece","description":"\u003cp\u003eThis Astro-Tech 12mm Paradigm Dual ED medium power eyepiece has outstanding performance at a price that will make you wonder why other good quality eyepieces cost so much more . . .This medium focal length Astro-Tech 12mm Paradigm Dual ED eyepiece is usable with any telescope type, under virtually any seeing conditions - from fair to superb. (Rain, snow, or fog might limit its usefulness, however.)\u003c\/p\u003e\n\u003cp\u003eWith a short focal length refractor it is a low power eyepiece. With the 430mm focal length Astro-Tech AT72ED, for example, its six lens\/four group multicoated dual ED (Extra-low Dispersion) glass optics provide 36x and a field over three times as wide as the full Moon. This is well suited for observing globular clusters such as M13 and M22. Both fit nicely into its 1.67° field with the AT72ED, with a framework of black sky around the clusters to set them off. Its sharpness and lack of astigmatism across the field make globular clusters sharp, vivid, and nearly three-dimensional.\u003c\/p\u003e\n\u003cp\u003eIt is also quite remarkable for medium high magnification observing with long focal length refractors, reflectors, or catadioptric scopes. On an 8\" f\/10 catadioptric, for example, it yields 167x. This is an excellent magnification for planetary and close-up lunar observing, particularly when the high contrast of the eyepiece (rivaling that of orthoscopics and Brandons) is combined with its excellent color fidelity. Its overall performance makes it a much better choice as a second eyepiece than merely doubling the power of most scopes' so-so standard 25-26mm eyepiece with a Barlow.\u003c\/p\u003e\n\u003cp\u003eThe six lens\/four group design and two ED (Extra-low Dispersion) glass elements of the 12mm Astro-Tech Paradigm provides all of the optical virtues described at the top of this catalog page - high contrast, a sharp and flat field from edge to edge, excellent color fidelity, and exceptionally low astigmatism and barrel distortion. It has a usable eye relief of 13mm, very good for an eyepiece in this focal length range. Combined with the twist-up eyecup design, the long eye relief makes it a good choice for eyeglass wearers.\u003c\/p\u003e\n\u003cp\u003eThis new Astro-Tech 12mm Paradigm Dual ED eyepiece will make you drastically revise your expectations upwards when it comes to how much optical excellence you can get for such a reasonable price.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eBarrel Size\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eEye Relief\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e13mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eField of view\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e60\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e12mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eNumber of optical elements\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6.4 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221664903241,"sku":"ATPARA12","price":69.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/12mm1.25_Paradigm_1-10886.jpg?v=1738261487"},{"product_id":"astro-tech-15mm-1-25-paradigm-dual-ed","title":"Astro-Tech 15mm 1.25\" Paradigm Dual ED Eyepiece","description":"\u003cp\u003eThis Astro-Tech 15mm Paradigm Dual ED eyepiece gives you the outstanding medium power performance of a high-priced eyepiece at a price that will make you wonder why other eyepieces \u003cem\u003eare \u003c\/em\u003eso high-priced . . .This Astro-Tech 15mm Paradigm Dual ED is an excellent medium power eyepiece for lunar observing, encompassing globular clusters, picking up detail in emission and reflection nebulas, etc. This 15mm focal length is a good choice for filling in the gap between the 25\/26mm eyepiece that comes standard with most telescopes and a high power planetary\/binary star splitting eyepiece. It is usable with any telescope type, under virtually any seeing conditions - from fair to superb. (Rain, snow, or fog might limit its usefulness, however.)\u003c\/p\u003e\n\u003cp\u003eWith a short focal length refractor it is a medium to low power eyepiece well suited to scanning the teeming star clouds of Sagittarius. With the 400mm focal length Astro-Tech AT66ED, for example (a compact 66mm aperture telescope \u003cem\u003eAstronomy \u003c\/em\u003emagazine said \"everyone should own\"), its six lens\/four group two ED lens optics provide 27x and a field well over four times as wide as the full Moon. This is well suited for observing open clusters such as the Pleiades, and nebulas such as the Lagoon. Both fit nicely into its 2.22° field with the AT66ED, with a framework of black velvet sky around them to set them off.\u003c\/p\u003e\n\u003cp\u003eIt is also quite remarkable for medium high magnification observing with long focal length refractors, reflectors, or catadioptric scopes. On an 8\" f\/10 catadioptric, for example, it yields 133x. This is an excellent magnification for planetary and close-up lunar observing, particularly when the high contrast of the eyepiece (rivaling that of orthoscopics and Brandons) is combined with its excellent color fidelity. Its overall performance makes it a much better choice as a second eyepiece than merely doubling the power of most scopes' so-so standard 25-26mm eyepiece with a Barlow.\u003c\/p\u003e\n\u003cp\u003eThe six lens\/four group design and two ED (Extra-low Dispersion) glass elements of the 15mm Astro-Tech Paradigm provides all of the optical virtues described at the top of this catalog page - high contrast, a sharp and flat field from edge to edge, excellent color fidelity, and exceptionally low astigmatism and barrel distortion. It has a long usable eye relief of 15mm. Combined with the twist-up eyecup design, the long eye relief makes it a good choice for eyeglass wearers.\u003c\/p\u003e\n\u003cp\u003eThis new Astro-Tech 15mm Paradigm Dual ED eyepiece will change your mind about how much truly good optical performance should cost. But be warned. The view through the 15mm Paradigm may tempt you to upgrade all your eyepieces to Paradigms.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eBarrel Size\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eEye Relief\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e15mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eField of view\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e60\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e15mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eNumber of optical elements\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6.4 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221665001545,"sku":"ATPARA15","price":69.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/15mm1.25_Paradigm_1-10888.jpg?v=1738261509"},{"product_id":"astro-tech-18mm-1-25-paradigm-dual-ed","title":"Astro-Tech 18mm 1.25\" Paradigm Dual ED Eyepiece","description":"\u003cp\u003eThis Astro-Tech 18mm Paradigm Dual ED is an excellent medium to medium low power eyepiece for lunar observing, encompassing globular clusters, picking up detail in emission and reflection nebulas, etc. This 18mm focal length is a good choice for filling in the gap between the 25\/26mm eyepiece that comes standard with most telescopes and a high power planetary\/binary star splitting eyepiece. It is usable with any telescope type, under virtually any seeing conditions - from fair to superb. (Rain, snow, or fog might limit its usefulness, however.)\u003c\/p\u003e\n\u003cp\u003eWith a short focal length refractor it is a medium to low power eyepiece well suited to scanning the crowded star clouds of Sagittarius. For example, with the 430mm focal length f\/6 Astro-Tech AT72ED it provides 24x, a field five times as wide as the full Moon, and a 3mm exit pupil that is excellent for rich field observing and revealing large nebulas.\u003c\/p\u003e\n\u003cp\u003eIt is also a good choice for medium power observing with long focal length refractors, reflectors, or catadioptric scopes. On an 8\" f\/10 catadioptric, for example, it yields 111x, with a 0.54° field. This is a very useful magnification for observing compact planetary nebulas and globular clusters, as well as lunar observing. Its high contrast makes observing small features along the lunar terminator a nightly delight as the terminator creeps across the face of the Moon.\u003c\/p\u003e\n\u003cp\u003eThe six lens\/four group design and two ED (Extra-low Dispersion) glass elements of the 18mm Astro-Tech Paradigm provides all of the optical virtues described at the top of this catalog page - high contrast, a sharp and flat field from edge to edge, excellent color fidelity, and exceptionally low astigmatism and barrel distortion. It has a usable eye relief of 13mm. Combined with the twist-up eyecup design, the good eye relief makes it a sensible choice for eyeglass wearers.\u003c\/p\u003e\n\u003cp\u003eThis new Astro-Tech 18mm Paradigm Dual ED eyepiece will make your nightly views of the heavens sharper, clearer, and more entrancing than ever before. The Paradigm will change your mind about how much truly high-end optical performance not much money can buy.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eBarrel Size\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eEye Relief\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e13mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eField of view\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e60\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e18mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eNumber of optical elements\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e5.6 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221665198153,"sku":"ATPARA18","price":69.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/18mm1.25_Paradigm_1-10890.jpg?v=1738261534"},{"product_id":"astro-tech-25mm-1-25-paradigm-dual-ed","title":"Astro-Tech 25mm 1.25\" Paradigm Dual ED Eyepiece","description":"\u003cp\u003eThis Astro-Tech 25mm Paradigm Dual ED is an excellent medium to low power eyepiece for encompassing open clusters, picking up detail in emission and reflection nebulas while still viewing them in their entirety, etc. This high quality 25mm focal length optical gem will visibly upgrade the performance of the usually only so-so 25\/26mm eyepiece that typically comes standard with most telescopes. It is also a good choice to complement the 40mm eyepiece provided with some go-to Schmidt-Cassegrains. The 25mm Astro-Tech Paradigm is usable with any telescope type, under virtually any seeing conditions - from fair to superb. (Rain, snow, or fog might limit its usefulness, however.)\u003c\/p\u003e\n\u003cp\u003eWith a short focal length refractor it is a low power eyepiece well suited to scanning the crowded star clouds of Sagittarius, observing galaxy clusters, framing the more compact emission nebulas with the black of space, observing the nebulosity around the Pleiades, etc. With the 430mm focal length f\/6 Astro-Tech AT72ED, its six lens\/four group two ED lens optics provide a magnification of 17x, a field nearly seven times as wide as the full Moon, and a 4.16mm exit pupil that is ideal for rich field observing.\u003c\/p\u003e\n\u003cp\u003eThe 25mm Astro-Tech Paradigm is also a good choice for medium power observing with long focal length refractors, reflectors, and catadioptric scopes. On an 8\" f\/10 catadioptric, for example, it yields 80x, with a 0.75° field that is half again as wide as the full Moon. This is a very useful magnification for observing compact planetary nebulas and globular clusters, as well as lunar observing. Its high contrast makes observing small features along the lunar terminator a nightly delight as the terminator creeps across the face of the Moon.\u003c\/p\u003e\n\u003cp\u003eThe six lens\/four group design and two ED (Extra-low Dispersion) glass elements of the 25mm Astro-Tech Paradigm provides all of the optical virtues described at the top of this catalog page - high contrast, a sharp and flat field from edge to edge, excellent color fidelity, and exceptionally low astigmatism and barrel distortion. It has a usable eye relief of 15mm. Combined with the twist-up eyecup design, the good eye relief makes it a sensible choice for eyeglass wearers.\u003c\/p\u003e\n\u003cp\u003eThis Astro-Tech 25mm Paradigm Dual ED eyepiece will upgrade your scope's starter eyepiece, bringing new life to your nightly views of the heavens. The 25mm Paradigm will change your mind about just how good low power viewing with a telescope can be, with truly high-end optical performance at a not very high-end price.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eBarrel Size\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eEye Relief\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e15mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eField of view\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e60\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e25mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eNumber of optical elements\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6.4 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221665263689,"sku":"ATPARA25","price":69.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/25mm1.25_Paradigm_1-10891.jpg?v=1738261553"},{"product_id":"astro-tech-1-25-nd9-13-transmission-neutral-density-grey-moon-filter","title":"Astro-Tech 1.25\" #ND9 13% Transmission Neutral Density Grey Moon Filter","description":"\u003cp\u003eThis economical Astro-Tech ND9 neutral gray filter reduces the brightness and glare that can mask low contrast details during lunar and planetary visual observing. It does so without affecting the natural colors of the solar system object being observed. It can also be very effective when used with some webcam and DSI-type cameras to reduce the brightness of the Moon to keep from saturating the imaging detector during lunar photography.\u003c\/p\u003e\n\u003cp\u003eThe filter is mounted in a standard 1.25\" threaded cell. It will thread into the barrel of any 1.25\" eyepiece or into the 1.25\" nosepiece of webcams, DSI-type cameras, or CCD cameras or filter wheels that accepts 1.25\" filters. The filter comes in a hard plastic protective case.\u003c\/p\u003e\n\u003cp\u003eDue to its low 13% light transmission, it works best with scopes 6\"-8\" and larger. Its price is particularly cost-effective when compared with higher-priced competitive filters of equivalent performance.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eColor\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e96ND9 - Neutral Density 0.9\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e0.5 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221665329225,"sku":"ATND9","price":12.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/16961.jpg?v=1662967756"},{"product_id":"astro-tech-2-x-35mm-extension-tube","title":"Astro-Tech 2\" x 35mm Extension Tube","description":"\u003cp\u003eThis Astro-Tech 2\" x 35mm extension tube is used to make up for the loss of light path when a 2\" star diagonal is removed from many refractor focusers and replaced by a camera and camera adapter for imaging. It can also be used with Astro-Tech Ritchey-Chrétien reflectors to bring webcams and DSLRs to the correct focus . . .This Astro-Tech 35mm long x 2\" diameter extension tube can be used to make up for the loss of light path when a 2\" star diagonal is removed from many refractor telescope focusers and replaced by a camera and camera adapter for imaging. In some cases, it is also useful to replace the light path lost when a full-sized 2\" diagonal is replaced in the scope by a shorter light path 1.25\" diagonal.\u003c\/p\u003e\n\u003cp\u003eThis Astro-Tech extension tube can also be used with Astro-Tech Ritchey-Chrétien reflectors. With these Astro-Tech scopes, the scope's focuser is used by itself or (more typically) in combination with one or both of the thread-on extension rings supplied with the scope to place the camera at the telescope's focal plane.\u003c\/p\u003e\n\u003cp\u003eIn some cases, however, there may not be quite enough focuser extension for webcam use when using both thread-on extension rings with an Astro-Tech R-C, or the two extensions might be too long to bring a DSLR to focus while one extension might not be long enough. This 2\" compression ring extension tube can be slipped into the 2\" accessory holder of the Astro-Tech R-C's focuser to add the extra focuser length needed. Optional Astro-Tech 50mm and 80mm extension tubes are also available. A little experimentation will be called for to determine what combination of focuser and extension tube(s) will be needed for your particular combination(s) of visual and\/or photographic components.\u003c\/p\u003e\n\u003cp\u003eOne end of this Astro-Tech 2\" diameter x 35mm long extension tube fits into 2\" focuser drawtubes. This end is threaded to accept 48mm filters. A shallow safety groove is machined into the barrel of the extension tube. This groove engages the thumbscrew or compression ring of your focuser to prevent the extension tube and your camera from falling should the focuser thumbscrew loosen accidentally during use. The barrel extends 35mm into the focuser drawtube to provide a secure tilt-free installation when the focuser thumbscrew is firmly tightened.\u003c\/p\u003e\n\u003cp\u003eThe opposite end of the extension tube has a 2\" diameter accessory holder with a non-marring brass compression ring. A single thumbscrew tightens the compression ring on your 2\" accessories to hold them firmly in place. This accessory holder adds 35mm of extension to the light path when the extension tube is seated firmly into your focuser. The overall length of the extension tube is 70mm, 35mm extending into your focuser with 35mm of external light path extension. The extension tube is machined of aluminum, anodized black. The interior has anti-reflection threading.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e4 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221665361993,"sku":"AT35EXT","price":29.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/17010.jpg?v=1662967758"},{"product_id":"astro-tech-2-x-50mm-extension-tube","title":"Astro-Tech 2\" x 50mm Extension Tube","description":"This Astro-Tech 2\" x 50mm extension tube is used to make up for the loss of light path when a 2\" star diagonal is removed from many refractor focusers and replaced by a camera and camera adapter for imaging. It can also be used with Astro-Tech Ritchey-Chrétien reflectors to bring webcams and DSLRs to the correct focus . . .This Astro-Tech 50mm long x 2\" diameter extension tube can be used to make up for the loss of light path when a 2\" star diagonal is removed from many refractor telescope focusers and replaced by a camera and camera adapter for imaging.\n\u003cp\u003eThis Astro-Tech extension tube can also be used with Astro-Tech Ritchey-Chrétien reflectors. With these Astro-Tech scopes, the scope's focuser is used by itself or (more typically) in combination with one or both of the thread-on extension rings supplied with the scope to place the camera at the telescope's focal plane.\u003c\/p\u003e\n\u003cp\u003eIn some cases, however, there may not be quite enough focuser extension for webcam use when using both thread-on extension rings with an Astro-Tech R-C, or the two extensions might be too long to bring a DSLR to focus while one extension might not be long enough. This 2\" compression ring extension tube can be slipped into the 2\" accessory holder of the Astro-Tech R-C's focuser to add 50mm of extra focuser length. Optional Astro-Tech 35mm and 80mm extension tubes are also available. A little experimentation will be called for to determine what combination of focuser and extension tube(s) will be needed for your particular combination(s) of visual and\/or photographic components.\u003c\/p\u003e\n\u003cp\u003eOne end of this Astro-Tech 2\" diameter x 50mm long extension tube fits into 2\" focuser drawtubes. This end is threaded to accept 48mm filters. A shallow safety groove is machined into the barrel of the extension tube. This groove engages the thumbscrew or compression ring of your focuser to prevent the extension tube and your camera from falling should the focuser thumbscrew loosen accidentally during use. The barrel extends 35mm into the focuser drawtube to provide a secure tilt-free installation when the focuser thumbscrew is firmly tightened.\u003c\/p\u003e\n\u003cp\u003eThe opposite end of the extension tube has a 2\" diameter accessory holder with a non-marring brass compression ring. A single thumbscrew tightens the compression ring on your 2\" accessories to hold them firmly in place. This accessory holder adds 50mm of extension to the light path when the extension tube is seated firmly into your focuser. The overall length of the extension tube is 85mm, 35mm extending into your focuser with 50mm of external light path extension. The extension tube is machined of aluminum, anodized black. The interior has anti-reflection threading.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e5.5 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221665427529,"sku":"AT50EXT","price":29.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/17011.jpg?v=1662967759"},{"product_id":"astro-tech-2-field-flattener-for-imaging-with-astro-tech-and-tmb-refractors","title":"Astro-Tech 2\" Field Flattener for Imaging with Astro-Tech and TMB Refractors","description":"\u003cp\u003eNew for August 2021, thread on adatper tops to choose between 42mm T-threads and 48mm T-threads.\u003c\/p\u003e\n\u003cp\u003eNamed a \u003cem\u003e\u003cspan style=\"font-family: verdana; color: #990000;\"\u003eSky \u0026amp; Telescope Hot Product of the Year for 2010\u003c\/span\u003e, \u003c\/em\u003ethe Astro-Tech photographic field flattener reduces the normal field curvature inherent in all refractors to provide you with images that are sharply focused out to the very corners of your DSLR or large format CCD imager frame. Stars on your images look sharp and point-like all the way across the field. You don't have to worry about photos that are sharp in the center but out of focus at the edges. The field flattener also works surprisingly well with the 6\", 8\", and 10\" Astro-Tech Ritchey-Chrétien astrographic reflectors.\u003c\/p\u003e\n\u003cp\u003eAs \u003cem\u003eSky \u0026amp; Telescope \u003c\/em\u003epointed out in their Hot Product citation, \"With only a few noteworthy (and expensive) exceptions, refractors need optional field flatteners in order to deliver acceptable star images across the field of today's DSLR cameras. Custom-designed flatteners usually cost hundreds of dollars, but the Astro-Tech 2\" Field Flattener is only $139. Furthermore, it's designed for any refractor with a focal ratio between f\/6 and f\/8. And there are reports that helps flatten the field of Astro-Tech Ritchey-Chrétien astrographs. The flattener was reviewed in the September 2009 issue of \u003cem\u003eSky \u0026amp; Telescope, \u003c\/em\u003epage 38.\"\u003c\/p\u003e\n\u003cp\u003eDesigned to work purely as a field flattener for imaging, and not simultaneously as a focal reducer or telecompressor, the 2\" Astro-Tech field flattener does not change the focal length or focal ratio of your telescope. It is not designed for visual use, having photographic T-threads only and no provision for using a star diagonal or eyepieces.\u003c\/p\u003e\n\u003cp\u003eA separate review in \u003cem\u003eSky \u0026amp; Telescope \u003c\/em\u003emagazine of the Astro-Tech field flattener and the Astro-Tech AT106 refractor said the field flattener was \"extremely easy to use with any SLR camera. You simply screw on the appropriate T-ring, connect your camera, and slip the flattener into the AT106's 2-inch focuser. Daylight shots made two things immediately apparent - the field flattener does not change the telescope's focal length (it's a true zero-power flattener), and it sharpens images at the edge of the field . . . At night, star images in the corners of my Nikon D300's APS-format frame, while vastly better than those recorded without the flattener, still showed a slight elongation . . . By focusing at a point slightly off center, thus balancing the imaging performance between the center and edge of the field, I could fill the frame with nice, round star images. For photographers shooting day or night, the flattener is well worth its current $150 price.\"\u003c\/p\u003e\n\u003cp\u003e\u003cimg alt=\"\" style=\"float: right; margin-left: 15px; margin-right: 15px; border-width: 1px; border-style: solid;\"\u003e\u003c\/p\u003e\n\u003cp\u003eWhile not specifically designed to work with Ritchey-Chrétien astrographs, images taken with the field flattener by Astro-Tech R-C owners have shown that the Astro-Tech 2\" field flattener works remarkably well with these advanced coma-free reflectors as well as with refractors. Comments like \"Works great on my AT8RC. Won't image without it,\" and \"Works well with my AT6RC,\" show up regularly in on-line imaging forums. An optical analysis and ray tracing of the field flattener was done in ZEMAX and applied to the R-Cs by Roger Ceragioli, the noted optical designer who did the final optimization of the design of the Astro-Tech Ritchey-Chrétiens. Here is what he had to say about the #AT2FF, \"My conclusion, which seems supported by what users are saying, is that you don't need any other field flattener. This one performs well over a 40mm image circle in all three small RCs (6\", 8\", and 10\").\"\u003c\/p\u003e\n\u003cp\u003eThe 2\" barrel of the fully multicoated dual-element Astro-Tech field flattener inserts directly into your scope's 2\" focuser drawtube. A groove machined into the field flattener barrel engages the thumbscrew or compression ring of your focuser to act as a safety stop. This prevents the field flattener and camera from falling to the ground should the thumbscrew or compression ring accidentally loosen during use.\u003c\/p\u003e\n\u003cp\u003eThe AT2FF now comes with threaded adapter tops for 42mm x 0.75mm pitch , or 48mm x 0.75mm pitch, T-2 photographic T-threads on the observer\/camera side of the black anodized field flattener accept a standard T-ring for connecting a 35mm or DSLR camera to the field flattener. They also allow direct connection to many CCD camera\/color filter wheel combinations.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSpacing from field flattener to film plane: \u003c\/strong\u003eOptimal spacing from the shoulder of the field flattener (where a T-ring threads on) to a camera's imaging sensor or film plane is 57mm +\/- 4mm. The following DSLR camera body\/T-ring combinations typically all fall within this optimum spacing range and generally should require no additional spacers.\u003c\/p\u003e\n\u003cp\u003eA Canon EOS DSLR\/T-ring combination typically has a T-ring front flange to camera sensor spacing of approximately 55.5mm, although this number is dependent on the thickness of the T-ring you use and cannot be guaranteed. (Without T-ring, the distance from the front flange of the camera body to the sensor is approximately 44mm by itself.)\u003c\/p\u003e\n\u003cp\u003eA Minolta\/Sony DSLR and T-ring combo typically has an approximately 54mm T-ring front flange to sensor spacing. The exact number is again dependent on the thickness of your T-ring. (The camera front flange to sensor distance by itself is approximately 43.5mm.)\u003c\/p\u003e\n\u003cp\u003eA Nikon DSLR and T-ring combo typically has a total spacing of approximately 56mm. This number is again dependent on the T-ring thickness. (The camera front flange to sensor spacing is typically 46.5mm by itself.)\u003c\/p\u003e\n\u003cp\u003eWith CCD and DSI-type cameras, some experimentation with spacers will be necessary to achieve optimum performance, as these typically have much shorter camera front plate to sensor spacing than DSLR cameras.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e8 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221666836553,"sku":"AT2FF","price":149.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/img_2026.jpg?v=1662967803"},{"product_id":"astro-tech-8-f-4-imaging-newtonian-optical-tube","title":"Astro-Tech 8\" f\/4 Imaging Newtonian Optical Tube","description":"\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eA review of three Astro-Tech astrographs (the AT6RC and AT8RC Ritchey-Chrétiens, as well as this AT8IN Imaging Newtonian) in the December 2009 issue of Sky \u0026amp; Telescope said \"While all three of the Astro-Tech scopes represent excellent value, the AT8IN, with its 8-inch aperture and $499 price tag, wins the biggest-bang-for-the-buck award . . . there's a quality to this scope that seems contradictory to its relatively low cost.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis Astro-Tech Imaging Newtonian optical tube has:\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• very fast f\/4 focal ratio 8\" Newtonian reflector optics\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• contrast-enhancing extended tube length with 15 internal baffles \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• built-in cooling fan for faster primary mirror cooldown \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 2\" dual-speed Crayford focuser with 2\" and 1.25\" compression ring accessory adapters \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 8 x 50mm finderscope in a quick-release bracket \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• dual split hinged mounting rings\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis 8\" Astro-Tech AT8IN optical tube is a very fast focal ratio f\/4 reflector that has been optimized for wide field deep space imaging. It can be used with 35mm cameras, DSLRs, web-cams, DSI-type cameras, and large format CCD cameras alike.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eAstronomy named the Astro-Tech AT8IN a Star Product for 2010, saying \"Astronomy Technologies has optimized the AT8IN for astroimaging, but the scope is just as adept for backyard viewing . . . a versatile instrument that will take you into the depths of the universe in style.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The light weight standard equipment mounting rings of the Astro-Tech Imaging Newtonian allow you to use it on a wide variety of dovetail plates and German equatorial mounts - from the most basic to the most elaborate high payload go-to system.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eIn addition to deep space imaging, the Astro-Tech AT8IN is also usable for solar system imaging as well as deep space and solar system visual observing. Solar system visual contrast will be somewhat reduced compared to a longer focal ratio reflector because of the AT8IN's larger secondary mirror that has been optimized for full-field photographic illumination. However, the visual performance will still be much more than acceptable, and the 800mm focal length of this Astro-Tech makes it quite possible to achieve the high powers needed for detailed lunar and planetary observing. Simply add optional 1.25\" or 2\" eyepieces, and perhaps an optional Barlow lens, and this Astro-Tech Imaging Newtonian will provide you with crisp and sharply detailed close-up views of the Moon and planets.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis Astro-Tech Telescope's Optical System . . .\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eNewtonian reflector optics:\u003c\/strong\u003e 8\" aperture, 800mm focal length, f\/4 focal ratio, parabolic primary mirror; 70mm m.a. elliptical diagonal mirror. The mirrors are ground and polished under computer control for guaranteed diffraction limited performance, coated with 91% reflectivity aluminum, and overcoated with a protective layer of silicon dioxide (quartz) for long life. \u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe mirrors are made of B270 \"water white\" optical crown glass that is free of internal stress and striae. B270 glass is equivalent to BK7 in performance and optical quality. The thermal stability of B270 glass is generally better than the soda lime float glass used for the mirrors of most reflectors in this reasonable price range. For maximum contrast, the four secondary mirror spider vanes have been optimized to be as thin as possible without losing stability.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eNo-tool push-pull mirror cell:\u003c\/strong\u003e The die-cast aluminum primary mirror cell has six large hand adjust push-pull collimation knobs. These make it easy to collimate the primary mirror without tools, even while wearing gloves or mittens in cold weather. To further ease collimation, the primary mirror is precisely center-spotted. The Sky \u0026amp; Telescope review praised the \"solidly made\" primary mirror cell and secondary mirror holder.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eBuilt-in cooling fan:\u003c\/strong\u003e A low-vibration\/high CFM fan is mounted on the primary mirror cell. The fan is powered by a supplied battery pack that uses eight user-supplied AA batteries. Alternatively, the fan can be powered by a 12 VDC rechargeable battery if one is being used to power your mount's drive system.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eExtended optical tube with 15 internal baffles:\u003c\/strong\u003e To increase the contrast, the optical tube of the Astro-Tech AT8IN is extended 8.75\" forward of the focuser centerline to act as a lens shade to keep ambient light from hitting the diagonal mirror. In addition, there are 15 internal knife-edge baffles installed down the interior length of the optical tube to eliminate any stray light that might get past the extended optical tube and lower the contrast. The baffles and tube interior are finished in matte black to further absorb stray light. The result is exceptional contrast, far better than a conventional reflector for both imaging and visual observing.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe white-painted 32\" long x 9\" diameter (with 9.25\" diameter front and rear cells) Astro-Tech optical tube is fabricated of rolled steel, to allow the mirrors to cool to ambient temperature more quickly. While the rolled steel optical tube is a little heavier than a more-costly aluminum tube, the Sky \u0026amp; Telescope review points out that \"it also helps make it a very rigid setup, which is a good thing for astrophotographers.\" The scope's tube end rings are sturdy die-cast aluminum, to protect the tube during transport and provide exceptionally rigid support for the optics, \"adding to the scope's overall rigidity,\" according to the Sky \u0026amp; Telescope review.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFor essentially coma-free imaging with the AT8IN, consider adding the Astro-Tech ATCC coma corrector. This imaging accessory essentially eliminates the coma inherent in all fast focal ratio reflector telescope designs, so that the coma-free star images remain point-like all across the field.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003e2\" dual-speed Crayford focuser:\u003c\/strong\u003e The precision-made 2\" Crayford focuser drawtube ends in a 2\" accessory holder. A 1.25\" accessory adapter is standard equipment. Both the drawtube's 2\" accessory holder and the 1.25\" accessory adapter have non-marring compression ring eyepiece\/accessory holders.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe focuser has two coarse focusing knobs. One knob also has a smaller concentric knob with 10:1 ratio reduction gear microfine focusing. This provides exceptionally precise focus control during critical CCD imaging. The focus knobs have ribbed gripping surfaces so they are easy to operate, even while wearing gloves or mittens in cold weather. A drawtube tension knob on the side of the focuser lets you adjust the drag on the focuser drawtube to hold various equipment load weights while focusing. A second knob lets you lock in a precise photographic focus.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe drawtube has 34mm (1.35\") of travel. There is 80mm of back focus available from the top of the focuser's 2\" accessory holder to the image plane. A 2\" diameter x 35mm long extension tube is provided to match the back focus requirement to your particular photographic application. The 35mm extension tube has a non-marring compression ring eyepiece\/accessory holder.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eSplit tube rings:\u003c\/strong\u003e A pair of die-cast aluminum hinged split tube mounting rings are provided. Each ring has a flat boss on its underside with a 1\/4\"-20 thread mounting hole, flanked by two 4mm metric holes on 30mm centers, for installing the ring on a Vixen-style or Losmandy-style \"D-plate\" dovetail mounting plate. This lets you mount the scope on virtually any equatorial mount. In addition, there is a flat boss with a 4mm metric hole on the top of each ring. This allows you to install a separate dovetail on top of the optical tube for mounting photoguide rings and a guidescope or similar accessories piggyback on top of the AT8IN. The lightweight optical tube (18 pounds tube only; 21.6 pounds with rings and finderscope) rotates in its felt-lined die cast cradle rings to bring the focuser and finder to the most comfortable viewing position.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eFinderscope:\u003c\/strong\u003e 8x 50mm straight-through dark crosshair achromatic design, in a spring-loaded quick-release mounting bracket. The finder has a long and comfortable 13mm eye relief. To focus the finder, loosen the trim ring behind the objective lens cell, screw the lens cell in or out to focus, and tighten the trim ring to lock in the correct focus.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch2\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTech Details: \u003c\/span\u003e\u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eAperture\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e8\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBinary and Star Cluster Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eVery Good\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e800mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Ratio\u003c\/th\u003e\n\u003ctd class=\"data\"\u003ef\/4\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eGalaxy and Nebula Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eVery Good\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eHeaviest Single Component\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e18 lbs.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eHighest Useful Magnification\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e320x\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eLunar Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eGreat\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e21.6 lbs.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePlanetary Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eVery Good\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eResolution\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e0.57 arc seconds\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eVisual Limiting Magnitude\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e14\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003ch2\u003eSupplied Accessories: \u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e8 x 50mm finderscope in quick-release bracket\u003c\/li\u003e\n\u003cli\u003eCooling fan and battery pack\u003c\/li\u003e\n\u003cli\u003eHinged split tube rings\u003c\/li\u003e\n\u003cli\u003e35mm x 2\" compression ring extension tube\u003c\/li\u003e\n\u003cli\u003e2\" and 1.25\" compression ring eyepiece\/accessory holders\u003c\/li\u003e\n\u003cli\u003eDust cover\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221666902089,"sku":"AT8IN","price":549.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/17402.jpg?v=1662967805"},{"product_id":"astro-tech-vixen-style-dovetail-rail-for-mounting-accessories-on-astro-tech-at6rc-6-rc","title":"Astro-Tech Vixen-Style Dovetail Rail for Mounting Accessories on Astro-Tech AT6RC 6\" RC","description":"\u003cp\u003eThis 12.75\" long Astro-Tech accessory dovetail rail mounts on top of the Astro-Tech AT6RC 6\" Ritchey-Chrétien astrograph using existing holes in the scope's front and rear cells. The Vixen-style accessory rail duplicates the mounting rail under the AT6RC body and lets you mount optional accessories on top of the AT6RC. For example, you might install photoguide rings such as the #ATVR90, #ATVR110, or #ATVR125 for guiding the AT6RC during astrophotography using your own short focal length photoguide refractor.\u003c\/p\u003e\n\u003cp\u003eThe underside of the dovetail rail is curved to match the curvature of the AT6RC body for a solid installation. The rail has two unthreaded and countersunk 5.5mm diameter mounting holes at each end. The holes are spaced to match the spacing of the two Philips-head screws at the 12 o'clock positions in the front and rear cells of the AT6RC that help to hold the cells to the optical tube body.\u003c\/p\u003e\n\u003cp\u003eThe accessory dovetail rail is installed by removing the two screws at the 12 o'clock position from the front and rear cells of the AT6RC. There are a total of six screws in each of the front and rear cells, so the top pairs can be removed without any risk. Attach the accessory dovetail rail to the AT6RC using the newly exposed screw holes and the new flat head Philips-head screws supplied with the dovetail rail. Tighten the new screws firmly and you're done.\u003c\/p\u003e\n\u003cp\u003eIn addition to the photoguide ring sets listed above, any other optional adapter designed to fit a Vixen-style dovetail (such as the Astro-Tech #ATVA and the Losmandy #VA) can be used to mount accessories on the top of the AT6RC.\u003c\/p\u003e\n\u003cp\u003eThe dovetail rail is precision-machined of aluminum stock. It measures 12.75\" long x 65mm wide at its widest point. It is anodized dark black for durability and to match the trim color of the AT6RC. It weighs one pound.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 lb.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221668016201,"sku":"AT6SDP","price":45.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/17678.jpg?v=1662967837"},{"product_id":"astro-tech-2-extension-ring-for-a-t-ritchey-chretien-astrographs","title":"Astro-Tech 2\" Extension Ring for A-T Ritchey-Chrétien Astrographs","description":"\u003cp\u003eThis Astro-Tech 2\" long x 90mm diameter extension ring can be installed between the rear cell of an Astro-Tech Ritchey-Chrétien astrograph and its Crayford focuser to more precisely match the back focus required for your particular complement of imaging components.\u003c\/p\u003e\n\u003cp\u003eWith Astro-Tech Ritchey-Chrétiens, the scope's focuser is used by itself or (more typically) in combination with one or more of the thread-in 1\" and 2\" extension rings that are supplied with the 8\" AT8RC (optional with the 6\" AT6RC) to place the camera at the astrograph's focal plane. The weight of \u003cem\u003every \u003c\/em\u003eheavy equipment trains (camera, plus filter wheel, plus temperature-compensated electric focuser, adaptive optics system, etc.) \u003cem\u003emay \u003c\/em\u003ecause the focuser drawtube to tilt slightly when fully extended, affecting the focus.\u003c\/p\u003e\n\u003cp\u003eThe threaded 1\" and 2\" extension rings are installed singly or in combination between the astrograph's rear cell and the focuser to provide a flex-free solid metal extension that changes the distance between the focuser and the rear cell. This lets you accommodate the varying back-focus requirements of DSLR-type camera imaging versus long equipment train CCD imaging, while minimizing the need to extend the focuser drawtube.\u003c\/p\u003e\n\u003cp\u003eA little experimentation will be called for to determine what combination of extension tubes (either supplied, as with the AT8RC, or optional, as with the AT6RC) will be needed for your particular combination(s) of imaging components.\u003c\/p\u003e\n\u003cp\u003eThe ends of this extension ring have 90mm x 1mm metric threads (male on one side to thread into your existing extension rings or Crayford focuser, and female on the other to thread into your astrograph's rear cell or existing extension rings). The extension ring is machined of aluminum, anodized black. The interior has anti-reflection threading.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6.5 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003e\u003cbr\u003e\u003c\/p\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221668180041,"sku":"AT2EXT","price":34.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/17728.jpg?v=1662967842"},{"product_id":"astro-tech-10-f-8-ritchey-chretien-optical-tube","title":"Astro-Tech 10\" f\/8 Ritchey-Chrétien Optical Tube","description":"\u003cp\u003eThe 10\" Astro-Tech AT10RC Ritchey-Chrétien astrograph is a \u003cem\u003eSky \u0026amp; Telescope \u003cstrong\u003e\u003cspan style=\"font-size: 15px; font-family: verdana; color: #990000;\"\u003eHot Product for 2010\u003c\/span\u003e\u003c\/strong\u003e\u003c\/em\u003e and an \u003cstrong\u003e\u003cem\u003eAstronomy \u003cspan style=\"font-size: 15px; font-family: verdana; color: #990000;\"\u003eStar Product for 2010\u003c\/span\u003e \u003c\/em\u003e\u003c\/strong\u003eaward winner. The AT10RC is the \u003cem\u003efirst \u003c\/em\u003etruly affordable large aperture true Ritchey-Chrétien astrograph available from a U. S. company. Imitators will copy Astro-Tech's years of work, but why settle for a copy when you can get the original?\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eDeveloped by Astro-Tech to make large-format CCD imaging affordable for the amateur astronomer, the Astro-Tech AT10RC - a Sky \u0026amp; Telescope Hot Product for 2010 - is priced nearly $4000 less than the formerly least-expensive 10\" R-C. The AT10RC is the first truly affordable large aperture true Ritchey-Chrétien astrograph available from a U. S. company. Even better, despite its low price, the Astro-Tech-developed AT10RC has many of the same premium features as the high-priced competitive RCs.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis Astro-Tech AT10RC Ritchey-Chrétien astrograph has:\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 10\" f\/8 true Ritchey-Chrétien hyperbolic mirror optical design\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• low thermal expansion quartz primary and secondary mirrors \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• nine contrast-enhancing main tube knife edge light baffles \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• dual-speed 3\" linear bearing Crayford focuser\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• three built-in cooling fans in rear cell \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 1.25\" and 2\" compression ring accessory holders \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 1\" and 2\" focuser extension rings to fine-tune the back focus\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• two Losmandy-style \"D-plate\" dovetail rails \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• mounting bracket for optional finder\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The result of several years of Astro-Tech's joint development with the manufacturer, the Astro-Tech 10\" f\/8 AT10RC Ritchey-Chrétien is the first truly affordable large aperture true Ritchey-Chrétien astrograph available from a U. S. company. Imitators have copied Astro-Tech's years of hard development work, but why settle for a copy when you can get the original? Sky \u0026amp; Telescope agrees, as they named the Astro-Tech AT10RC a Sky \u0026amp; Telescope Hot Product for 2010, along with its smaller 8\" brother, the Astro-Tech AT8RC. (Incidentally, the original Astro-Tech 6\" R-C was named a Sky \u0026amp; Telescope Hot product for 2009.)\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eAstronomy named the Astro-Tech AT10RC a Star Product for 2010, saying \"it offers premium features . . . a superb photographic telescope . . . Astronomy Technologies breaks the price barrier with affordable Ritchey-Chrétiens.\"\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The affordable Astro-Tech AT10RC joins two other Astro-Tech Ritchey-Chrétien firsts. One is the AT8RC, also a Sky \u0026amp; Telescope Hot Product for 2010 - the first 8\" true Ritchey-Chrétien astrograph available from a U. S. company and the first and still the only affordable U. S. 8\" R-C with Astro-Tech-designed premium features like quartz mirrors, dielectric mirror coatings, two dovetail mounting rails, and more. The other is the AT6RC - a highly affordable R-C astrograph for DSI and DSLR imaging that was conceived and developed by, and first brought to market by, Astro-Tech and named a Hot Product for 2009. Both the AT6RC and the AT8RC were highly praised in a four-page review in the December 2009 issue of Sky \u0026amp; Telescope magazine.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eAnd we are serious when we say the 10\" aperture AT10RC is \"affordable.\" The Astro-Tech AT10RC is priced nearly $4000 less than the formerly least-expensive 10\" R-C. As Sky \u0026amp; Telescope pointed out in their Hot Product citation in the January 2010 Sky \u0026amp; Telescope, \"Ritchey-Chrétien reflectors are highly regarded among today's elite astrophotographers, and premium instruments often carry price tags starting at about $1,000 per inch of aperture. So it's the best kind of \"sticker shock\" to see the prices for Astro-Tech's 8- and 10-inch f\/8 Ritchey-Chrétiens, which pack features too numerous to list here. Our review of the 8-inch scope appears in last month's issue (December 2009), page 38, and our initial hands-on look at the 10-inch suggests that it will be equally exciting for deep sky astrophotographers.\" The magazine also pointed out that the AT10RC cost \"about one-fourth what similar instruments did just a couple of years ago.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003c\/span\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe Ritchey-Chrétien optical design is used in virtually every recent large mega-million dollar professional observatory telescope - including the Hubble Space Telescope The Astro-Tech AT10RC astrograph (a telescope designed specifically for photographing comparatively wide areas of the sky) makes the coma-free imaging of true Ritchey-Chrétien imaging optics available to the DSLR and large format CCD astrophotographer at a price less than that of many large format CCD cameras. Featuring first-quality 99% reflectivity dielectric mirror coatings and premium low thermal expansion quartz mirrors, this economical 10\" Astro-Tech R-C makes you wonder just what competitive high-price R-Cs have that makes them cost so much more.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eDesigned for exceptional imaging, the Astro-Tech AT10RC provides the wide coma-free photographic field that large format CCD astrophotographers crave, but can't get from conventional reflectors and Schmidt-Cassegrains. Likewise, as a pure two-mirror system, the AT10RC is totally free from the spurious color that affects the imaging of all but the most costly apochromatic refractors, and it does it with an 10\" aperture that dwarfs the light gathering of most apo refractors.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe AT10RC photos of the Eagle and Trifid Nebulas are from AT10RC prototype owner John O'Neill. They were taken with an SBIG ST-10XME CCD camera and Astrodon filters.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eJohn had this to say about the AT10RC, \"Finally got a full data image of an old favorite, The Trifid Nebula. Total of 1.5 hours of data on a 7 out of 10 night here in Florida. The scope is truly everything I expected and more. This shot was compared to one taken with a 24\" RC (taken the same night) and you would be hard pressed to tell the difference. The guy that had the 24\" was actually a little miffed that a $3,000 scope could do as well as his $75,000 scope :\u0026gt;)\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eAnother good example of why that high-end 24\" R-C owner might be miffed is Brian Kimball's exceptional image of NGC2244. This open cluster of young stars is nestled within the Rosette Nebula, and was recently formed from that nebula's material. Brian's image easily stands up to a side by side comparison with photos taken by professional observatories using much larger and more expensive telescopes, as well as to those taken with the most expensive amateur astrographs.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eIf serious astrophotography is your goal, but the price of most true Ritchey-Chrétien optics has been keeping you from the optical design most modern professional observatories and the Hubble Space Telescope use for their imaging, your wait is over. The 10\" S \u0026amp; T Hot Product for 2010 Astro-Tech AT10RC astrograph can bring the world of professional DSLR\/CCD deep space imaging to your backyard observatory at a truly affordable price.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFeatures of this Astro-Tech AT10RC Astrograph . . .\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptical design:\u003c\/strong\u003e true Ritchey-Chrétien Cassegrain-type two-mirror optics, with hyperbolic primary and secondary mirrors. For more details, click on the \"optics\" icon above. The 235mm available back focus allows for the use of long CCD equipment trains.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptical specifications:\u003c\/strong\u003e 10\" aperture, 2000mm focal length, f\/8 focal ratio.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid primary mirror:\u003c\/strong\u003e Made of low thermal expansion quartz, rather than the Pyrex used by competitors. Ground and polished under precision computer control. Unlike catadioptric designs (SCTs, Maksutovs, etc.) that move the primary mirror fore and aft in the optical tube to focus (which can lead to image shift as the mirror position changes) the AT10RC primary mirror is fixed to eliminate both a catadioptric's image shift and the frequent primary mirror collimation requirements of a Newtonian reflector.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid secondary mirror:\u003c\/strong\u003e Made of low thermal expansion quartz, rather than the Pyrex used by competitors. Ground and polished under precision computer control. Mounted in a four-vane spider and fully collimatable using simple standard Cassegrain reflector collimating techniques. Unlike complicated R-C designs that use motors to move the secondary mirror fore and aft to focus, the AT10RC secondary mirror is fixed and focusing is done externally.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The December 2009 issue of Sky \u0026amp; Telescope said that the Astro-Tech R-C's fixed primary and secondary mirrors \"eliminate image shift, which has been the bane of Cassegrain scopes with moving-mirror focusing systems . . . It also keeps the effective focal length of the system constant, and the infinity focal point remains at a fixed point outside of the telescope, neither of which is the case with moving-mirror systems that change the separation between a Cassegrain's primary and secondary mirrors.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003c\/span\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eRolled steel optical tube:\u003c\/strong\u003e The optical tube is made of thin rolled steel for strength, with die-cast and machined front and rear cells. In addition to its strength, the thermal expansion characteristics of steel are quite low, much closer to carbon fiber than to aluminum. In most environments, this results in fewer focus changes due to the optical tube contracting as the temperature drops during an imaging session than you need with an aluminum body scope. For areas where extreme temperature swings are the norm, a very low thermal expansion carbon fiber body version of the AT10RC (the AT10RCF) is available to still further lessen the need for adjusting the focus over the course of an imaging session.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eMultiple internal light baffles:\u003c\/strong\u003e Computer optimized primary and secondary baffling. Nine contrast-enhancing glare-stop knife-edge baffles in the optical tube; multiple glare-stop microbaffles in the secondary mirror light shield; and baffles in the primary mirror baffle tube to provide truly dark sky backgrounds during imaging.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eDual-speed 3.3\" linear bearing Crayford focuser:\u003c\/strong\u003e A newly-designed extra-sturdy \"linear bearing\" Crayford focuser is threaded onto the rear cell of the AT10RC. A locking collar allows the entire precision-made non-vignetting focuser to be rotated to the most convenient imaging angle and locked in place. There is 140mm (5.5\") of back focus available with the focuser installed (235mm from the rear cell of the scope, without focuser, to the focal plane).\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The focuser has dual-speed focusing. There are two coarse focusing knobs. The right knob also has a smaller concentric knob with a 10:1 reduction gear microfine focusing ratio. This provides exceptionally precise image control during critical imaging. All focus knobs are ribbed, so they are easy to operate, even while wearing gloves or mittens in cold weather. A lock knob underneath the focuser lets you adjust the tension on the drawtube to accommodate varying equipment loads. A large lock knob on top of the focuser lets you lock in your photographic focus.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe new linear bearing focuser has a polished stainless steel drive rail that runs the length of the underside of the drawtube. The focuser's stainless steel drive shaft presses on this drive rail to move the focuser, rather than having the hard steel drive shaft press directly on (and wear out) the softer aluminum drawtube as with conventional Crayford focusers. The steel drive rail rides in a self-lubricating track that extends almost the entire length of the focuser body. The drive rail and its attached drawtube are thereby supported over most of their length at all times, rather than by a conventional Crayford focuser's two sets of small contact area roller bearings. This system distributes the drive force evenly over the entire drawtube, without concentrating it on a few small contact points. The result is a very rigid drawtube with essentially zero flexure and no wear (much less flat spots or uneven wear) on the focuser drawtube.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTo fine-tune the long back focus of the AT10RC to the requirements of your camera and equipment train, three threaded extension rings (two 1\" in length and one 2\") are provided to install singly or in combination between the AT10RC rear cell and the focuser. These provide a flex-free solid metal extension that changes the distance between the focuser and the rear cell. This lets you accommodate the varying back-focus requirements of DSLR-type camera imaging versus long equipment train CCD imaging. The two 6.4 ounce 1\" extension rings and the 14.4 ounce 2\" ring add 1.7 pounds to the weight of the scope when all rings are installed.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFor even more impressive coma-free imaging with the AT8RC, consider adding the Astro-Tech AT2FF field flattener. While not specifically designed to work with Ritchey-Chrétien astrographs, images taken with the field flattener by Astro-Tech R-C owners have shown that the Astro-Tech 2\" field flattener works remarkably well with these advanced coma-free reflectors as well as with refractors. This modestly-priced imaging accessory essentially eliminates the residual field curvature inherent in all reflector telescope designs, so that the coma-free star images remain point-like all across the field. An optical analysis and ray tracing of the field flattener was done in ZEMAX and applied to the R-Cs by Roger Ceragioli, the noted optical designer who did the final optimization of the Astro-Tech Ritchey-Chrétien optics. Here is what he had to say about the #AT2FF, \"My conclusion, which seems supported by what users are saying, is that you don't need any other field flattener. This one performs well over a 40mm image circle in all three small RCs (6\", 8\", and 10\").\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eFocusing scale:\u003c\/strong\u003e The focuser's 50mm (1.97\") travel drawtube has scales marked in both 1\/16th inch and 1mm increments so you can note individual focuser positions for easy return to the approximate correct focus when switching between varying photographic equipment combinations.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eCooling fans:\u003c\/strong\u003e To allow the AT10RC to reach ambient temperatures more quickly for optimum imaging performance, there are three small low vibration\/high CFM primary mirror cooling fans built into the rear cell. The high speed DC fans are powered by a standard equipment battery pack that plugs into a jack on the rear cell. The battery pack uses eight user-supplied AA batteries. An optional external DC power supply, such as a rechargeable 12VDC battery pack can also be used to power the fans.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003e1.25\" and 2\" compression ring accessory holders:\u003c\/strong\u003e The 3.25\" o.d. focuser drawtube ends in a stepdown to a 2\" accessory holder that uses a non-marring soft brass compression ring to hold 2\" imaging accessories in place. The compression ring won't scratch the barrel of your accessories as an ordinary thumbscrew can. Two thumbscrews are provided to lock the compression ring on your accessories. Also supplied is a 1.25\" accessory holder that slips into the 2\" compression ring holder to let you use 1.25\" imaging accessories. Like the 2\" accessory holder on the drawtube, the 1.25\" adapter also uses a non-marring soft brass compression ring.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eTwo dovetail mounting rails:\u003c\/strong\u003e Two Losmandy-style \"D-plate\" dovetail rails are provided for installing the AT10RC on an equatorial mount, as well as for mounting optional accessories (such as rings for a photoguide scope) on top. The 21\" long dovetail rails run the length of the optical tube. One is mounted underneath the tube for installing the 34.4 pound AT10RC directly on a suitable payload capacity Losmandy-style equatorial mount. The second dovetail rail is mounted 180° away from the first, on top of the tube. This can be used for installing a photoguide ring set, piggyback camera adapter, or any other accessory that attaches to a scope by means of Losmandy-style \"D-plate\" dovetail adapters. The undersides of the dovetails have been hollowed out to lighten their weight without compromising their strength, as can be seen in the side-view feature image below.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eFinderscope dovetail:\u003c\/strong\u003e a Vixen-style finderscope bracket dovetail base is installed on the upper left side of the optical tube. It can easily be removed if not needed. It will accept Vixen-style finderscope brackets as well as red dot-type finders, such as the Astro-Tech #ATF.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOther accessories:\u003c\/strong\u003e A snap-in dust cap is standard.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch2\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTech Details: \u003c\/span\u003e\u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eAperture\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e10\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBinary and Star Cluster Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e2000mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Ratio\u003c\/th\u003e\n\u003ctd class=\"data\"\u003ef\/8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eGalaxy and Nebula Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eLunar Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e34.4 lbs.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePlanetary Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eResolution\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e0.46 arc seconds\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBack Focus\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e9.25 (235mm) from rear cell, 5 (127mm) with focuser installed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003ch2\u003eSupplied Accessories: \u003c\/h2\u003e\n\u003cp\u003e\u003cmeta charset=\"UTF-8\"\u003e\u003cstrong\u003e• three built-in cooling fans in rear cell \u003cbr\u003e• 1.25\" and 2\" compression ring accessory holders \u003cbr\u003e• 1\" and 2\" focuser extension rings to fine-tune the back focus\u003cbr\u003e• two Losmandy-style \"D-plate\" dovetail rails \u003cbr\u003e• mounting bracket for optional finder \u003c\/strong\u003e\u003c\/p\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221668507721,"sku":"AT10RC","price":2495.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/17788.jpg?v=1662967854"},{"product_id":"astro-tech-7-short-universal-dovetail-plate-for-vixen-style-mounts-black","title":"Astro-Tech 7\" Short Universal Dovetail Plate for Vixen-Style Mounts, Black","description":"\u003cp\u003eThis black-anodized 7\" Astro-Tech short universal dovetail plate fits the dovetail slot of the Vixen-style saddle used on current Vixen and Vixen-style altazimuth and German equatorial mounts. Such mounts include the Astro-Tech Voyager altazimuth; Celestron CG-5 and Advanced Series equatorial mounts; Meade LXD-75 equatorial mount; and Vixen Polaris, Great Polaris, and Sphinx equatorials, or Porta altazimuth mounts.\u003c\/p\u003e\n\u003cp\u003eThe Astro-Tech universal dovetail is designed primarily to hold the mounting rings of short focal length Astro-Tech, TeleVue, Parks, Takahashi, and Meade refractors, plus those of the smaller Astro-Tech, Questar, Meade, and Celestron catadioptric optical tubes.\u003c\/p\u003e\n\u003cp\u003eThe dovetail has two unthreaded 6.9mm diameter mounting holes at the ends of the dovetail and a 0.25\" wide x 5\" long slot on the plate's centerline for attaching rings and other accessories using 1\/4\"-20 or metric bolts. The configuration of the slot and mounting holes is shown in the engineering drawing in the feature image below. This combination of the slot and the mounting holes allows you to install virtually any configuration of mounting rings.\u003c\/p\u003e\n\u003cp\u003eThe underside of the dovetail is routed out to a depth of 10mm so that the mounting holes and slots are all effectively countersunk into the underside of the dovetail. This assures that the heads of the bolts holding the mounting rings will not protrude and keep the dovetail plate from sliding back and forth in the mount saddle for balancing.\u003c\/p\u003e\n\u003cp\u003eThere is also a 1\/4\"-20 thread hole at each end of the plate. This lets you install 1\/4\"-20 bolts in the holes to act as safety stops. These will keep the dovetail from sliding out of the mount saddle unexpectedly should the mount's locking knob loosen accidentally.\u003c\/p\u003e\n\u003cp\u003eThe 5\/8\" thick dovetail is precision-machined of aluminum stock. It measures 15\" long x 42mm wide at its widest point (36mm wide across the top ring mounting surface) and is hard-anodized black for durability. It weighs 6.4 ounces.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6.4 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003e\u003cbr\u003e\u003c\/p\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221668704329,"sku":"ATVUPSB","price":30.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/17840.jpg?v=1662967859"},{"product_id":"astro-tech-10-f-8-ritchey-chretien-carbon-fiber-optical-tube","title":"Astro-Tech 10\" f\/8 Ritchey-Chrétien Carbon Fiber Optical Tube","description":"\u003cp\u003eAfter many customer requests, we are proud to now offer the Astro-Tech AT10RC Ritchey-Chrétien astrograph, a \u003cem\u003eSky and Telescope Hot Product for 2010, \u003c\/em\u003ewith a premium low thermal expansion carbon fiber body. The AT10RC is the first truly affordable large aperture true Ritchey-Chrétien astrograph available from a U. S. company, and is priced thousands of dollars less than competitive 10\" RCs.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eDeveloped by Astro-Tech to make large-format CCD imaging affordable for the amateur astronomer, the Astro-Tech AT10RCF - a Sky \u0026amp; Telescope Hot Product for 2010 - is priced thousands of dollars less than the formerly least-expensive 10\" R-C. The Astro-Tech AT10RCF is the first truly affordable large aperture true Ritchey-Chrétien astrograph available from a U. S. company. Even better, despite its low price, the Astro-Tech-developed AT10RCF has many of the same premium features as the much higher-priced competitive RCs (and some they don't have) - like quartz mirrors, carbon fiber body, and more.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis Astro-Tech AT10RCF Ritchey-Chrétien astrograph has: \u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 10\" f\/8 true Ritchey-Chrétien hyperbolic mirror optical design\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• low thermal expansion quartz primary and secondary mirrors \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• center spotted secondary mirror \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• low thermal expansion carbon fiber optical tube \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• nine contrast-enhancing main tube knife edge light baffles \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• shipped without focuser to allow you to add the premium focuser of your choice \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 1\" and 2\" focuser extension rings to fine-tune the back focus of your optional focuser \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• three built-in cooling fans in rear cell \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• two Losmandy-style \"D-plate\" dovetail rails \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• mounting bracket for optional finder\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe 10\" Astro-Tech AT10RCF is the first truly affordable carbon fiber large aperture true Ritchey-Chrétien astrograph available from a U. S. company. Imitators will no doubt copy Astro-Tech's years of hard development work, but why settle for a copy when you can get the original? Sky \u0026amp; Telescope agrees, as they named the Astro-Tech 8\" and 10\" Astro-Tech Ritchey-Chrétien astrographs Sky \u0026amp; Telescope Hot Products for 2010. (Incidentally, the original Astro-Tech 6\" R-C was named a Sky \u0026amp; Telescope Hot product for 2009 and the new 12\" AT12RC has been named a Hot Product for 2011.)\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe surprisingly affordable Astro-Tech AT10RCF (and its even more affordable metal tube brother, the AT10RC) joins two other Astro-Tech Ritchey-Chrétien firsts. One is the AT8RC, a Sky \u0026amp; Telescope Hot Product for 2010 - the first 8\" true Ritchey-Chrétien astrograph available from a U. S. company and the first and still the only affordable U. S. 8\" R-C with Astro-Tech-designed premium features like quartz mirrors, two dovetail mounting rails, and more. The other is the AT6RC - a highly affordable R-C astrograph for webcam, DSI, and DSLR imaging that was conceived and developed by, and first brought to market by, Astro-Tech and named a Hot Product for 2009. Both the AT6RC and the AT8RC were highly praised in a four-page review in the December 2009 issue of Sky \u0026amp; Telescope magazine.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eAnd we are serious when we say the 10\" aperture AT10RCF is \"affordable.\" The premium feature carbon fiber Astro-Tech AT10RCF is priced thousands of dollars less than the formerly least-expensive phenolic tube 10\" R-C. As Sky \u0026amp; Telescope pointed out in their Hot Product citation in the January 2010 Sky \u0026amp; Telescope, \"Ritchey-Chrétien reflectors are highly regarded among today's elite astrophotographers, and premium instruments often carry price tags starting at about $1,000 per inch of aperture. So it's the best kind of \"sticker shock\" to see the prices for Astro-Tech's 8- and 10-inch f\/8 Ritchey-Chrétiens, which pack features too numerous to list here. Our review of the 8-inch scope appears in last month's issue (December 2009), page 38, and our initial hands-on look at the 10-inch suggests that it will be equally exciting for deep sky astrophotographers.\" The magazine also pointed out that the 10\" Astro-Tech RC cost \"about one-fourth what similar instruments did just a couple of years ago.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe Ritchey-Chrétien optical design is used in virtually every recent large mega-million dollar professional observatory telescope - including the Hubble Space Telescope. The Astro-Tech AT10RCF astrograph (a telescope designed specifically for astronomical imaging, rather than visual observing) makes the coma-free imaging of true Ritchey-Chrétien optics available to the DSLR and large format CCD astrophotographer at a price less than that of many large format CCD cameras and DSLR camera bodies. Featuring first-quality premium low thermal expansion quartz mirrors, rather than aluminized Pyrex glass mirrors, this economical 10\" Astro-Tech carbon fiber R-C makes you wonder just what competitive high-price R-Cs have that makes them cost so much more.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eDesigned for exceptional imaging, the Astro-Tech AT10RCF provides the coma-free photographic field that large format CCD astrophotographers crave, but can't get from conventional reflectors and Schmidt-Cassegrains. Likewise, as a pure two-mirror system, the AT10RCF has a wide spectral response and is totally free from the spurious color that affects the imaging of all but the most costly apochromatic refractors, and it does it with an 10\" aperture that dwarfs the light gathering of most apo refractors.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eAn example of the kind of imaging possible with the AT10RCF is Brian Kimball's exceptional image of NGC2244. This open cluster of young stars is nestled within the Rosette Nebula, and was recently formed from that nebula's material. Brian's AT10RCF image easily stands up to a side by side comparison with photos taken by professional observatories using much larger and more expensive telescopes, as well as to those taken with the most expensive amateur astrographs.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eIf serious astrophotography is your goal, but the price of most true Ritchey-Chrétien optics has been keeping you from the optical design used by most modern professional observatories and the Hubble Space Telescope for their imaging, your wait is over. The 10\" Sky \u0026amp; Telescope Hot Product for 2010 Astro-Tech AT10RCF astrograph can bring the world of professional DSLR\/CCD deep space imaging to your backyard observatory at a truly affordable price.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFeatures of this Astro-Tech AT10RCF Astrograph . . .\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptical design:\u003c\/strong\u003e True Ritchey-Chrétien Cassegrain-type two-mirror optics, with hyperbolic primary and secondary mirrors. For more details, click on the \"optics\" icon above. The 235mm available back focus allows for the use of long CCD equipment trains.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptical specifications:\u003c\/strong\u003e 10\" aperture, 2000mm focal length, f\/8 focal ratio.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid primary mirror:\u003c\/strong\u003e Made of low thermal expansion quartz, rather than the Pyrex used by competitors. Ground and polished under precision computer control. Unlike catadioptric designs (SCTs, Maksutovs, etc.) that move the primary mirror fore and aft in the optical tube to focus (which can lead to image shift as the mirror position changes) the AT10RCF primary mirror is fixed to eliminate both a catadioptric's image shift and the frequent primary mirror collimation requirements of a Newtonian reflector. Collimation is pre-set at the factory but can be adjusted, if needed, using three traditional push\/pull locking adjustment screw sets.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid secondary mirror:\u003c\/strong\u003e Made of low thermal expansion quartz, rather than the Pyrex used by competitors. Ground and polished under precision computer control. Mounted in a four-vane spider and fully collimatable using simple standard Cassegrain reflector collimating techniques. The secondary mirror is precisely center-spotted to make collimation easier. Unlike complicated R-C designs that use motors to move the secondary mirror fore and aft to focus, the AT10RCF secondary mirror is fixed and focusing is done externally.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The December 2009 issue of Sky \u0026amp; Telescope said that the Astro-Tech R-C's fixed primary and secondary mirrors \"eliminate image shift, which has been the bane of Cassegrain scopes with moving-mirror focusing systems . . . It also keeps the effective focal length of the system constant, and the infinity focal point remains at a fixed point outside of the telescope, neither of which is the case with moving-mirror systems that change the separation between a Cassegrain's primary and secondary mirrors.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eMultiple internal light baffles:\u003c\/strong\u003e Computer optimized primary and secondary baffling. Nine contrast-enhancing glare-stop knife-edge baffles in the optical tube; multiple glare-stop microbaffles in the secondary mirror light shield; baffles in the primary mirror baffle tube, and baffles in the focuser drawtube, provide truly dark sky backgrounds during imaging.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eCarbon fiber optical tube:\u003c\/strong\u003e Made of a high strength woven carbon fiber-reinforced epoxy-coated composite with extremely low thermal expansion characteristics to reduce the possibility of temperature-related focus changes during an exposure that can occur with aluminum or rolled steel tube systems. Die-cast and machined aluminum front and rear cells. The carbon fiber tube is dent-proof and virtually indestructible. Carbon fiber composites are so strong that the new $200,000,000 Boeing 787 Dreamliner passenger jet will use a wing and fuselage made almost entirely out of carbon fiber.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The December 2009 issue of Sky \u0026amp; Telescope said of the carbon fiber tube used in the 8\" Astro-Tech RC, \"the carbon-fiber tube did a good job of holding focus over the modest temperature changes occurring during my summer evenings. More telling, perhaps, was the scope's tendency to remain accurately focused after several days of inactivity during which the temperature in my backyard observatory would cycle over a huge range.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eDual-speed 3.3\" linear bearing Crayford focuser:\u003c\/strong\u003e A newly-designed extra-sturdy \"linear bearing\" Crayford focuser is threaded onto the rear cell of the AT10RCF. A locking collar allows the entire precision-made non-vignetting focuser to be rotated to the most convenient imaging angle and locked in place. There is 140mm (5.5\") of back focus available with the focuser installed (235mm from the rear cell of the scope, without focuser, to the focal plane).\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The focuser has dual-speed focusing. There are two coarse focusing knobs. The right knob also has a smaller concentric knob with a 10:1 reduction gear microfine focusing ratio. This provides exceptionally precise image control during critical imaging. All focus knobs are ribbed, so they are easy to operate, even while wearing gloves or mittens in cold weather. A lock knob underneath the focuser lets you adjust the tension on the drawtube to accommodate varying equipment loads. A large lock knob on top of the focuser lets you lock in your photographic focus.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe new linear bearing focuser has a polished stainless steel drive rail that runs the length of the underside of the drawtube. The focuser's stainless steel drive shaft presses on this drive rail to move the focuser, rather than having the hard steel drive shaft press directly on (and wear out) the softer aluminum drawtube as with conventional Crayford focusers. The steel drive rail rides in a self-lubricating track that extends almost the entire length of the focuser body. The drive rail and its attached drawtube are thereby supported over most of their length at all times, rather than by a conventional Crayford focuser's two sets of small contact area roller bearings. This system distributes the drive force evenly over the entire drawtube, without concentrating it on a few small contact points. The result is a very rigid drawtube with essentially zero flexure and no wear (much less flat spots or uneven wear) on the focuser drawtube.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTo fine-tune the long back focus of the AT10RCF to the requirements of your camera and equipment train, three threaded extension rings (two 1\" in length and one 2\") are provided to install singly or in combination between the AT10RC rear cell and the focuser. These provide a flex-free solid metal extension that changes the distance between the focuser and the rear cell. This lets you accommodate the varying back-focus requirements of DSLR-type camera imaging versus long equipment train CCD imaging. The two 6.4 ounce 1\" extension rings and the 14.4 ounce 2\" ring add 1.7 pounds to the weight of the scope when all rings are installed.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptional field flattener:\u003c\/strong\u003e For even more impressive coma-free imaging with the AT10RCF, consider adding the Astro-Tech AT2FF field flattener. While not specifically designed to work with Ritchey-Chrétien astrographs, images taken with the field flattener by Astro-Tech R-C owners have shown that the Astro-Tech 2\" field flattener works remarkably well with these advanced coma-free reflectors as well as with refractors. This modestly-priced imaging accessory essentially eliminates the residual field curvature inherent in all reflector telescope designs, so that the coma-free star images remain point-like all across the field. An optical analysis and ray tracing of the field flattener was done in ZEMAX and applied to the R-Cs by Roger Ceragioli, the noted optical designer who did the final optimization of the Astro-Tech Ritchey-Chrétien optics. Here is what he had to say about the #AT2FF, \"My conclusion, which seems supported by what users are saying, is that you don't need any other field flattener. This one performs well over a 40mm image circle in all three small RCs (6\", 8\", and 10\").\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eCooling fans:\u003c\/strong\u003e To allow the AT10RCF to reach ambient temperatures more quickly for optimum imaging performance, there are three small low vibration\/high CFM primary mirror cooling fans built into the rear cell. The high speed DC fans are powered by a standard equipment battery pack that plugs into a jack on the rear cell. The battery pack uses eight user-supplied AA batteries. An optional external DC power supply, such as a rechargeable 12VDC battery pack can also be used to power the fans.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eTwo dovetail mounting rails:\u003c\/strong\u003e Two Losmandy-style \"D-plate\" dovetail rails are provided for installing the AT10RCF on an equatorial mount, as well as for mounting optional accessories (such as rings for a photoguide scope) on top. The 21\" long dovetail rails run the length of the optical tube. One is mounted underneath the tube for installing the 33.6 pound AT10RCF directly on a suitable payload capacity Losmandy-style equatorial mount. The second dovetail rail is mounted 180° away from the first, on top of the tube. This can be used for installing a photoguide ring set, piggyback camera adapter, or any other accessory that attaches to a scope by means of Losmandy-style \"D-plate\" dovetail adapters. The undersides of the dovetails have been hollowed out to lighten their weight without compromising their strength, as can be seen in the side-view feature image below.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eFinderscope dovetail:\u003c\/strong\u003e A Vixen-style finderscope bracket dovetail base is installed on the upper left side of the optical tube's rear cell. It can easily be removed if not needed. It will accept Vixen-style finderscope brackets as well as red dot-type finders, such as the Astro-Tech #ATF.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOther accessories:\u003c\/strong\u003e A snap-in dust cap is standard.\u003c\/span\u003e\u003c\/p\u003e\n\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eAperture\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e10\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBinary and Star Cluster Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e2000mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Ratio\u003c\/th\u003e\n\u003ctd class=\"data\"\u003ef\/8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eGalaxy and Nebula Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eLunar Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e33.6 lbs.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePlanetary Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eResolution\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e0.46 arc seconds\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTelescope Type\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eRitchey-Chrétien\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBack Focus\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e9.25 (235mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003ch2\u003eSupplied Accessories: \u003c\/h2\u003e\n\u003cp\u003e\u003cmeta charset=\"UTF-8\"\u003e\u003cstrong\u003e• 1\" and 2\" focuser extension rings to fine-tune the back focus of your \u003cem\u003eoptional \u003c\/em\u003efocuser \u003cbr\u003e• three built-in cooling fans in rear cell \u003cbr\u003e• two Losmandy-style \"D-plate\" dovetail rails \u003cbr\u003e• mounting bracket for optional finder \u003c\/strong\u003e\u003c\/p\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221669130313,"sku":"AT10RCF","price":3495.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/18196.jpg?v=1662967873"},{"product_id":"astro-tech-cordless-illuminator","title":"Astro-Tech Cordless Illuminator","description":"\u003cp\u003eThis very economical Astro-Tech #ATIL cordless illuminator is used in the 10x50mm Astro-Tech illuminated reticle finderscopes and in the Astro-Tech #AT24IL illuminated centering eyepiece. It can also be used in the Celestron 10mm Plössl crosshair reticle guiding eyepiece (and most other manufacturers' illuminated reticles that use an illuminator with an 8mm nosepiece). It is available here as a replacement for a broken, lost, or stolen illuminator from such a finderscope or eyepiece.\u003c\/p\u003e\n\u003cp\u003eThe battery-operated illuminator has a metal body with an adjustable brightness red LED (light emitting diode). There is a combined on\/off switch and variable brightness control at one end. The other end has a male threaded nosepiece to fit illuminated reticles with a standard 8mm female thread illuminator port. Two supplied 1.5V watch\/camera\/calculator button batteries will power the illuminator for many hours of use. The supplied batteries are model GPA76, but you can also use the Duracell, Maxell, National, Panasonic, Sony, or Toshiba LR44; the Eveready or Philips A76; etc. When replacing batteries, be sure the battery - signs face the LED portion of the illuminator and the + signs face the on\/off switch.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003ePlease note: \u003c\/strong\u003eWhile the manufacturer normally supplies batteries at no cost with this product as a convenience, the battery charge or useful life is not guaranteed. The batteries may arrive with their charge depleted or very low. In such a case, you will have to purchase replacement batteries locally, as battery life is not covered by the manufacturer's warranty.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221669228617,"sku":"ATIL","price":29.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/18271.jpg?v=1662967874"},{"product_id":"astro-tech-24mm-illuminated-reticle-eyepiece","title":"Astro-Tech 24mm Illuminated Reticle Eyepiece","description":"\u003cp\u003eThe economical Astro-Tech #AT24IL illuminated reticle 1.25\" eyepiece helps you align your go-to telescope on the sky, check your polar alignment for astrophotography, center guide stars in an photoguide scope, and more . . .\u003c\/p\u003e\n\u003cp\u003eThis Astro-Tech #AT24IL illuminated reticle 1.25\" eyepiece is the perfect eyepiece for aligning go-to telescopes on the sky each night when you go out to observe. It is also ideal for checking your scope's polar alignment for long exposure astrophotography, for centering guide stars in an off-axis photoguide scope for astrophotography, or for testing the accuracy of your computer pointing or the periodic error of your tracking system. Priced as much as 40% less than competitive illuminated reticle eyepieces, the #AT24IL is yet another example of the Astro-Tech philosophy of \"more performance for less money.\"\u003c\/p\u003e\n\u003cp\u003eMost conventional illuminated reticle eyepieces have a short focal length and limited eye relief, which can make for uncomfortable viewing, particularly if you wear eyeglasses. In comparison, the Astro-Tech #AT24IL has a long 24mm focal length for a wider field that makes it easier to locate guide stars. This virtually eliminates the need to swap out a high-power illuminated reticle with a lower power eyepiece to locate or center objects.\u003c\/p\u003e\n\u003cp\u003eIts very long 20mm eye relief and soft roll-down rubber eyecup make it very comfortable to use, whether you wear glasses to observe or not. You can use this Astro-Tech 1.25\" eyepiece with any make or model of telescope or off-axis guidescope.\u003c\/p\u003e\n\u003cp\u003eThe eyepiece reticle has a single etched crosshair precisely centered in eyepiece field of view for accurate results. A ribbed ring at the top of the eyepiece rotates to focus the crosshairs sharply to match your eyesight. The five-element optical system is fully multi-coated on all air-to-glass surfaces with high transmission anti-reflection coatings for bright, crisp views. The edges of the lenses are blackened for high contrast. The barrel is threaded for standard 1.25\" filters.\u003c\/p\u003e\n\u003cp\u003eThe metal-body cordless red LED (light emitting diode) crosshair illuminator has a rotary on\/off switch with an integral brightness level control. Two supplied 1.5V watch\/camera\/calculator button batteries will power the illuminator for many hours of use. The supplied batteries are model GPA76, but you can also use the Duracell, Maxell, National, Panasonic, Sony, or Toshiba LR44; the Eveready or Philips A76; etc. When replacing batteries, be sure the battery - signs face the LED portion of the illuminator and the + signs face the on\/off switch.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003ePlease note: \u003c\/strong\u003eWhile the manufacturer normally supplies batteries at no cost with this product as a convenience, the battery charge or useful life is not guaranteed. The batteries may arrive with their charge depleted or very low. In such a case, you will have to purchase replacement batteries locally, as battery life is not covered by the manufacturer's warranty.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eEye Relief\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e20mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eField of view\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e50\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e24mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e4 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221669294153,"sku":"AT24IL","price":69.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/18407.jpg?v=1662967878"},{"product_id":"astro-tech-at65edq-65mm-f-6-5-ed-quadruplet-astrograph","title":"Astro-Tech AT65EDQ 65mm f\/6.5 ED quadruplet astrograph - Discontinued","description":"\u003cp\u003e\u003cspan style=\"color: #ff0000;\"\u003e\u003cstrong\u003eTHIS PRODUCT HAS BEEN DISCONTINUED.  THIS PAGE IS HERE FOR INFORMATIONAL PURPOSES ONLY.\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003eThis unique Astro-Tech apochromatic dual ED quadruplet fast focal ratio refractor uses an ED triplet objective lens, plus a built-in ED singlet lens field flattener, to give you exceptional flat field\/very wide field imaging capabilities at an affordable price . . .\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"color: #ff0000;\"\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTHIS PRODUCT HAS BEEN DISCONTINUED.  THIS PAGE IS HERE FOR INFORMATIONAL PURPOSES ONLY.\u003c\/span\u003e\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis Astro-Tech AT65EDQ ED refractor astrograph has:\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 65mm f\/6.5 fully multicoated four-lens\/two-group (triplet\/singlet) refractor\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• two ED lens elements, including an FPL-53 element in the objective\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 110mm of backfocus\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• amazing flat field astrophotographic capabilities and a 44mm image circle to boot\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• dual-speed 2\" rack-and-pinion focuser with 10:1 ratio fine focusing\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 2\" and 1.25\" non-marring compression ring accessory holders\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• rotating camera angle adjuster\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• split mounting rings with Vixen-style dovetail\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• sliding lens shade with lock knob\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• finderscope mounting shoe\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003c\/span\u003e\u003c\/strong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis unique apochromatic ED quad refractor astrograph has a four lens\/two group\/two ED element fully-multicoated optical system. It uses an FPL-53 element in its apochromatic triplet objective lens, and has a separate field-flattening proprietary ED singlet lens at the rear of the optical tube.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe very sensibly-priced Astro-Tech AT65EDQ astrograph provides an exceptionally flat field for very wide DSLR and CCD deep space images that are sharp edge-to-edge, with no need for a separate field flattener. While designed primarily as an astrograph, it can also be used visually with a 1.25\" star diagonal and eyepieces.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTo see an impressive image of the North American Nebula showing the flat field capability of the AT65EDQ, taken by Luke Leege, please look through the images above. The NGC700 image was take by Luke using a Canon EOS 7D DSLR camera. Luke took 12 five minute exposures and 7 ten minute exposures with appropriate darks and flats. He combined them using Deep Sky Stacker freeware and processed the result in Photoshop CS3.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eAnother good example of the AT65EDQ's capability in the hands of an experienced astrophotographer is Jeremy Vandermeer's image of the Rosette Nebula, also found in the images above. It was taken from the light-polluted suburbs of Chicago. Jeremy combined 47 separate 240 second exposures taken with a modified Canon T1i to produce the final image, which we think compares quite favorably with professional images taken with much larger and more expensive scopes. Jeremy said about the AT65EDQ, \"this scope is great.\" So is Jeremy's image.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eCan you take images as good as these with a 65mm scope? At the low price of the AT65EDQ it won't cost you a fortune to try your hand at wide field astrophotography.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eOther manufacturers often use FPL-51 ED glass or its equivalent in their more-expensive triplet designs to keep their manufacturing costs down, or use FPL-53 in a simple doublet. In comparison to this approach, Astro-Tech uses a more-expensive true FPL-53 ED (Extra-low Dispersion glass) element in the triplet objective lens of the modestly-priced AT65EDQ. The result is the finest possible control of spurious color, for images that are free of all vestiges of the annoying faint color halos around bright objects visible in lesser scopes. In addition, a fourth lens of a proprietary ED type acts as a field flattener for wide field imaging.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThose exceptional optics are even more impressive when you consider the package they come in. The finely-machined AT65EDQ has a dual speed 2\" rack-and-pinion focuser with a microfine 10:1 fine-focusing ratio. The standard equipment camera angle adjuster rotates a full 360° for the most pleasing photographic compositions. The supplied 2\" and 1.25\" accessory holders use non-marring brass compression rings that won't scratch your accessory barrels.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eIf this Astro-Tech AT65EDQ was simply a top-quality 65mm FPL-53 ED doublet system, it would be fairly priced. But - a 65mm fast focal ratio quadruplet astrograph using true FPL-53 glass, with a dual-speed 2\" rack and pinion focuser and a built-in ED field flattener at this price . . . is the kind of super value only Astro-Tech can give you!\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFeatures of this Telescope . . .\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eApochromatic quadruplet ED refractor optics:\u003c\/strong\u003e the objective lens is a 65mm (2.56\") aperture, 420mm focal length, f\/6.5 focal ratio triplet using an element of high quality FPL-53 ED (Extra-low Dispersion glass) to reduce spurious color halos and fringing to vanishingly low levels. In addition, there is a separate ED glass singlet lens at the rear of the optical tube that acts as a field flattener to eliminate the curved field typical of fast focal ratio doublet and triplet refractors. Stars are focused and point-like to the edges of the field. This built-in field flattener eliminates the need to buy the separate external field flattener that most refractors need to provide flat field images.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eFully multicoated optics:\u003c\/strong\u003e All lenses have the latest state-of-the-art antireflection multicoatings matched to their glass types on all air-to-glass surfaces for high light transmission and excellent contrast.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eDew shield\u003c\/strong\u003e: A self-storing retractable dew shield slows the formation of dew on the lens in cold weather to extend your undisturbed observing time. It also improves the contrast, similar to the effect of the lens shade on a camera lens, when observing during the day or when there is excessive ambient light at night, such as a neighbor's backyard security light. The 4.75 pound AT65EDQ measures a very compact 13\" long with the dew shield retracted, and is only 14.25\" long with it extended.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eDual speed 2\" rack-and-pinion focuser with 2\" accessory holder and 1.25\" accessory adapter, both with compression rings:\u003c\/strong\u003e The precision-made rack-and-pinion focuser has dual-speed focusing. There are two coarse focusing knobs. The right knob also has a smaller concentric knob with 10:1 reduction gear fine focusing ratio. This provides exceptionally precise image control during critical DSLR or CCD imaging. The focus knobs have ribbed gripping surfaces so they are easy to operate, even while wearing gloves or mittens in cold weather.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe 2\" focuser drawtube terminates in a built-in camera angle adjuster as standard equipment. It is not an optional extra-cost accessory, as it is with some other scopes. The camera angle adjuster lets you rotate the 2\" accessory holder to line up a camera in either a landscape or portrait orientation (or any orientation in between). A knob on the camera angle adjuster lets you lock the focuser at whatever angle provides the most pleasing photographic composition.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe 62mm (2.44\") travel 2\" diameter focuser drawtube has a scale marked in 1mm increments so you can note individual focuser positions for easy return to the approximate correct focus when switching between visual use and photography or when switching between cameras. A lock knob under the focuser lets you lock in your photographic focus. The dual thumbscrew 2\" drawtube has a 2\" accessory holder that uses a non-marring soft brass compression ring to hold 2\" accessories in place. The compression ring won't scratch the barrel of your accessories as an ordinary thumbscrew can.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eA standard equipment 1.25\" accessory adapter slips into the 2\" accessory holder to let you use a 1.25\" star diagonal, image erecting diagonal, or photo accessories. Like the 2\" accessory holder, the 1.25\" adapter also uses a non-marring soft brass compression ring to hold 1.25\" accessories in place. If you are partial to 1.25\" eyepieces and need an outstanding diagonal for this scope, consider the Astro-Tech 1.25\" dielectric diagonal (#AT1D). It's a Sky \u0026amp; Telescope Hot Product for 2007. Most 2\" star diagonals will not reach infinity focus with the AT65EDQ with either 1.25\" or 2\" eyepieces, so a 1.25\" diagonal is recommended for visual use.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eTube finish:\u003c\/strong\u003e The optical tube and lens shade are finished in a durable textured powder coat, the same as that used on scopes three times the price of the AT65EDQ. The focuser and trim are black anodized.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eTube rings and dovetail:\u003c\/strong\u003e The AT65EDQ comes with a pair of felt-lined 80mm hinged split mounting rings with 1\/4\"-20 thread mounting holes in the top and bottom of each ring, plus a Vixen-style dovetail. Supplied mounting bolts let you install the rings on the supplied dovetail or on an optional Losmandy-style \"D-plate\" dovetail for using the AT65EDQ on an equatorial mount. They will also let you attach the rings to optional Vixen- or Losmandy-style dovetail adapters for piggybacking the AT65EDQ on top of a larger scope. A 1\/4\"-20 thread mounting hole in the Vixen-style dovetail will let you mount the AT65EDQ on an optional standard photo tripod for use as a terrestrial spotting scope or telephoto lens.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOther supplied accessories:\u003c\/strong\u003e A slip-on metal dust cap is standard. There is a dovetail shoe on the upper left side of the optical tube for installing an optional multiple reticle red dot finder such as the Astro-Tech #ATF, using a #ATFBV base.\u003c\/span\u003e\u003c\/p\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221669425225,"sku":"AT65EDQ","price":649.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/18437.jpg?v=1662967883"},{"product_id":"astro-tech-6-f-4-imaging-newtonian-optical-tube","title":"Astro-Tech 6\" f\/4 Imaging Newtonian Optical Tube","description":"This new light weight 6\" f\/4 Astro-Tech imaging Newtonian reflector makes serious very wide field astrophotography possible with even a small equatorial mount, and at a lower cost than ever before . . .\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eThis Astro-Tech Imaging Newtonian optical tube has:\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eVery fast f\/4 focal ratio 6\" Newtonian reflector optics\u003c\/strong\u003e\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eContrast-enhancing extended tube length \u003c\/strong\u003e\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003e2\" dual-speed linear bearing Crayford focuser with 2\" and 1.25\" compression ring accessory adapters \u003c\/strong\u003e\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003e8 x 50mm finderscope in a quick-release bracket \u003c\/strong\u003e\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eDual split hinged mounting rings\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis 6\" Astro-Tech AT6IN optical tube is a very fast focal ratio f\/4 reflector that has been optimized for very wide field deep space imaging. It can be used with 35mm cameras, DSLRs, web-cams, DSI-type cameras, and large format CCD cameras alike.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe light weight standard equipment mounting rings of the Astro-Tech Imaging Newtonian allow you to use it on a wide variety of dovetail plates and German equatorial mounts - from the most basic to the most elaborate high payload go-to system.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eIn addition to deep space imaging, the Astro-Tech AT6IN is also usable for solar system imaging as well as deep space and solar system visual observing. Solar system visual contrast will be somewhat reduced compared to a longer focal ratio reflector because of the AT6IN's larger secondary mirror that has been optimized for full-field photographic illumination. However, the visual performance will still be much more than acceptable, and the 610mm focal length of this Astro-Tech makes it quite possible to achieve the high powers needed for detailed lunar and planetary observing. Simply add optional 1.25\" or 2\" eyepieces, and perhaps an optional Barlow lens, and this Astro-Tech Imaging Newtonian will provide you with crisp and sharply detailed close-up views of the Moon and planets.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eThis Astro-Tech Telescope's Optical System . . .\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eNewtonian reflector optics: 6\" aperture, 610mm focal length, f\/4 focal ratio. Parabolic primary mirror. Both primary and diagonal mirrors are ground and polished under computer control for guaranteed diffraction limited performance, coated with 91% reflectivity aluminum, and overcoated with a protective layer of silicon dioxide (quartz) for long life.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe mirrors are made of B270 \"water white\" optical crown glass that is free of internal stress and striae. B270 glass is equivalent to BK7 in performance and optical quality. The thermal stability of B270 glass is generally better than the soda lime float glass used for the mirrors of most reflectors in this reasonable price range. For maximum contrast, the four secondary mirror spider vanes have been optimized to be as thin as possible without losing stability.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eNo-tool push-pull mirror cell:\u003c\/strong\u003e The die-cast aluminum primary mirror cell has six hand adjust push-pull collimation knobs. These make it easy to collimate the primary mirror without tools, even while wearing gloves or mittens in cold weather. To further ease collimation, the primary mirror is center-spotted.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eExtended optical tube:\u003c\/strong\u003e To increase the contrast, the optical tube of the Astro-Tech AT6IN is extended 7.25\" forward of the focuser centerline to act as a lens shade to keep ambient light from hitting the diagonal mirror. This results in higher contrast than a conventional reflector for both imaging and visual observing.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe white-painted 22.5\" long x 7\" diameter Astro-Tech optical tube (with 7.25\" diameter front and rear cells) is fabricated of rolled steel, to allow the mirrors to cool to ambient temperature more quickly. While the rolled steel optical tube is a little heavier than a more-costly aluminum tube, a Sky \u0026amp; Telescope review of the AT6IN's 8\" big brother AT8IN pointed out that a steel tube \"also helps make it a very rigid setup, which is a good thing for astrophotographers.\" The scope's tube end rings are sturdy die-cast aluminum, to protect the tube during transport and provide exceptionally rigid support for the optics. \u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFor essentially coma-free imaging with the AT6IN, consider adding the Astro-Tech ATCC coma corrector. This imaging accessory essentially eliminates the coma inherent in all fast focal ratio reflector telescope designs, so that the coma-free star images remain point-like all across the field.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003e2\" dual-speed linear bearing Crayford focuser:\u003c\/strong\u003e The precision-made 2\" linear bearing Crayford focuser drawtube ends in a 2\" accessory holder. A 1.25\" accessory adapter is standard equipment. Both the drawtube's 2\" accessory holder and the 1.25\" accessory adapter have non-marring compression ring eyepiece\/accessory holders.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe focuser has dual-speed focusing. There are two coarse focusing knobs. The knob facing the rear of the scope also has a smaller concentric knob with a 10:1 reduction gear microfine focusing ratio. This provides exceptionally precise image control during critical imaging. All focus knobs are ribbed, so they are easy to operate, even while wearing gloves or mittens in cold weather. A lock knob underneath the focuser lets you adjust the tension on the drawtube to accommodate varying equipment loads. A large lock knob on top of the focuser lets you lock in your photographic focus. \u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe new linear bearing focuser has a polished stainless steel drive rail that runs the length of the underside of the drawtube. The focuser's stainless steel drive shaft presses on this drive rail to move the focuser, rather than having the hard steel drive shaft press directly on (and wear out) the softer aluminum drawtube as with conventional Crayford focusers. The steel drive rail rides in a self-lubricating track that extends almost the entire length of the focuser body. The drive rail and its attached drawtube are thereby supported over most of their length at all times, rather than by a conventional Crayford focuser's two sets of small contact area roller bearings. This system distributes the drive force evenly over the entire drawtube, without concentrating it on a few small contact points. The result is a very rigid drawtube with essentially zero flexure and no wear (much less flat spots or uneven wear) on the focuser drawtube. \u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe focuser drawtube has 51mm (2\") of travel. A focusing scale on top of the focuser drawtube is marked in inches and millimeters to make it easy to return to the approximate correct focus when setting up to image or observe each night.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eSplit tube rings:\u003c\/strong\u003e A pair of die-cast aluminum hinged split tube mounting rings are provided. Each ring has a flat boss on its underside with a 1\/4\"-20 thread mounting hole, flanked by two 4mm metric holes on 30mm centers, for installing the ring on a Vixen-style or Losmandy-style \"D-plate\" dovetail mounting plate. This lets you mount the scope on virtually any equatorial mount. In addition, there is a flat boss with a 4mm metric hole on the top of each ring. This allows you to install a separate dovetail on top of the optical tube for mounting photoguide rings and a guidescope or similar accessories piggyback on top of the AT6IN. The lightweight optical tube (9 pounds 10 ounces without finderscope) rotates in its felt-lined die cast cradle rings to bring the focuser and finder to the most comfortable viewing position.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eFinderscope:\u003c\/strong\u003e 8 x 50mm straight-through dark crosshair achromatic design, in a spring-loaded quick-release mounting bracket. The finder has a long and comfortable 13mm eye relief. To focus the finder, loosen the trim ring behind the objective lens cell, screw the lens cell in or out to focus, and tighten the trim ring to lock in the correct focus.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch2\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTech Details: \u003c\/span\u003e\u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eAperture\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBinary and Star Cluster Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eVery Good\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e610mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Ratio\u003c\/th\u003e\n\u003ctd class=\"data\"\u003ef\/4\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eGalaxy and Nebula Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eGood\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eHeaviest Single Component\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e9 lbs. 10 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eHighest Useful Magnification\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e203x\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eLunar Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eGreat\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePlanetary Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eVery Good\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eResolution\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e0.76 arc seconds\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eVisual Limiting Magnitude\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e13.4\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cblockquote\u003e\n\u003cul\u003e\n\u003cul\u003e\u003c\/ul\u003e\n\u003c\/ul\u003e\n\u003c\/blockquote\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221670834249,"sku":"AT6IN","price":399.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/18868.jpg?v=1662967926"},{"product_id":"astro-tech-12-medium-yellow-1-25-color-filter","title":"Astro-Tech #12 Medium Yellow 1.25\" Color Filter","description":"\u003cp\u003eThis #12 medium yellow Astro-Tech 1.25\" eyepiece filter is helpful in improving lunar and Martian contrast in telescopes 4\" to 8\" in aperture, particularly if combined with a polarizing or neutral density filter when used with the larger apertures.  Similar in performance to the #8 light yellow filter, but more pronounced effect. Its transmission is somewhat better suited to scopes in the 4\" to 8\" aperture range, while the #8 filter's transmission is better suited to apertures 3.5\" and below.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eRecommended applications for this filter:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMoon -\u003c\/strong\u003e Improves contrast between lunar features of varying brilliance in scopes 4\" and larger, especially when combined with a polarizer or neutral density filter with scopes in the 6\" to 8\" aperture range. \u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eVenus -\u003c\/strong\u003e Occasionally helpful in revealing low-contrast banding in the thick Venusian cloud cover.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMars -\u003c\/strong\u003e Increases the contrast of polar caps, frost areas, low clouds, and dust storms against the ochre deserts. Also sharpens the boundaries of yellow dust clouds.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eJupiter -\u003c\/strong\u003e Somewhat useful for darkening atmospheric currents containing low-hue blue tones and enhancing detail in small orange-red zonal features in the belts. Useful for studies of the polar regions.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSaturn -\u003c\/strong\u003e Somewhat useful for darkening atmospheric currents containing low-hue blue tones and enhancing detail in orange-red zonal features in the belts. Improves the visibility of Cassini's Division in the rings.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eNeptune and Uranus -\u003c\/strong\u003e Somewhat useful for enhancing very subtle dusky features in scopes 10\" and larger.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eComets -\u003c\/strong\u003e Brings out highlights in yellowish comet dust tails and improves the contrast of comet heads.\u003c\/p\u003e\n\u003cp\u003e \u003cstrong\u003e74% transmission\u003c\/strong\u003e\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eColor\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e12 - Medium Yellow\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221671489609,"sku":"ATCF12","price":11.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/19069.jpg?v=1662967939"},{"product_id":"astro-tech-21-orange-1-25-color-filter","title":"Astro-Tech #21 Orange 1.25\" Color Filter","description":"\u003cp\u003eThis #21 orange Astro-Tech 1.25\" eyepiece filter is useful in improving contrast when observing the Moon and all planets out to Saturn in telescopes 6\" to 8\" in aperture and larger, particularly if combined with a polarizing or neutral density filter. \u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eRecommended applications for this filter:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMoon -\u003c\/strong\u003e Very useful for improving contrast between lunar features in scopes 6\" and larger, with or without polarizer or neutral density filter.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMercury -\u003c\/strong\u003e Darkens terrestrial sky during daylight viewing to enhance rarely visible subtle surface albedo differences.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eVenus -\u003c\/strong\u003e Darkens terrestrial sky during daylight viewing to show the phases more clearly.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMars -\u003c\/strong\u003e Increases the contrast of polar caps, frost areas, low clouds, and dust storms against the ochre deserts. Also sharpens the boundaries of yellow dust clouds.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eJupiter -\u003c\/strong\u003e Brings out structure in the belts and enhances festoons and polar regions.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSaturn -\u003c\/strong\u003e Improves the structure of atmospheric bands and highlights blue-toned polar regions.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eComets -\u003c\/strong\u003e Can be piggybacked with #38A filter to improve contrast of orange Sodium D lines in comet gas tails in scopes 10\" and larger. Enhances the definition of comet heads and dust tails in 10\" and larger scopes.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSolar -\u003c\/strong\u003e Used to give correct color rendition of the Sun when using a Mylar solar filter.\u003c\/p\u003e\n\u003cp\u003e \u003cstrong\u003e46% transmission\u003cbr\u003e\u003cbr\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eColor\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e21 - Orange\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e2 years\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221671555145,"sku":"ATCF21","price":11.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/19071.jpg?v=1662967941"},{"product_id":"astro-tech-23a-light-red-1-25-color-filter","title":"Astro-Tech #23A Light Red 1.25\" Color Filter","description":"\u003cp\u003eThis #23A light red Astro-Tech 1.25\" eyepiece filter is useful when observing Mercury and Venus during the day and at twilight and when observing Mars, Jupiter, and Saturn with telescopes 4\" in aperture and larger.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eRecommended applications for this filter:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMoon -\u003c\/strong\u003e Somewhat useful for improving contrast between lunar features in scopes 8\" and larger.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMercury -\u003c\/strong\u003e Improves observations at twilight, when the planet is near the horizon. Reduces brightness of terrestrial sky to enhance daylight observing.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eVenus -\u003c\/strong\u003e Reduces brightness of terrestrial sky in daylight observing, allowing occasional terminator deformations to be seen.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMars -\u003c\/strong\u003e Filters out scattered blue light in the Martian atmosphere to Increase the contrast and definition of polar caps, frost areas, low clouds, and dust storms against the ochre deserts, particularly when Mars is close to Earth's horizon, as the red light it passes is the least refracted by air currents in our atmosphere. Reduces light from blue and green areas which darkens the maria, oases, and canal markings, while lightening the orange-hued desert regions. Sharpens the boundaries of yellow dust clouds.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eJupiter -\u003c\/strong\u003e Brings out structure in the belts and enhances festoons and polar regions.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSaturn -\u003c\/strong\u003e Useful on Saturn for studying the bluer cloud bands and polar regions.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eComets -\u003c\/strong\u003e Enhances the definition of comet dust tails in 10\" and larger scopes. \u003cbr\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e25% transmission\u003c\/strong\u003e\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eColor\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e23A - Light Red\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221671587913,"sku":"ATCF23","price":11.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/19072.jpg?v=1662967942"},{"product_id":"astro-tech-29-dark-red-1-25-color-filter","title":"Astro-Tech #29 Dark Red 1.25\" Color Filter","description":"\u003cp\u003eIf you have a big scope (10\" in aperture and larger), this #29 dark red Astro-Tech 1.25\" eyepiece filter can be useful when observing Mercury and Venus during the day and at twilight and when observing Mars, Jupiter, and Saturn.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eRecommended applications for this filter:\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMoon -\u003c\/strong\u003e Somewhat useful for improving contrast between lunar features in scopes 10\" and larger.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMercury -\u003c\/strong\u003e Improves observations at twilight, when the planet is near the horizon. Reduces brightness of terrestrial sky to enhance daylight observing.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eVenus -\u003c\/strong\u003e Reduces brightness of terrestrial sky in daylight observing, allowing occasional terminator deformations to be seen.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMars -\u003c\/strong\u003e Very useful for Increasing the contrast and definition of polar caps, frost areas, and maria against the ochre deserts with scopes 8\" and larger, particularly when Mars is close to Earth's horizon, as the red light it passes is the least refracted by air currents in our atmosphere. Sharpens the boundaries of yellow dust clouds.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eJupiter -\u003c\/strong\u003e Very useful in defining blue-tinted cloud formations against lighter-toned atmospheric features.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSaturn -\u003c\/strong\u003e Very useful in defining blue-tinted cloud formations and polar regions against the lighter-toned planetary disc.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eComets -\u003c\/strong\u003e Enhances the definition of comet dust tails in 12\" and larger scopes. \u003cbr\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e6% transmission\u003c\/strong\u003e\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eColor\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e29 - Dark Red\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221671653449,"sku":"ATCF29","price":11.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/19074.jpg?v=1662967944"},{"product_id":"astro-tech-47-violet-1-25-color-filter","title":"Astro-Tech #47 Violet 1.25\" Color Filter","description":"\u003cp\u003eIf you have a big scope (8\" in aperture and larger), this Astro-Tech #47 violet 1.25\" eyepiece filter can help detect high clouds and haze over the Martian polar caps and enhance structure in Saturn's rings with telescopes 8\" to 10\" in aperture and larger.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eRecommended applications for this filter:\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMercury -\u003c\/strong\u003e May improve observations of rarely visible faint surface features with scopes 8\" to 10\" in aperture and larger.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eVenus -\u003c\/strong\u003e Increases contrast of occasional faint dark shadings in the upper cloud deck.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMars -\u003c\/strong\u003e Useful for detecting high clouds and haze over the polar caps with large scopes, particularly during the still-unexplained phenomenon of violet clearing (when the Martian atmosphere - normally a bright, featureless disc in violet light due to the scattering of short wavelengths of light by the thin atmosphere - becomes transparent through a violet or blue filter, revealing large dark surface features).\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eJupiter -\u003c\/strong\u003e Primarily used for enhancing the boundaries between the reddish belts and adjacent bright zones in the upper atmosphere . Helpful in defining the Great Red Spot and festoons in the belts with scopes 8\" and larger.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSaturn -\u003c\/strong\u003e Good for enhancing the ring structure with 8\" or larger scopes.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eComets -\u003c\/strong\u003e Useful for observing brighter comets with scopes 10\" and larger. \u003cbr\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e3% transmission\u003c\/strong\u003e\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eColor\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e47 - Violet\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221671751753,"sku":"ATCF47","price":11.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/19076.jpg?v=1662967947"},{"product_id":"astro-tech-56-light-green-1-25-color-filter","title":"Astro-Tech #56 Light Green 1.25\" Color Filter","description":"\u003cp\u003eIf you have a scope 6\" in aperture and under, this Astro-Tech #56 light green 1.25\" eyepiece filter is a useful tool for observing different features on every planet from Venus to Saturn  with telescopes from 60mm to 150mm (6\") in aperture.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eRecommended applications for this filter:\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMoon -\u003c\/strong\u003e Useful for enhancing the contrast of lunar features in scopes 6\" and smaller.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eVenus -\u003c\/strong\u003e Useful for Venusian cloud pattern studies and to reduce the brightness of the terrestrial sky during daylight observing of Venus (an excellent time to observe this planet, as the high contrast of Venus against the dark night sky often makes for uncomfortable and unsatisfactory observing, while during the day the contrast range is not nearly as great, irradiation within your eye is reduced, and subtle Venusian features are sometimes more visible).\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMars -\u003c\/strong\u003e Excellent for increasing contrast of Martian polar caps and surface frosts with scopes 6\" and smaller.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eJupiter -\u003c\/strong\u003e Increases the visibility of the Great Red Spot (which is more like a Faint Red Spot at the present time) with scopes 6\" and smaller. Useful for observing the low-contrast hues of red and blue visible in the Jovian atmosphere. Enhances white features in the planetary atmosphere.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSaturn -\u003c\/strong\u003e Enhances white features in the planetary atmosphere. \u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e53% transmission\u003c\/strong\u003e\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eColor\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e56 - Light Green\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221671784521,"sku":"ATCF56","price":11.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/19077.jpg?v=1662967949"},{"product_id":"astro-tech-58-dark-green-1-25-color-filter","title":"Astro-Tech #58 Dark Green 1.25\" Color Filter","description":"\u003cp\u003eThis Astro-Tech #58 dark green 1.25\" eyepiece filter is very helpful when observing the Moon and Mars, plus enhances a variety of features on all the other planets from Venus to Saturn If you have a scope 8\" in aperture and larger.\u003cstrong\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cdiv\u003e\u003cstrong\u003eRecommended applications for this filter:\u003c\/strong\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eMoon -\u003c\/strong\u003e Excellent for enhancing the contrast of lunar features in scopes 8\" and larger. \u003cstrong\u003e\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eVenus -\u003c\/strong\u003e Increases contrast of occasionally-visible Venusian cloud patterns. Reduces the brightness of the terrestrial sky during daylight observing of Venus (an excellent time to observe this planet, as the high contrast of Venus against the dark night sky often makes for uncomfortable and unsatisfactory observing, while during the day the contrast range is not nearly as great, irradiation within your eye is reduced, and subtle Venusian features are sometimes more visible).\u003c\/div\u003e\n\u003cdiv\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eMars -\u003c\/strong\u003e Excellent for increasing contrast of Martian polar caps and surface frosts with scopes 8\" and larger. Sharpens low-lying clouds.\u003c\/div\u003e\n\u003cdiv\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eJupiter -\u003c\/strong\u003e Increases the visibility of the Great Red Spot (which is more like a Faint Red Spot at the present time) with scopes 8\" and larger. Useful for observing the low-contrast hues of red and blue visible in the Jovian atmosphere. Enhances white features in the planetary atmosphere.\u003c\/div\u003e\n\u003cdiv\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eSaturn -\u003c\/strong\u003e Enhances white cloud belts and polar regions.\u003c\/div\u003e\n\u003cdiv\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eComets -\u003c\/strong\u003e Useful for observing brighter comets with scopes 8\" and larger. \u003cbr\u003e\u003cstrong\u003e\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cstrong\u003e24% transmission\u003c\/strong\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/div\u003e\n\u003cdiv\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eColor\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e58 - Dark Green\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221671817289,"sku":"ATCF58","price":11.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/19078.jpg?v=1662967950"},{"product_id":"astro-tech-4mm-1-25-value-line-plossl","title":"Astro-Tech 4mm 1.25\" Value Line Plössl Eyepiece","description":"\u003cp\u003e\u003cspan style=\"color: rgb(255, 42, 0);\"\u003e\u003cstrong\u003eThis product has been discontinued and is here for informational purposes only.\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003eThis 4mm Astro-Tech Value Line is one of the shortest focal length and most economically-priced Plössl eyepieces available. It's designed for very high magnification lunar and planetary observing and for splitting close binary stars . . .This 4mm Astro-Tech fully-multicoated Value Line Plössl is one of the shortest focal length and most economically-priced Plössl eyepieces available. It's designed for very high magnification lunar and planetary observing and for splitting close binary stars. Short eye relief will vignette the field of view for eyeglass wearers, so we can't recommend this eyepiece for those who \u003cem\u003emust\u003c\/em\u003e wear glasses while observing. However, vignetting of the edges of the field shouldn't be an issue when observing small objects, such as planets, and when splitting binary stars.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eBarrel Size\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eEye Relief\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eField of view\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e52\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e4mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eNumber of optical elements\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e4\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e2.6 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221671882825,"sku":"ATPL04","price":17.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/19081.jpg?v=1662967952"},{"product_id":"astro-tech-2x-achromatic-barlow-for-1-25-eyepieces","title":"Astro-Tech 2X Achromatic Barlow for 1.25\" Eyepieces","description":"\u003cp\u003eThis physically short (3.1\") Astro-Tech 2x achromatic Barlow is an inexpensive way to cleanly double the power of any 1.25\" eyepiece in your collection . . .The Astro-Tech AT2XB achromatic 2x Barlow is physically quite short at 3.1\" in length. This allows it to be used in the star diagonal of catadioptric and refractor telescopes to keep the eyepiece height comfortably low, as well as being used in reflector focusers. \u003c\/p\u003e\n\u003cp\u003eBy doubling the power of each eyepiece it is used with, this Astro-Tech Barlow effectively doubles the number of 1.25\" eyepieces in your collection. It uses a two-element, fully-multicoated optical system for excellent color correction and sharpness and works best at focal ratios of f\/6 and above. The lens edges are blackened for maximum image contrast. The body is made of precision CNC-machined aluminum and is anodized for long life. A thumbscrew holds eyepieces in place.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eBarrel Size\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eLength\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e3.1\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eNumber of optical elements\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePower\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e2x\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e3.3 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40221671915593,"sku":"AT2XB","price":29.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/19090.jpg?v=1662967953"},{"product_id":"astro-tech-6-f-9-ritchey-chretien-astrograph","title":"Astro-Tech 6\" f\/9 Ritchey-Chrétien Astrograph","description":"The exceptional value 6\" Astro-Tech Ritchey-Chrétien astrograph is once again available for the serious deep space astrophotographer on a budget . .\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eThis Astro-Tech AT6RC Ritchey-Chrétien astrograph has:\u003c\/strong\u003e\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003e• 6\" f\/9 true Ritchey-Chrétien hyperbolic mirror optical design\u003c\/strong\u003e\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003e• diffraction-limited or better BK-7 mirrors\u003c\/strong\u003e\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003e• enhanced aluminum optical coatings, overcoated with quartz\u003c\/strong\u003e\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003e• dual-speed 2\" Crayford focuser\u003c\/strong\u003e\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003e• 1\" and 2\" extension rings for fine-tuning the back focus\u003c\/strong\u003e\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003e• Vixen-style dovetail rail\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eDeveloped and introduced by Astro-Tech - and named a Sky \u0026amp; Tel Hot Product for 2009 - the Astro-Tech 6\" AT6RC Ritchey-Chrétien astrograph is back by popular demand!\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe Ritchey-Chrétien optical design is used in virtually every recent large mega-million dollar professional observatory telescope - including the Hubble Space Telescope. And more \"affordable\" true coma-free Ritchey-Chrétiens made for schools and individuals, with prices starting in the thousands of dollars, typically come only in large apertures whose weights require a large and expensive mount to use successfully.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eIn contrast, the Astro-Tech AT6RC is an incredibly affordable Ritchey-Chrétien astrograph (a telescope designed specifically for photographing comparatively wide areas of the sky) that virtually all astronomers can afford! At only 12.9 pounds, it can be used successfully with a wide variety of affordable equatorial mounts or piggybacked on an existing scope - no ultra-expensive astrophotography mount required.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe AT6RC is designed for coma-free imaging using webcams, Deep Sky Imager-type cameras, and DSLRs. The December 2009 issue of Sky \u0026amp; Telescope said the Astro-Tech AT6RC is \"a superb match\" for the APS-C chips used in many DSLR cameras, \"yielding a field almost 1° wide with very good star images in all but the corners of the frame.\" It is not designed for digiscoping through an eyepiece. Featuring a true Ritchey-Chrétien optical system, this very economical 6\" Astro-Tech R-C makes you wonder just what those multi-thousand dollar R-Cs have that makes them cost so much.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe M104, Sombrero Galaxy, photo above is from Bill Bradford. He sent it to us simply with the comment, \"Here is another shot with the AT6RC. Sure liking the scope.\" This image was named an astrophotography \"Picture of the Day\" on the Astronomy magazine website in July 2009.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe AT6RC lunar photo above is from an AT6RC owner, John O'Neill. It was taken with an Olympus Evolt 300 DSLR camera at 1\/200 of a second through a polarizing filter. John commented, \"I took this last full moon with the 6\" RC. I'm very impressed with this scope. I had to collimate it a bit but after doing that the images I am getting are just superb. You certainly have a winner with this scope, at any price point.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\"This may very well be the ideal scope for DSLR users,\" John continued. \"Its fast focal ratio and wide field of view is ideal for many astro targets. I did take some shots of some deep sky objects from my light polluted neighborhood and found that the star field was pin point to the edges of my 35mm camera.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe first light image of M81 and M82 above was made by Matthew Reiche using a modified Canon XSI, an Astro-Tech AT2F field flattener, and an Orion Atlas mount. It consists of 32 five minute exposures, plus darks, flats, and bias frames, for a total exposure of 2.5 hours. It was recorded at the Jenny Jump State Park in New Jersey. Matthew said, \"This was first light with my AT6RC and I think it's going to be a great scope.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eDesigned for exceptional imaging with DSLRs and DSI-type cameras, the Astro-Tech AT6RC provides the wide coma-free photographic field that astrophotographers crave, but can't get from conventional reflectors and Schmidt-Cassegrains. Likewise, as a pure two-mirror system, the AT6RC is totally free from the spurious color that affects the imaging of all but the most costly apochromatic refractors, and it does it with an 6\" aperture that equals or exceeds the light gathering of most apo refractors.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe compact size and light weight of the AT6RC, and built-in Vixen-style dovetail, makes it easy for you to mount the ascope on any mid-range equatorial mount by itself or piggyback it on your existing larger scope for imaging. An optional second Vixen-style dovetail (#AT6SDP) is available for mounting on top of the AT6RC body. This allows you to piggyback accessories (such as a photoguide scope) on top of the AT6RC if the scope is installed directly on your equatorial mount.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eIf serious astrophotography is your goal, but the price of most true Ritchey-Chrétien optics has been keeping you from the optical design most modern professional observatories and the Hubble Space Telescope use for their imaging, your wait is over. The Astro-Tech AT6RC can bring the world of professional deep space imaging to your backyard observatory at a truly affordable price.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eFeatures of this Astro-Tech AT6RC Astrograph . . .\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptical design:\u003c\/strong\u003e true Ritchey-Chrétien two-mirror Cassegrain optics, with hyperbolic primary and secondary mirrors. 6\" aperture, 1370mm focal length, f\/9 focal ratio.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid primary mirror:\u003c\/strong\u003e Made of BK-7 optical glass. Polished to diffraction-limited or better surface accuracy. Unlike catadioptric designs (SCTs, Maksutovs, etc.) that move the primary mirror to focus (which can lead to image shift as the mirror moves), the AT6RC mirror is fixed to eliminate potential image shift. The fixed primary mirror also eliminates the frequent primary mirror collimation requirements of a Newtonian reflector.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe December 2009 issue of Sky \u0026amp; Telescope said that the AT6RC fixed primary and secondary mirrors \"eliminate image shift, which has been the bane of Cassegrain scopes with moving-mirror focusing systems . . . It also keeps the effective focal length of the system constant, and the infinity focal point remains at a fixed point outside of the telescope, neither of which is the case with moving-mirror systems that change the separation between a Cassegrain's primary and secondary mirrors.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid secondary mirror:\u003c\/strong\u003e Made of BK-7 optical glass. Polished to diffraction-limited or better surface accuracy. Mounted in a four-vane spider and fully collimatable.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eEnhanced aluminum optical coatings:\u003c\/strong\u003e Both primary and secondary mirrors have enhanced aluminum mirror coatings, overcoated with a protective layer of quartz for long life. Reflectivity is in the 96% range, the same as the larger multi-thousand dollar R-C scopes.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptical tube:\u003c\/strong\u003e Painted rolled steel, 7.5\" o.d. x 19.25\" long, with die-cast and machined aluminum front and rear cells.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eInternal light baffles:\u003c\/strong\u003e Computer optimized primary and secondary baffling. Eight contrast-enhancing glare-stop baffles in the optical tube, multiple glare-stop microbaffles in the secondary mirror light shield, and four baffles in the primary mirror baffle tube provide truly dark sky backgrounds during imaging.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eDual-speed Crayford focuser:\u003c\/strong\u003e A 2\" Crayford focuser is threaded onto the 90mm x 1mm pitch rear cell of the AT6RC. The non-vignetting focuser has dual-speed focusing. There are two coarse focusing knobs. The right knob also has a smaller concentric knob with a 10:1 reduction gear microfine focusing ratio. This provides exceptionally precise image control during critical CCD imaging. All focus knobs are ribbed, so they are easy to operate, even while wearing gloves or mittens in cold weather.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eFocuser travel:\u003c\/strong\u003e Focuser drawtube travel is 34mm, while back focus between the focuser's 2\" accessory holder and the focal plane is 150mm. The December 2009 issue of Sky \u0026amp; Telescope said that \"the infinity focus of the AT6RC falls 9-3\/4\" outside the back of the telescope, allowing plenty of room for all types of cameras, filter wheels, and ancillary equipment.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTwo extension rings (one 1\" and one 2\") are provided to thread onto the rear of the scope (singly or in combination) between the scope rear cell and the focuser. These form a very rigid and tilt-free extension that moves the focuser out from the rear cell to accommodate the varying back-focus requirements of webcam\/Deep Sky Imager-type cameras versus DSLRs. Typically, both rings (one 1\" and one 2\") will properly position most DSLRs at the AT6RC focal plane. Sky \u0026amp; Telescope pointed out that the \"1- and 2-inch extensions, as well as conventional extension tubes that fit in the 2-inch focuser, mean that you can always assemble the system so it comes to focus with whatever camera and accessories you're using.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eWhile it is possible to use large CCD cameras and filter wheels with the AT6RC, these cameras are generally not recommended. The weight of a standard CCD camera and the color filter wheel typically used with it may cause the focuser drawtube to tilt slightly when fully extended, affecting the focus. Adding an optional Feather Touch focuser (our part #FT-1.5BC), plus an optional 90mm x 1mm pitch adapter (our part #M90X1), will eliminate any such potential problem, although at significant additional cost (more than double the cost of the AT6RC itself).\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFor even more impressive coma-free DSLR imaging with the AT6RC, consider adding the Astro-Tech AT2FF field flattener. This modestly-priced imaging accessory essentially eliminates the residual field curvature inherent in all reflector telescope designs, so that the coma-free star images remain point-like all across the field of the APS-C size imaging chip used in most DSLR cameras. Use of the #AT2FF with a DSLR will typically requires one optional #AT2EXT 2\" extension ring, instead of the two rings generally needed with a DSLR camera alone.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eCompression ring accessory holders:\u003c\/strong\u003e The focuser drawtube ends in a 2\" accessory holder that uses a non-marring soft brass compression ring to hold 2\" imaging accessories in place. The compression ring won't scratch the barrel of your accessories as an ordinary thumbscrew can. Also supplied is a 1.25\" accessory holder that slips into the 2\" compression ring holder to let you use 1.25\" imaging accessories. Like the 2\" eyepiece holder on the eyepiece holder rotation mechanism, the 1.25\" adapter also uses a non-marring soft brass compression ring.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eMounting dovetail:\u003c\/strong\u003e a Vixen-style dovetail bar runs the length of the underside of the optical tube. The dovetail can be removed, if desired, so the AT6RC can be installed in optional user-supplied mounting rings for piggyback mounting on a larger scope. An optional #AT6SDP Vixen-style dovetail is available for mounting on top of the AT6RC to allow you to mount an optional photoguide scope on top of the astrograph.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eFinderscope dovetail:\u003c\/strong\u003e a Vixen-style finderscope bracket dovetail base is installed on the upper left side of the optical tube. It can easily be removed if not needed. It will accept Vixen-style finderscope brackets as well as red dot-type finders, such as the Astro-Tech #ATF.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOther accessories:\u003c\/strong\u003e A snap-in dust cap is standard.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch2\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTech Details: \u003c\/span\u003e\u003c\/h2\u003e\n\u003ctable style=\"max-width: 500px;\" id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eAperture\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1370mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eFocal Ratio\u003c\/th\u003e\n\u003ctd class=\"data\"\u003ef\/9\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e12.9 lbs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eResolution\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e0.76 arc seconds\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eTelescope Type\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eRitchey-Chrétien\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eBack Focus\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e150mm with focuser installed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch2\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eSupplied Accessories: \u003c\/span\u003e\u003c\/h2\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong style=\"color: #21201c; font-family: tahoma, verdana, sans-serif; font-size: 16px; line-height: 27px; background-color: #ffffff;\"\u003e• 1\" and 2\" extension rings for fine-tuning the back focus\u003cbr\u003e• Vixen-style dovetail rail\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cdiv id=\"product_tabs_additional_contents\" class=\"product-tabs-content\"\u003e\n\u003cdiv class=\"product-tabs-content-inner clearfix\"\u003e\n\u003cdiv class=\"box-add clearfix\"\u003e\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481972551753,"sku":"AT6RC","price":479.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/19910.jpg?v=1675378871"},{"product_id":"1-25-99-reflectivity-dielectric-quartz-mirror-diagonal-neaf-demo","title":"Astro-Tech 1.25\" 99% Reflectivity Dielectric Quartz Mirror Diagonal","description":"\u003cp\u003e\u003cspan style=\"color: #ff0000;\"\u003e\u003cstrong\u003eTHIS PRODUCT HAS BEEN DISCONTINUED.  THIS PAGE IS HERE FOR INFORMATIONAL PURPOSES ONLY.\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\r\n\u003cp\u003eIn addition to 99% reflectivity \u003cem\u003edielectric \u003c\/em\u003ecoatings, this Astro-Tech 1.25\" star diagonal has a premium first-surface mirror made of low thermal expansion quartz, rather than conventional BK7 glass . . .\u003c\/p\u003e\u003cp\u003e\u003cspan style=\"color: #ff0000;\"\u003e\u003cstrong\u003eTHIS PRODUCT HAS BEEN DISCONTINUED.  THIS PAGE IS HERE FOR INFORMATIONAL PURPOSES ONLY.\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\r\n\u003cp\u003eThis 1.25\" Astro-Tech star diagonal is quartz mirror upgrade to the original (and still available) Astro-Tech diagonal named a \u003cem\u003eSky \u0026amp; Telescope Hot Product for 2007. \u003c\/em\u003eLike the original, the AT1DQ uses high transmission\/high contrast dielectric mirror coatings, but substitutes a low thermal expansion quartz mirror for the original's BK7 optical glass mirror. This premium-quality diagonal brings all the optical benefits of a 2\" quartz diagona to scopes that can only use 1.25\" accessories.\u003c\/p\u003e\r\n\u003cp\u003eThe Astro-Tech AT1DQ diagonal has state-of-the-art \u003cem\u003e46-layer \u003c\/em\u003edielectric mirror coatings for a full 99% reflectivity. This is markedly higher reflectivity than the 88% of a conventional aluminum diagonal or the 96-97% of an easily-tarnished silver diagonal. The result? Extremely faint objects at your scope's performance limits become more visible, changing your viewing from \"I guess I see it\" to \"it's really there!\"\u003c\/p\u003e\r\n\u003cp\u003eIn addition, the durable ion-deposited dielectric coatings on the mirror's finely-polished 1\/10th wave quartz substrate have an exceptionally smooth surface. Since less light is scattered by the smooth dielectric surface than by the minor 1\/20th wave to 1\/200th wave surface irregularities of an aluminized mirror, you see subtly higher contrast and resolution with the Astro-Tech during critical planetary, lunar, and binary star observations.\u003c\/p\u003e\r\n\u003cp\u003eThe quartz mirror substrate has low thermal expansion characteristics, so you don't have to worry about focus change issues as your diagonal and scope acclimate to the nighttime temperature.\u003c\/p\u003e\r\n\u003cp\u003eThe mirror housing is precision-machined from solid aluminum, rather than simply flimsy Bakelite plastic or a sheet metal stamping, as you'll find with ordinary diagonals. A rigid machined metal backplate with stainless steel hardware holds the mirror in perfect optical alignment in the machined body. The interior of the body is anodized an antireflective matte black. The focuser-side barrel is also anodized antireflective matte black, and is internally antireflection threaded for even higher contrast. The barrel is threaded to accept standard 1.25\" filters.\u003c\/p\u003e\r\n\u003cp\u003eThe 1.25\" eyepiece holder uses a non-marring soft brass compression ring to clamp eyepieces in place, rather than a thumbscrew that can scratch an eyepiece barrel by tightening down on it directly.\u003c\/p\u003e\r\n\u003cp\u003eA shallow slanted groove cut into the outside of the focuser-side barrel engages with the scope's visual back or eyepiece holder thumbscrew to act as a safety stop. This keeps the diagonal from falling should the scope's thumbscrew loosen slightly from cold or use. Dust covers are provided for both sides of the diagonal.\u003c\/p\u003e\r\n\u003cp\u003eThis premium 1.25\" diagonal works with virtually any Schmidt-Cassegrain, Maksutov-Cassegrain, or refractor that uses a 1.25\" star diagonal,. It will provide a visible improvement over the scope's factory-supplied diagonal. The newly designed body of the Astro-Tech diagonal is more compact than previous diagonals. This essentially eliminates any possibility of the diagonal bumping into the drive base of a short fork arm catadioptric when the scope is pointed at the zenith. This Astro-Tech quartz mirror diagonal gives you all the visual performance your scope is capable of delivering, at a price that's very affordable.\u003c\/p\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481972912201,"sku":"AT1DQ","price":119.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/19964.jpg?v=1675378892"},{"product_id":"astro-tech-at60edt-60mm-f-7-ed-triplet-apo-refractor-white-and-gray-tube","title":"Astro-Tech At60Edt 60Mm F\/7 Ed Triplet Apo Refractor, White And Gray Tube","description":"\u003cp\u003e\u003cspan style=\"color: #ff0000;\"\u003e\u003cstrong\u003eTHIS PRODUCT HAS BEEN DISCONTINUED.  THIS PAGE IS HERE FOR INFORMATIONAL PURPOSES ONLY.\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\r\n\u003cp\u003eThe Astro-Tech AT60EDT is a very compact\/very high quality apochromatic triplet refractor that is equally at home observing visually or doing serious wide field imaging . . . \u003c\/p\u003e\u003cp\u003e\u003cspan style=\"color: #ff0000;\"\u003e\u003cstrong\u003e\u003cstrong\u003eTHIS PRODUCT HAS BEEN DISCONTINUED.  THIS PAGE IS HERE FOR INFORMATIONAL PURPOSES ONLY.\u003c\/strong\u003e\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\r\n\u003cp\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/p\u003e\r\n\u003cp\u003e\u003cstrong\u003eThis Astro-Tech AT60EDT ED triplet refractor has:\u003cbr\u003e\u003cbr\u003e• 60mm f\/7 fully multicoated apochromatic ED triplet refractor optics\u003cbr\u003e• dual-speed rotating 2\" rack-and-pinion focuser with 10:1 ratio fine focusing\u003cbr\u003e• 2\" and 1.25\" non-marring compression ring accessory holders\u003cbr\u003e• combined dovetail\/tripod bracket for use on a photo tripod or a German equatorial mount\u003cbr\u003e• retractable self-storing lens shade\u003cbr\u003e• amazing wide field astrophotographic capabilities\u003cbr\u003e• long-lasting white and gray paint finish\u003cbr\u003e• aluminum-frame foam-fitted hard case\u003cbr\u003e• two-year warranty\u003c\/strong\u003e\u003cbr\u003e\u003cbr\u003eThe Astro-Tech AT60EDT is a superb grab-and-go visual scope, a fine wide-field astrograph, and a daytime spotting scope. Its 420mm f\/7 ED air-spaced apochromatic triplet optics are essentially free from spurious color (chromatic aberration), even at high magnifications. The optical performance - both visually and photographically - is little short of astonishing. \u003cbr\u003e\u003cbr\u003eThe exceptional AT60EDT triplet optics are even more impressive when you consider the package they come in. The substantial (5.3 pounds) and finely-machined scope has a dual speed 2\" rack-and-pinion focuser with a microfine 10:1 fine-focusing ratio. You can rotate the focuser a full 360° to put your eyepiece or camera in the most comfortable observing position. The supplied 2\" and 1.25\" eyepiece adapters use non-marring brass compression rings that won't scratch your eyepiece and accessory barrels. The Astro-Tech AT60EDT has a retractable lens shade and comes in a locking aluminum-frame hard carrying case.\u003cbr\u003e\u003cbr\u003eThis 11\" long refractor optical tube (14\" long with the lens shade extended) has the right balance of aperture and focal length to use as a low-power rich field telescope, as a medium-power planetary telescope, or as any kind of telescope in between. Its compact size and convenient removable L-shaped mounting foot that mounts on any photographic tripod also make it an excellent terrestrial spotting scope for vacations, birding, or nature studies. In addition, optional camera adapters turn the AT60EDT into a superb 420mm (8.4x with a 35mm camera or a large chip DSLR) f\/7 daytime telephoto lens and nighttime wide-field astrograph. The photo tripod mounting foot is also a Vixen-style dovetail that mounts directly on many altazimuth and German equatorial mounts, such as those from Astro-Tech, Celestron, Meade, and Vixen.\u003cbr\u003e\u003cbr\u003e\u003cbr\u003e\u003cstrong\u003eFeatures of this Astro-Tech refractor. . .\u003c\/strong\u003e\u003cbr\u003e\u003cbr\u003e\u003cstrong\u003eED triplet refractor optics:\u003c\/strong\u003e 60mm (2.36\") aperture, 420mm focal length, f\/7 focal ratio air-spaced triplet lens using premium Ohara glass from Japan, including an ED (Extra-low Dispersion glass) element to reduce spurious color halos and fringing to apochromatic levels. \u003cbr\u003e\u003cbr\u003e\u003cstrong\u003eMulticoated optics:\u003c\/strong\u003e The objective lens has the latest state-of-the-art broadband antireflection multicoatings on all air-to-glass surfaces for high light transmission and excellent contrast. This can easily be seen by looking into the objective lens of the scope. Virtually no reflection of your face will be seen, even in brightly lit situations. It's a sure sign that the high transmission coatings are doing their job, by letting virtually all the light enter the scope, rather than reflecting some light back to your eye.\u003cbr\u003e\u003cbr\u003e\u003cstrong\u003eAnti-reflection treatment:\u003c\/strong\u003e The interior of the optical tube uses special matte black paint and anti-reflection threading the full length of the focuser drawtube for truly dark sky backgrounds and high daytime terrestrial contrast. In addition, the edges of the objective lens are blackened to eliminate contrast-reducing stray internal reflections.\u003cbr\u003e\u003cbr\u003e\u003cstrong\u003eFull power range capability:\u003c\/strong\u003e The \"highest useful magnification\" is theoretically 140x. This is the power obtained with a 3mm eyepiece, which provides an exit pupil of 0.43mm (less than 1\/50th of an inch) and 59x per inch of aperture. This is generally the smallest exit pupil recommended with any telescope before the images start to become too dim to be consistently useful.\u003cbr\u003eHigher powers are possible for lunar and planetary observing, however, given excellent seeing conditions, although the increasing dimness of the image will start to limit the performance on all but the brightest objects.\u003cbr\u003eThe lowest useful power is 10.5x, achieved with a 40mm eyepiece (a 40mm 1.25\" TeleVue Plössl will give you a 4.1° field at that power; while a 2\" Explore Scientific 40mm 68° Series will give you a 6.48° field). At 4.4x per inch of aperture, this is very close to the 4x per inch of aperture generally regarded as the lowest practical power with any telescope. A 40mm eyepiece on the AT60EDT will give you a 5.7mm exit pupil, about the maximum to which most eyes can dilate. Any lower power would simply waste some of the scope's light gathering capacity, as some of its exit pupil, and some of the scope's collected light, would fall on your iris, rather than entering your eye.\u003cbr\u003e\u003cbr\u003e\u003cstrong\u003eDew shield:\u003c\/strong\u003e A self-storing retractable dew shield slows the formation of dew on the lens in cold weather to extend your undisturbed observing time. It also improves the contrast, similar to the effect of the lens shade on a camera lens, when observing during the day or when there is excessive ambient light at night, such as a neighbor's backyard security light.\u003cbr\u003e\u003cbr\u003e\u003cstrong\u003eDual speed microfine 2\" rack-and-pinion focuser with 1.25\" adapter:\u003c\/strong\u003e The precision-made 2\" focuser has dual-speed focusing. There are two coarse focusing knobs. The right knob also has a smaller concentric knob with 10:1 ratio reduction gear microfine focusing. This provides exceptionally precise image control during high power visual observing or critical DSLR or CCD imaging. The focus knobs have knurled rubber and ribbed gripping surfaces so they are easy to operate, even while wearing gloves or mittens in cold weather. \u003cbr\u003eThe drawtube has a very long 95mm (3.75\") travel for imaging, with a scale marked in 1mm increments so you can note individual focuser positions for easy return to the correct focus when switching between visual use and photography. A large knurled lock knob under the focuser lets you solidly lock in your photographic focus.\u003cbr\u003eThe new heavy-duty patent-pending focuser has a precisely-machined 20mm brass rack with a unique slot machined down the center of the rack. When the lock knob on the focuser drawtube is tightened, a slotted shaft on the knob engages the lip of the slot in the rack. This provides a solid metal-to-metal grip on the rack (not merely added friction) to provide an absolute lock of the photographic focus. There is no possibility of focuser slippage once the lock knob is tightened firmly, no matter what the weight of the photo accessories.    \u003cbr\u003eThe focuser drawtube terminates in a 2\" compression ring accessory holder to accept a 2\" star diagonal or 2\" photo accessories. A lock knob on the top of the scope allows the focuser to be rotated a full 360°. This lets you rotate the focuser to line up a camera in either a landscape or portrait orientation (or any orientation in between), as well as put a star diagonal and eyepiece into the most comfortable observing position, and then temporarily lock the focuser in that position.\u003cbr\u003eThe supplied 1.25\" accessory adapter slips onto the 2\" accessory holder and uses a soft brass compression ring to hold 1.25\" star diagonals and photo\/visual accessories in place. The 1.25\" and 2\" compression rings won't scratch the barrels of your star diagonal or accessories as an ordinary thumbscrew can.\u003cbr\u003e\u003cbr\u003e\u003cstrong\u003eCombined equatorial dovetail\/tripod adapter:\u003c\/strong\u003e The AT60EDT has a removable L-shaped dovetail mounting foot\/tripod adapter. The 1.75\" wide x 3.25\" long mounting foot is sized and shaped (with slanted sides) to fit the Vixen-style dovetail slot on the head of many altazimuth and equatorial mounts. It will fit, without modification, the Astro-Tech Voyager altazimuth mount and the Celestron CG-5 and Advanced Series, Meade LXD-75, and Vixen Great Polaris German equatorial mounts, among others.\u003cbr\u003eIn addition, the mounting shoe has a 1\/4\"-20 thread mounting hole that allows it to be installed on any camera tripod that has a standard 1\/4\"-20 thread mounting bolt. \u003cbr\u003eCork pads on the underside of the mounting shoe help keep the scope from swiveling when mounted on a photo tripod. The dovetail is removable to allow the 75mm diameter optical tube AT60EDT to be used with optional guidescope rings as a photoguide for a larger telescope.\u003cbr\u003e\u003cbr\u003e\u003cstrong\u003eTube finish:\u003c\/strong\u003e The optical tube is finished in a durable and subtly-textured white automotive-grade paint with black trim and a gray and black focuser.\u003cbr\u003e\u003cbr\u003e\u003cstrong\u003eOther supplied accessories:\u003c\/strong\u003e A slip-on metal dust cap is standard. Two threaded holes for installing a finderscope mounting bracket are located on the upper side of the rotating focuser so you can install a finder on either the right or left side, as you prefer. \u003cbr\u003e\u003cbr\u003e\u003cstrong\u003eShipping\/storage case:\u003c\/strong\u003e The scope comes in a 15.5\" x 10\" x 7.5\" aluminum-frame locking hard case with carry handle. The foam-fitted case has cutouts for the scope, a 1.25\" or 2\" star diagonal, and up to three eyepieces (two 1.25\" and one 2\").\u003cbr\u003eAstro-Tech is one of the very few manufacturers to provide a case at no charge for protection during shipping and as a storage convenience when the scope is not in use. Unfortunately, FedEx, UPS, and the Postal Service are very good at treating packages roughly. Occasionally, your scope can arrive in perfect condition, but with the walls of the shipping case dented in transit from rough handling, or the aluminum frame sprung, rendering the appearance of the case less than pristine. Damage to the shipping\/storage case in such instances is not covered by warranty.\u003cbr\u003e\u003cbr\u003e\u003cstrong\u003eTwo year warranty:\u003c\/strong\u003e As an expression of the confidence Astronomy Technologies has in the quality of their products, the Astro-Tech AT60EDT is protected by a two-year limited warranty against flaws in materials and workmanship (shipping case excluded).\u003c\/p\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481973338185,"sku":"AT60EDT","price":599.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/20001.jpg?v=1675378921"},{"product_id":"astro-tech-0-8x-reducer-field-flattener-for-f-6-refractors","title":"Astro-Tech 0.8X Reducer\/Field Flattener For f\/6 Refractors","description":"This economical Astro-Tech 2\" 0.8x reducer\/field flattener is designed for astrophotography with f\/6 focal ratio refractors, but will also work well with refractors in the f\/5.5 to f\/7 range . . . \u003cbr\u003e\n\u003cp\u003eNew for August 2021, thread on adapter tops to choose between 42mm T-threads and 48mm T-threads.\u003c\/p\u003e\n\u003cp\u003eWhile this Astro-Tech #ATR8 0.8X reducer\/field flattener is designed for prime focus astrophotography with quality f\/6 focal ratio apo refractors such as the Astro-Tech AT72ED and AT130 apo, it will also work well with Astro-Tech and other brand refractors in the f\/5.5 to f\/7 range that use a 2\" focuser.\u003cbr\u003e\u003cbr\u003eFor example, the fully-multicoated Astro-Tech ATR8 converts the 430mm focal length f\/6 Astro-Tech AT72ED refractor into a 344mm f\/4.8 lens for faster and wider field astronomical and terrestrial photography, while the 777mm f\/7 Astro-Tech AT111EDT converts into a 622mm f\/5.6. \u003cbr\u003e\u003cbr\u003eIn addition to reducing the focal length of the telescope and thereby increasing the photographic speed, the ATR8 flattens the normal field curvature inherent in all refractors to provide images that are sharply focused out to the very corners of a large format DSLR chip. Stars look sharp and point-like all the way across the field in your images. You don't have to worry about photos that are sharp in the center and blurry at the edges.\u003cbr\u003e\u003cbr\u003eThe Astro-Tech ATR8 reducer\/flattener fits 2\" focusers. The 2\" telescope-side barrel is threaded for standard 2\" filters and has a beveled safety groove. The camera side of the reducer has an adapter choice beteen 42mm T-threads, or 48mm T-threads, to connect to a T-ring and camera body. A thread-on metal cover protects the T-threads when the reducer is not in use, while a slip-on dust cover is provided for the 2\" scope-side barrel. Back focus is 55mm from the shoulder of the reducer to the image plane, the standard spacing for 35mm and DSLR camera bodies. The image circle at the focal plane is 42mm in diameter. \u003cbr\u003e\u003cbr\u003e\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"max-width: 500px;\" id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e5.6 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481973370953,"sku":"ATR8","price":149.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/20002.jpg?v=1675378924"},{"product_id":"astro-tech-8-f-8-ritchey-chretien-astrograph-steel-tube","title":"Astro-Tech 8\" f\/8 Ritchey-Chrétien Astrograph, Steel Tube","description":"The steel tube Astro-Tech AT8RC makes premium 8\" Ritchey-Chrétien optics for serious deep space imaging available at the lowest price ever. \u003cem\u003eSky \u0026amp; Telescope\u003c\/em\u003e named the AT8RC a \u003cem\u003eSky \u0026amp; Telescope Hot Product for 2010.\u003c\/em\u003e A review in the December 2009 Sky \u0026amp; Telescope said \"it was how nicely this scope is matched to APS-C and 35mm formats that really wowed me.\"\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis Astro-Tech AT8RCS Ritchey-Chrétien astrograph has:\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 8\" f\/8 true Ritchey-Chrétien hyperbolic mirror optical design\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• low thermal expansion quartz primary and secondary mirrors\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 96% reflectivity enhanced aluminum mirror coatings\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• ten contrast-enhancing main tube knife edge light baffles \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• dual-speed linear Crayford focuser\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• 2\" and 1.25\" compression ring accessory holders \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e• two dovetail rails - one Vixen-style and one Losmandy-style \"D-plate\"\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe original carbon fiber tube AT8RC that Astro-Tech helped develop was the first sensibly-priced 8\" true Ritchey-Chrétien astrograph with premium features available from a U. S. company. Sky \u0026amp; Telescope magazine named it a Hot Product for 2010, along with its larger 10\" brother, the AT10RC.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eAs Sky \u0026amp; Telescope pointed out in their Hot Product citation, \"Ritchey-Chrétien reflectors are highly regarded among today's elite astrophotographers, and premium instruments often carry price tags starting at about $1,000 per inch of aperture. So it's the best kind of 'sticker shock' to see the prices for Astro-Tech's 8- and 10-inch f\/8 Ritchey-Chrétiens.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eBe prepared for more \"sticker shock,' as the new steel tube AT8RCS is even more affordable than the original carbon fiber version.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe Astro-Tech AT8RCS astrograph (a telescope designed specifically for photographing comparatively wide areas of the sky) makes the coma-free imaging of true Ritchey-Chrétien imaging optics available to the DSLR and CCD astrophotographer at a price less than that of most CCD cameras. It is not designed for digiscoping through an eyepiece. Featuring premium low thermal expansion quartz mirrors rather than ordinary optical glass, this very economical 8\" Astro-Tech R-C makes you wonder just what those outrageously expensive R-Cs have that makes them cost so much.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eDesigned for exceptional imaging, the Astro-Tech AT8RCS provides the wide coma-free photographic field that DSLR and CCD astrophotographers crave, but can't get from conventional reflectors and Schmidt-Cassegrains. Likewise, as a pure two-mirror system, the AT8RCS is totally free from the spurious color that affects the imaging of all but the most costly apochromatic refractors, and it does it with an 8\" aperture that dwarfs the light gathering of most apo refractors.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eIf serious astrophotography is your goal, but the price of most true Ritchey-Chrétien optics has been keeping you from the optical design most modern professional observatories and the Hubble Space Telescope use for their imaging, your wait is over. The Astro-Tech AT8RCS astrograph can bring the world of professional DSLR\/CCD deep space imaging to your backyard observatory at a remarkably affordable price.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFeatures of this Astro-Tech AT8RCS astrograph . . .\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptical design:\u003c\/strong\u003e true Ritchey-Chrétien Cassegrain-type two-mirror optics, with hyperbolic primary and secondary mirrors. \u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eOptical specifications: 8\" aperture, 1625mm focal length, f\/8 focal ratio.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid primary mirror:\u003c\/strong\u003e Made of low thermal expansion quartz, rather than the ordinary optical glass used by competitors. Ground and polished under precision computer control to diffraction-limited or better surface accuracy. Unlike catadioptric designs (SCTs, Maksutovs, etc.) that move the primary mirror fore and aft in the optical tube to focus (which can lead to image shift as the mirror position changes) the AT8RCS primary mirror is fixed to eliminate both a catadioptric's image shift and the primary mirror collimation requirements of a Newtonian reflector.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid secondary mirror:\u003c\/strong\u003e Made of low thermal expansion quartz, rather than ordinary optical glass. Ground and polished under precision computer control to diffraction-limited or better surface accuracy. Mounted in a four-vane spider and fully collimatable using simple standard Cassegrain reflector collimating techniques. Unlike complicated R-C designs that use motors to move the secondary mirror fore and aft to focus, the AT8RCS secondary mirror is fixed and focusing is done externally.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003e96% reflectivity enhanced aluminum coated optics:\u003c\/strong\u003e Both primary and secondary mirrors are coated with 96% reflectivity enhanced aluminum, overcoated with a layer of quartz for long life.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eSteel optical tube:\u003c\/strong\u003e While not quite as resistant to temperature-related focus changes as its more expensive carbon fiber brother, the 9\" o.d. x 18\" long steel tube of the AT8RCS will require few, if any, focus adjustments during most imaging sessions.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eMultiple internal light baffles:\u003c\/strong\u003e Computer optimized primary and secondary baffling. Ten contrast-enhancing glare-stop baffles in the optical tube; multiple glare-stop microbaffles in the secondary mirror light shield; and five baffles in the primary mirror baffle tube provide truly dark sky backgrounds during imaging.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eDual-speed linear Crayford focuser:\u003c\/strong\u003e A new design 2\" Crayford focuser is threaded onto the 90mm x 1mm pitch rear cell of the AT8RCS. The matte black interior of the new longer 50mm travel drawtube has anti-reflection threading for high contrast. The focuser can be rotated to any convenient angle for the sake of photographic composition by simply loosening the collar that secures the focuser to the scope body, rotating the focuser to the desired angle, and tightening the collar to lock the focuser in the new orientation.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe new bearing-less linear focuser has a polished stainless steel drive rail that runs the length of the drawtube, rather than having the stainless steel drive shaft simply press directly on (and wear) the aluminum drawtube as with conventional Crayford focusers. The drive rail rides in a self-lubricating track that extends most of the length of the focuser body. The drive rail and its attached drawtube are thereby supported over most of their length at all times, rather than by a conventional Crayford focuser's two sets of small contact area roller bearings. This system distributes the drive force evenly over the entire drawtube, without concentrating it on a few small contact points. The result is less potential drawtube flexure and no wear (much less uneven wear) on the drawtube.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe precision-made non-vignetting focuser has dual-speed focusing. There are two coarse focusing knobs. The right knob also has a smaller concentric knob with a 10:1 reduction gear microfine focusing ratio. This provides exceptionally precise image control during critical imaging. All focus knobs are ribbed, so they are easy to operate, even while wearing gloves or mittens in cold weather. Multiple internal baffles in the focuser drawtube assure high contrast.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eDespite the new more rigid focuser design, the weight of very heavy equipment trains (camera, plus filter wheel, plus temperature-compensated electric focuser, etc.) may cause the 50mm long focuser drawtube to tilt slightly when fully extended, affecting the focus. Three threaded extension rings (two 1\" in length and one 2\") are provided to install singly or in combination between the AT8RCS rear cell and the focuser. These provide a flex-free solid metal extension that changes the distance between the focuser and the rear cell. This lets you accommodate the varying back-focus requirements of DSLR-type camera imaging versus long equipment train CCD imaging, while minimizing the need to extend the focuser drawtube. Additional optional 1\" and 2\" long threaded extension rings are available to fine-tune the back focus as needed, as well as optional Astro-Tech 2\" compression ring extension tubes that fit into the focuser drawtube.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThe image plane is located 10\" behind the rear cell. With the standard dual-speed Crayford focuser installed on the scope, there is 159.71mm of back focus available from the top surface of the 2\" accessory holder to the image plane.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFor exceptionally long and heavy imaging equipment trains, the standard Crayford focuser can be user-replaced by an optional 1.5\" travel Feather Touch focuser from Starlight Instruments, #FT-1.5BC. This requires a 90mm x 1mm pitch rear cell thread to Feather Touch adapter, #M90X1. Optional MoonLite focusers from MoonLite Telescope Accessories can also be used.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFor even more impressive coma-free imaging with the AT8RCS, consider adding the Astro-Tech AT2FF field flattener. While not specifically designed to work with Ritchey-Chrétien astrographs, images taken with the field flattener by Astro-Tech R-C owners have shown that the Astro-Tech 2\" field flattener works remarkably well with these advanced coma-free reflectors as well as with refractors. This modestly-priced imaging accessory essentially eliminates the residual field curvature inherent in all reflector telescope designs, so that the coma-free star images remain point-like all across the field. An optical analysis and ray tracing of the field flattener was done in ZEMAX and applied to the R-Cs by Roger Ceragioli, the noted optical designer who did the final optimization of the Astro-Tech Ritchey-Chrétien optics. Here is what he had to say about the #AT2FF, \"My conclusion, which seems supported by what users are saying, is that you don't need any other field flattener. This one performs well over a 40mm image circle in all three small RCs (6\", 8\", and 10\").\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eTwo compression ring accessory holders:\u003c\/strong\u003e The focuser drawtube ends in a 2\" accessory holder that uses a non-marring soft brass compression ring to hold 2\" imaging accessories in place. The compression ring won't scratch the barrel of your accessories as an ordinary thumbscrew can. Also supplied is a 1.25\" accessory holder that slips into the 2\" compression ring holder to let you use 1.25\" imaging accessories. Like the 2\" accessory holder on the drawtube, the 1.25\" adapter also uses a non-marring soft brass compression ring.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eTwo dovetail mounting rails:\u003c\/strong\u003e Two dovetail rails are provided for installing the AT8RS on an equatorial mount, as well as for mounting optional accessories (such as a photoguide scope) on top of the AT8RCS. One is a Losmandy-style \"D-plate\" dovetail rail that runs the full length of the underside of the optical tube, for installing the AT8RCS on a Losmandy-style equatorial mount. The second is a Vixen-style dovetail rail that runs the full length of the top of the tube. This can be used for installing a photoguide ring set, piggyback camera adapter, or any other accessory that attaches to a scope by means of Vixen-style dovetail adapters. If the AT8RCS is rotated 180°, it will bring the Vixen-style rail to the bottom of the tube so it can be used to install the AT8RCS on a Vixen-style equatorial mount. Competitors provide only one Vixen-style dovetail. Providing two dovetail rails on the Astro-Tech AT8RCS does not limit your choice of mounts or accessory mounting options, as can happen with similar scopes provided with only one mounting rail.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eFinderscope dovetail:\u003c\/strong\u003e a Vixen-style finderscope bracket dovetail base is installed on the upper left side of the optical tube. It can easily be removed if not needed. It will accept Vixen-style finderscope brackets as well as red dot-type finders, such as the Astro-Tech #ATF.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOther accessories:\u003c\/strong\u003e A snap-in dust cap is standard.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch2\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTech Details: \u003c\/span\u003e\u003c\/h2\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\" style=\"max-width: 500px;\" data-mce-style=\"max-width: 500px;\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\" data-mce-style=\"width: 25%;\"\u003eAperture\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e8\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\" data-mce-style=\"width: 25%;\"\u003eBinary and Star Cluster Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\" data-mce-style=\"width: 25%;\"\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1625mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\" data-mce-style=\"width: 25%;\"\u003eFocal Ratio\u003c\/th\u003e\n\u003ctd class=\"data\"\u003ef\/8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\" data-mce-style=\"width: 25%;\"\u003eGalaxy and Nebula Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\" data-mce-style=\"width: 25%;\"\u003eLunar Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\" data-mce-style=\"width: 25%;\"\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e18.9 lbs.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\" data-mce-style=\"width: 25%;\"\u003ePlanetary Observation\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\" data-mce-style=\"width: 25%;\"\u003eResolution\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e0.57 arc seconds\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\" data-mce-style=\"width: 25%;\"\u003eTelescope Type\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eRitchey-Chrétien\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\" data-mce-style=\"width: 25%;\"\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\" data-mce-style=\"width: 25%;\"\u003eBack Focus\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e10 (254mm) from rear cell, 6.25 (159mm) with standard focuser installed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003ch2\u003eSupplied Accessories:\u003c\/h2\u003e\n\u003cp\u003e• 2\" and 1.25\" compression ring accessory holders \u003cbr\u003e• two dovetail rails - one Vixen-style \u003cem\u003eand \u003c\/em\u003eone Losmandy-style \"D-plate\"\u003c\/p\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481974419529,"sku":"AT8RCS","price":1199.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/20071.jpg?v=1675378977"},{"product_id":"astro-tech-16-f-8-truss-tube-ritchey-chretien-optical-tube","title":"Astro-Tech 16\" f\/8 Truss Tube Ritchey-Chrétien Optical Tube","description":"This newest version of the Astro-Tech AT16RCT carbon fiber Serrurier truss 16\" f\/8 Ritchey-Chrétien \u003cstrong\u003e\u003cem\u003e\u003cspan style=\"color: #990000;\"\u003eHot Product for 2015\u003c\/span\u003e\u003c\/em\u003e\u003c\/strong\u003e makes high quality large-aperture DSLR and CCD imaging affordable for the dedicated amateur astrophotographer and educational institution.\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis newest Version A of the Astro-Tech AT16RCT Ritchey-Chrétien astrograph (named a Sky \u0026amp; Telescope Hot Product for 2015) has:\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e16\" f\/8 true Ritchey-Chrétien hyperbolic mirror optical design\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003ecarbon fiber Serrurier truss tube design with CNC-machined stainless steel and aluminum components\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e18-point primary mirror floatation system\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003elow thermal expansion quartz primary and secondary mirrors \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003ethree built-in cooling fans in rear cell \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e3\" dual-speed compression ring Crayford focuser with 2\" and 1.25\" adapters \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003efocuser attachment collar isolated from the primary mirror and baffle tube\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003edust covers and finder shoe\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e \u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis newest version of the Astro-Tech AT16RCT makes 16\" coma-free true Ritchey-Chrétien imaging available to the DSLR and large format CCD astrophotographer at a price less than that of some large format CCD cameras by themselves. \u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e Featuring first-quality premium low thermal expansion quartz mirrors, rather than aluminized Pyrex glass mirrors, this reasonably-priced 16\" Astro-Tech truss-tube R-C provides the coma-free photographic field that large format CCD and DSLR astrophotographers crave, but can't get from conventional reflectors and Schmidt-Cassegrains.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e Likewise, as a pure two-mirror system, the AT16RCT has a wide spectral response and is totally free from the spurious color that affects the imaging of all but the most costly apochromatic refractors, and it does it with a 16\" aperture that dwarfs the light gathering of every commercially-available apo refractor.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e If serious astrophotography is your goal, but the price of true Ritchey-Chrétien optics has been keeping you from the optical design most modern professional observatories use, your wait is over. The 16\" Astro-Tech AT16RCT truss-tube R-C can bring the world of professional DSLR\/CCD deep space imaging to your backyard observatory at a truly affordable price.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFor cropped sections of some astrophotos taken with the AT16RCT, courtesy of Steve Cooper, look at the feature images above. To see Steve's original full-size and uncropped Eagle Nebula image, with full details on exposure times and camera used, click on this link: \u003ca href=\"http:\/\/www.pbase.com\/ccoop\/image\/161543902\" target=\"_blank\"\u003ehttp:\/\/www.pbase.com\/ccoop\/image\/161543902\u003c\/a\u003e. To see Steve's original image of M51, also with full details on exposure times and camera used, click on this link: \u003ca href=\"http:\/\/www.pbase.com\/ccoop\/image\/161445872\" target=\"_blank\"\u003ehttp:\/\/www.pbase.com\/ccoop\/image\/161445872\u003c\/a\u003e. To see Steve's original image of NGC3718 and 3729, also with full details on exposure times and camera used, click on this link: \u003ca href=\"http:\/\/www.pbase.com\/ccoop\/image\/162653259\" target=\"_blank\"\u003ehttp:\/\/www.pbase.com\/ccoop\/image\/162653259\u003c\/a\u003e.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFeatures of this Astro-Tech AT16RCT Ritchey-Chrétien . . .\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptical design:\u003c\/strong\u003e true Ritchey-Chrétien Cassegrain-type two-mirror optics, with hyperbolic primary and secondary mirrors. The 288mm usable back focus (from the end of the focuser attachment port) allows for the use of long CCD equipment trains.\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eOptical specifications: 16\" aperture, 3250mm focal length, f\/8 focal ratio. Multiple Zygo interferometer tests, during every stage of optics manufacturing (after rough figure generation, after fine figure generation, after final polish before coating, and after dielectric coating), assure premium optical performance.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid primary mirror:\u003c\/strong\u003e Made of low thermal expansion quartz. Ground and polished under precision computer control. Unlike catadioptric designs (SCTs, Maksutovs, etc.) that move the primary mirror fore and aft in the optical tube to focus (which can lead to image shift and a changing focal length and focal ratio as the mirror position changes) the AT16RCT's non-moving primary mirror is supported by an 18-point floatation system. Primary mirror collimation is pre-set at the factory, but can be adjusted if needed using three heavy-duty spring-loaded push\/pull locking adjustment screw sets.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid secondary mirror:\u003c\/strong\u003e Made of low thermal expansion quartz, rather than Pyrex. Ground and polished under precision computer control. Mounted in a CNC-machined four-vane spider and fully collimatable using standard Cassegrain reflector collimating techniques. The secondary mirror is precisely center-spotted to make collimation easier.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e Unlike complicated R-C designs that use motors to move the secondary mirror fore and aft to focus, the AT16RCT secondary mirror is fixed and focusing is done externally by means of an optional external focuser, discussed in the focuser section below. \u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e Sky \u0026amp; Telescope said that the Astro-Tech R-C's fixed primary and secondary mirrors \"eliminate image shift, which has been the bane of Cassegrain scopes with moving-mirror focusing systems . . . It also keeps the effective focal length of the system constant, and the infinity focal point remains at a fixed point outside of the telescope, neither of which is the case with moving-mirror systems that change the separation between a Cassegrain's primary and secondary mirrors.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The secondary mirror's baffle obstruction is 7.44\" (189mm) in diameter (46.5% by diameter and 21.62% by area of the 16\" primary.)\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eCarbon fiber truss-tube design:\u003c\/strong\u003e Four CNC-machined aluminum support rings form the basic structure of the optical tube. Light-weight and rigid carbon fiber tubes connect the support rings in a Serrurier truss design, using CNC-machined stainless steel ball and socket hardware. The middle and rear support rings have a hexagonal outer shape, measuring 22.5\" (572mm) across at their widest point. They are 10mm thick. The dual front support rings provide attachment points for the secondary mirror spider vanes, as well as for the truss tubes. They measure 19.75\" (502mm) across at their widest point of their hexagonal outer shape and are 5mm thick. The AT16RCT measures only 45.5\" long (1156mm) from the front support ring to the end of the focuser mounting collar, and weighs only 77 pounds (35kg) without focuser.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The Serrurier truss solves the problem of optical tube flexure by supporting the primary and secondary mirrors with two sets of opposing trusses mounted before and after the center support ring. The trusses are designed to have an equal amount of flexure, which allows the optics to stay on a common optical axis. When flexing, the \"top\" truss resists tension and the \"bottom\" truss resists compression. This has the effect of keeping the optical elements parallel to each other. The net result is that the optical elements stay in collimation regardless of the orientation of the telescope, including when passing through the meridian during imaging.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The truss tubes are made of a light weight\/high strength woven carbon fiber-reinforced composite material with extremely low thermal expansion characteristics. This reduces the possibility of temperature-related focus changes that can occur with steel or aluminum optical tube scopes during extreme temperature swings.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The Astro-Tech AT16RCT is 45.5\" (1156mm) long without focuser. The supplied focuser adds 5.25\" (133mm) with the drawtube retracted. The center and rear truss tube support rings are 22.5\" (572mm) in diameter, while the front support ring is 19.75\" (502mm) in diameter. The AT16RCT weighs 77 lbs (35 kg) without focuser. The supplied focuser adds 2.2 lbs (1 kg).\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003e3\" Crayford focuser:\u003c\/strong\u003e The AT16RCT is supplied with a basic light duty 3\" Crayford focuser to get you started imaging. While acceptable for casual imaging with a light imaging train (such as a light DSLR body by itself), upgrading to a high quality rack-and-pinion focuser is required for serious imaging with an optical tube of this quality. A heavy multi-component imaging train will require a rack-and-pinion focuser to support the extra weight without focus shift. Alternatively, you may already have a premium focuser being used on another scope that you would like to use for imaging.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The supplied light-duty Crayford focuser can be unthreaded from the focuser attachment collar, allowing you to use another focuser. One popular choice is the dual-speed 3\" diameter 1.5\" travel Feather Touch #3015 rack and pinion focuser, available from your Astro-Tech dealer.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The newly designed focuser attachment collar is bolted to the back plate of the AT16RCT, completely independent of the primary mirror and baffle tube. This allows it to be collimated separately from the primary and secondary mirrors if needed, using the built-in focuser collimating ring. The focuser attachment collar has a male 117m x 1mm pitch thread for attaching the focuser. The Feather Touch #3015 normally comes with a 109mm threaded collar for connecting to a scope. Using the #3015 with the AT16RCT therefore requires an optional #M117x1 Feather Touch adapter. The #M117x1 adapter threads onto the focuser attachment port. The #3015 focuser (without its 109mm collar) then slips into the #M117x1 adapter and is held in place by three large brass Delrin-tipped retaining knobs. Only focusers with a maximum 1.5\" drawtube travel, such as the Feather Touch #3015, are recommended for use with the 16\" Astro-Tech AT16RCT Ritchey-Chrétien. For other focusers, such as a MoonLite, contact the focuser manufacturer for an adapter to fit the 117mm x 1mm port on the rear of the scope.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eBack focus:\u003c\/strong\u003e To fine-tune the 288mm usable back focus of the AT16RCT to the requirements of your camera and equipment train, three threaded extension rings (one 2\" and two 1\" in length) are provided to thread singly or in combination between the focuser attachment collar and the focuser of your choice. These rings provide a flex-free solid metal extension that changes the distance between your chosen focuser and the rear cell. This lets you accommodate the varying back-focus requirements of DSLR-type camera imaging versus long equipment train CCD imaging. The 2\" threaded ring weighs 14.4 ounces, the 1\" rings weigh 7.2 ounces each.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eMount requirements:\u003c\/strong\u003e Because of the 77 pound (35 kg) weight of the AT16RCT, plus the weight of your focuser, ancillary camera equipment, and any photoguide scope, installing the AT16RCT on a German equatorial mount with a 90 to 100 pound minimum payload capacity (preferably greater) is recommended. Such mounts include the Losmandy 100 pound capacity Losmandy HGM Titan; the 220 pound capacity Astro-Physics 1600GTO; and the 90 pound Software Bisque Paramount MX or 240 pound capacity Paramount ME II. Other suitable mounts are also available.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eCooling fans:\u003c\/strong\u003e To allow the AT16RCT to reach ambient temperatures more quickly for optimum imaging performance, there are three low vibration\/high CFM primary mirror cooling fans built into the AT16RCT's rear support truss\/back plate. The high speed DC fans are powered by a standard equipment battery pack that plugs into a 5mm female jack in the back plate. The battery pack uses eight user-supplied AA batteries. An optional external DC power supply, such as a rechargeable 12VDC battery pack can also be used to power the fans.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eTwo dovetail mounting rails:\u003c\/strong\u003e Two 16.2\" (412mm) Losmandy-style \"D-plate\" dovetail rails are bolted to the top and bottom of the center and rear truss-tube support rings. These allow you to install the AT16RCT directly on an equatorial mount and mount optional accessories (such as rings for a photoguide scope) that attach to a scope by means of Losmandy-style \"D-plate\" dovetail adapters. The undersides of the dovetails have been hollowed out to lighten their weight without compromising their strength.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOther accessories:\u003c\/strong\u003e This new version of the AT16RCT includes slip-on dust covers for both the primary and secondary mirrors. Also included is a mounting shoe for a red dot-type finder, such as the Astro-Tech ATF. The mounting shoe can also accept the Astro-Tech ATF50QRB 50mm finderscope quick release bracket.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch2\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTech Details: \u003c\/span\u003e\u003c\/h2\u003e\n\u003ctable style=\"max-width: 500px;\" id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eAperture\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e16\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e3250mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eFocal Ratio\u003c\/th\u003e\n\u003ctd class=\"data\"\u003ef\/8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e77 lbs.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eResolution\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e0.29 arc seconds\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eTelescope Type\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eRitchey-Chrétien\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eVisual Limiting Magnitude\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e15.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eBack Focus\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e11.33\" (288mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481974616137,"sku":"AT16RCT","price":7295.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/20090.jpg?v=1675378989"},{"product_id":"astro-tech-10mm-t-thread-spacer-ring-for-dslr-and-ccd-imaging-with-42mm-threads","title":"Astro-Tech 10mm T-Thread Spacer Ring For DSLR And CCD Imaging With 42mm Threads","description":"\u003cp\u003eThis Astro-Tech 10mm T-thread spacer ring can help provide the necessary spacing between a DSLR or CCD camera's focal plane and a reducer, field flattener, or other imaging accessory in prime focus astrophotography.\u003c\/p\u003e\n\u003cp\u003eThis Astro-Tech 10mm T-thread spacer ring has standard male and female T-threads (42mm x 0.75mm). It is used in prime focus astrophotography to position a DSLR or CCD camera's focal plane the correct distance from a focal reducer, field flattener, or other imaging accessory for optimum image quality. The spacer weighs only 0.5 ounces and is precision-machined from aluminum and anodized black for good looks and durability. It has matte black internal anti-reflection threads for maximum contrast. It can be used alone or in combination with other spacers to achieve the correct component spacing.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"max-width: 500px;\" id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e0.5 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481975566409,"sku":"AT4210","price":9.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/img_2308.jpg?v=1675379039"},{"product_id":"astro-tech-5mm-t-thread-spacer-ring-for-dslr-and-ccd-imaging-with-42mm-threads","title":"Astro-Tech 5mm T-Thread Spacer Ring For DSLR And CCD Imaging With 42mm Threads","description":"\u003cp\u003eThis Astro-Tech 5mm T-thread spacer ring can help provide the necessary spacing between a DSLR or CCD camera's focal plane and a reducer, field flattener, or other imaging accessory in prime focus astrophotography.\u003c\/p\u003e\n\u003cp\u003eThis Astro-Tech 5mm T-thread spacer ring has standard male and female T-threads (42mm x 0.75mm). It is used in prime focus astrophotography to position a DSLR or CCD camera's focal plane the correct distance from a focal reducer, field flattener, or other imaging accessory for optimum image quality. The spacer weighs only one ounce and is precision-machined from aluminum and anodized black for good looks and durability. It has matte black internal anti-reflection threads for maximum contrast. It can be used alone or in combination with other spacers to achieve the correct component spacing.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"max-width: 500px;\" id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481975599177,"sku":"AT4205","price":9.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/img_2307.jpg?v=1675379042"},{"product_id":"astro-tech-1-25-prime-focus-variable-eyepiece-projection-adapter-needs-t-ring","title":"Astro-Tech 1.25\" Prime Focus\/Variable Eyepiece Projection Adapter, Needs T-Ring","description":"\u003cp\u003eThe Astro-Tech Variable Camera Adapter consists of three parts for both prime focus and eyepiece projection imaging with 1.25\" focuser refractors and reflectors. It is generally not used with Schmidt-Cassegrain or Maksutov-Cassegrain telescopes, as these telescopes have their own thread-on adapters. \u003c\/p\u003e\n\u003cdiv\u003eThe 1.25\" barrel prime focus section of the Astro-Tech adapter is used by itself (or with an optional T-ring) for prime focus lunar, and terrestrial photography. The one-piece prime focus section is made of CNC-machined aluminum, anodized matte black, with matte black internal anti-reflection threads. Its one-piece construction assures that the 1.25\" barrel cannot become unscrewed from the T-thread portion, as can happen with two-part chrome barrel adapters. The prime focus section weighs eight-tenths of an ounce.  \u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eThe prime focus section and two-part eyepiece projection section of the Astro-Tech adapter are screwed together for high magnification eyepiece projection photography (using the same optional T-ring). \u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eThe eyepiece projection section consists of two nested tubes, weighing a total of 6.4 ounces. Each section is made of CNC-machined aluminum, anodized matte black, with matte black internal anti-reflection threads. The outer tube (with male T-threads on one end, to which the CCD camera or optional T-ring attaches) can be shortened or lengthened to change the projection distance from 90mm to 125mm. The telescoping outer tube is held firmly at the desired projection distance by two thumbscrews. \u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eA separate thumbscrew holds an eyepiece firmly within the inner tube to project the image from the telescope back to the camera focal plane. The variable projection distance design allows you to change the magnification to vary the size of the image by 44% without the need to change to a different focal length eyepiece. \u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eEyepieces with rubber eyecups may not fit into the camera adapter without temporarily removing the eyecup. The maximum eyepiece o.d. that will fit into the adapter is 36mm (1 and 3\/8\"). The Astro-Tech Variable Camera Adapter needs an optional T-ring for use with 35mm and DSLR cameras. The 1.25\" prime focus section is threaded for 1.25\" filters. The calculator below is set for a 90mm projection distance.\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\" style=\"max-width: 500px;\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eMax Projection Distance\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e125mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eProjection Distance\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e90mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e7.2 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481975631945,"sku":"ATVCA","price":44.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/20136.jpg?v=1675379044"},{"product_id":"astro-tech-1-25-2-laser-collimator","title":"Astro-Tech 1.25\"\/2\" Laser Collimator","description":"\u003cdiv\u003e\n\u003cdiv\u003eThis economical Astro-Tech Laser Collimator permits fast and consistent collimation of a Newtonian reflector's optics, including Dobsonians and astrographs. It works well on telescopes with fast focal ratios of f\/5 or lower, where accurate collimation is especially critical for the best images. Its viewing port has a rear-facing bull's-eye target that lets you adjust your telescope's primary mirror while conveniently standing at the rear of the telescope, where the primary mirror adjustment screws are located.\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eOptics that are out of collimation (with optical elements that are not all exactly aligned on the same optical axis) cannot produce good images. Stars will be elongated or lopsided, planetary details will be hazy and low in contrast, and binary stars will be difficult to split cleanly. Regular collimation with this Astro-Tech Laser Collimator will make sure that you get the best possible image contrast and resolution every night you go out to observe. \u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eTo collimate your secondary mirror, first confirm that your secondary is properly centered under your focuser (either by eye or with an optional sight tube). Adjust the mirror to center it under the focuser if needed, following the procedure in your telescope's instruction manual. Once the secondary is centered, insert the laser into the focuser and observe where the laser beam's red dot lands on your primary mirror when you look at the primary from the front of your optical tube. (If your scope is badly out of collimation, be sure the laser beam is not exiting the front of the scope before looking down the tube.) Most primary mirrors will have a factory-installed center spot or glued-on center donut to help you locate the center of the primary mirror. Simply adjust the secondary mirror's collimation screws as needed until the laser's red dot lands on the center spot or the hole in the middle of the primary's center donut and your secondary will be properly aligned with your primary.\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eNext, move to the rear of the telescope, where the primary mirror is located, and observe where the laser beam's red spot falls on the white bull's-eye in the viewing port of the collimator. Adjust your primary mirror's collimation screws until the red dot lands on the laser-emitting hole in the center of the collimator viewing port and you are done. Your scope optics are collimated. \u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eFor extremely critical observing or imaging with a very fast focal ratio reflector, you might want to follow up with a star test for any final collimation tweaking that might be needed. For 99% of of your observing and imaging, however, the simple and quick laser collimation described above will be more than satisfactory.\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eThe Astro-Tech Laser Collimator's all-aluminum body measures only 4\" long, so it can easily fit into your accessory case or pocket for trips to the backyard or distant dark sky sites. It can be used with any 1.25\" telescope focuser, but also comes with a 2\" adapter at no extra cost so you can use it in any 2\" telescope focuser. \u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eThe Astro-Tech Collimator weighs only 2.4 ounces (4.8 ounces with the 2\" focuser adapter). It has a combination rotary on\/off switch and brightness control with seven brightness levels. The rotary switch is stiff in operation to avoid accidentally turning on when being stored away. It is powered by one 3V CR2032 lithium battery located in a battery compartment on top of the rotary switch.  The collimator does not come with a battery as included equipment. When installing\/ or replacing the battery, be sure to install the new battery with the positive (+) marking facing you.\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eThe \u0026lt;1mW laser diode has been factory-aligned in the collimator's body, resulting in consistently pinpoint collimation. With laser collimation quick and easy, you can keep your reflector telescope serving up the sharpest, clearest views possible, night after night, year after year.\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eWarning: The Astro-Tech Laser Collimator complies with US 21 CFR 1040.10 and 1040.11 and is FDA Certified and IEC compliant. It is a Class II laser product, and you should avoid direct eye exposure. It is not designed to be used as a toy or laser pointer. \u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003ePlease note that this product was not designed or intended by the manufacturer for use by a child 12 years of age or younger.\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003e\n\u003ctable style=\"max-width: 500px;\" id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e2.4 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481975664713,"sku":"ATLC","price":44.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/20137.jpg?v=1675379046"},{"product_id":"astro-tech-newtonian-reflector-collimating-tool","title":"Astro-Tech Newtonian Reflector Collimating Tool","description":"\u003cdiv\u003eThe Astro-Tech ATCOLL Newtonian reflector collimating tool is a combination 1.25\" sight tube and Cheshire eyepiece. It is precisely machined of aluminum and black anodized. A soft fold-down rubber eyecup (rarely found in more expensive competitive Cheshires) shields your eye from ambient light for better contrast and protects eyeglasses from being scratched during use. It's 6\" length provides higher collimating accuracy than shirter competitive Cheshires.\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eThe Astro-Tech ATCOLL has the precisely centered sighting hole and crosshairs of a sight tube, plus the cutout in the side of the tube with the precise 45° angle matte silver reflecting surface of a Cheshire eyepiece. As it is a combination tool, it is less expensive than buying a separate sight tube and Cheshire.\u003c\/div\u003e\n\u003cdiv\u003e \u003c\/div\u003e\n\u003cdiv\u003eFor the sharpest images with a Newtonian reflector, the optics must be carefully collimated (aligned). First, the diagonal mirror must be properly centered under the focuser and aimed at the primary mirror. You cannot assume that the diagonal mirror has been properly set up at the factory, or that it did not accidentally get knocked out of alignment during transport. If the diagonal is indeed out of alignment, collimating the primary mirror becomes difficult. This is particularly true with fast focal ratio (f\/4 to f\/5) reflectors, as even slight collimation errors in these systems can significantly degrade the image.\u003c\/div\u003e\n\u003cdiv\u003e \u003c\/div\u003e\n\u003cdiv\u003eUse the sight tube crosshairs of the Astro-Tech ATCOLL to confirm that your diagonal mirror is properly centered under the focuser and adjust it if needed. It then lets you adjust the tilt of the diagonal to aim it accurately at the center of the primary. Once you've set the position and orientation of the diagonal mirror with the sight tube function, use the Cheshire eyepiece function to properly align the primary mirror.\u003c\/div\u003e\n\u003cdiv\u003e \u003c\/div\u003e\n\u003cdiv\u003eThe sight tube\/Cheshire tool combination generally provides accurate enough collimation for visual use and most photography. The Astro-Tech ATCOLL collimating tool is primarily designed to be used in daylight or early twilight, but the Cheshire function can also be used in complete darkness (for those times when you can't set up until late) by shining a red flashlight into the 45° reflecting cutout in the side of the tube. Instructions on how to use the Astro-Tech ATCOLL collimating tool are included.\u003c\/div\u003e\n\u003ch2\u003e\u003cbr\u003e\u003c\/h2\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003e\n\u003ctable class=\"table\" id=\"product-attribute-specs-table\" style=\"max-width: 500px;\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e6.4 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481975697481,"sku":"ATCOLL","price":34.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/20140.jpg?v=1675379048"},{"product_id":"astro-tech-60mm-photoguide-refractor","title":"Astro-Tech 60mm Photoguide Refractor OTA","description":"\u003cp\u003eThe new Astro-Tech AT60GS 60mm guidescope with upgraded helical focuser makes highly accurate autoguiding of deep space astrophotos affordable for any astrophotographer.  The Astro-Tech AT60GS 60mm fast focal ratio guidescope adds 10mm of aperture to its 50mm predecessor to allow guiding on fainter stars, plus a new rock-solid upgraded helical focuser to eliminate any possible play in the focuser over its entire travel range.\u003c\/p\u003e\n\u003cdiv\u003eThe Astro-Tech AT60GS guidescope refractor  is superb for guiding long-exposure DSLR and CCD astrophotos. It is usable with refractors and imaging Newtonians up to 1500mm in focal length, as well as longer focal length scopes, such as the 12\" Astro-Tech Ritchey-Chrétien astrographs.\u003c\/div\u003e\n\u003cdiv\u003e \u003c\/div\u003e\n\u003cdiv\u003eTaking deep space photos used to require tedious and error-prone manual guiding through a crosshair eyepiece and a large aperture, long focal length guidescope. However, the guiding accuracy of modern CCD autoguiders allows hands-free automatic guiding of long exposure photos through smaller guidescopes with much shorter focal lengths. Using an optically \"fast\" guidescope, such as the 60mm Astro-Tech AT60GS, you save valuable time, space, and money, while still recording the pin-point star images that only autoguiding can bring to long-exposure astrophotos.\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eThe Astro-Tech AT60GS guidescope is a 60mm aperture 240mm focal length (f\/4) achromatic refractor with a helical focuser. The focuser can rotate as well to help you get the perfect framing.  It has dual mounting rings with nylon-tipped collimation screws (three per ring). The rings are attached to a riser block that uses a standard Vixen style mounting foot.  A vixen mounting shoe is included as well. Add an optional small-chip CCD autoguider, and you ready for automatic guiding.\u003c\/div\u003e\n\u003cdiv\u003e \u003c\/div\u003e\n\u003cdiv\u003eThe Astro-Tech AT60GS guidescope weighs only 20 ounces (30 ounces with the mounting rings and dovetail mounting bar). Its light weight lets you replace a heavier guidescope to gain a little breathing room with imaging setups that are pushing your mount's payload capacity. It measures 10.2\" (259mm) long with the focuser collapsed. With the focuser fully extended it measures 10.75\" long. A 48mm long fixed dew shield (with rubber dust cover) shields the fully multicoated cemented doublet lens from stray light.\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eThe  Astro-Tech guidescope's helical focuser has a lock on the rotation for your CCD autoguider during focusing. The helical focuser simply moves the attached autoguider in or out while maintaining its set orientation. This ensures that the field of potential guide stars will not rotate when focusing.\u003c\/div\u003e\n\u003cdiv\u003e  \u003c\/div\u003e\n\u003cdiv\u003eThe focuser drawtube also has a lock on it so you can't accidentally change focuser during your guiding session.\u003c\/div\u003e\n\u003cdiv\u003e \u003c\/div\u003e\n\u003cdiv\u003eThe focuser terminates in a 1.25\" accessory holder for those guiders that have a fixed 1.25\" nose piece for connecting guider to guidescope. There are also male T-threads for a more solid and secure direct attachment of a guider whose nose piece can be removed to expose female T-threads for attachment to a guidescope.\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003e\n\u003ctable style=\"max-width: 500px;\" id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e27 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481975730249,"sku":"AT60GS","price":139.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/astronomics_optimized-0076.jpg?v=1675379050"},{"product_id":"astro-tech-12-f-8-truss-tube-ritchey-chretien-optical-tube","title":"Astro-Tech 12\" f\/8 Truss Tube Ritchey-Chrétien Optical Tube","description":"\u003cdiv\u003eThis newest Version A of the Astro-Tech AT12RCT carbon fiber Serrurier truss Ritchey-Chrétien \u003cstrong\u003e\u003cem\u003e\u003cspan style=\"color: #990000;\"\u003eHot Product for 2015\u003c\/span\u003e\u003c\/em\u003e\u003c\/strong\u003e makes high quality large-aperture\/large format DSLR and CCD imaging affordable for the dedicated amateur astrophotographer and educational institution.\u003c\/div\u003e\n\u003cdiv\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003c\/span\u003e\u003c\/strong\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis newest Version A of the Astro-Tech AT12RCT Ritchey-Chrétien astrograph (named a Sky \u0026amp; Telescope Hot Product for 2015) has:\u003c\/span\u003e\u003c\/strong\u003e\u003c\/div\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e12\" f\/8 true Ritchey-Chrétien hyperbolic mirror optical design\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003ecarbon fiber Serrurier truss tube design with CNC-machined stainless steel and aluminum components\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003elow thermal expansion quartz primary and secondary mirrors \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e99% reflectivity non-tarnishing multi-layer dielectric mirror coatings \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003ethree built-in cooling fans in rear cell \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e3\" dual-speed Crayford focuser with 2\" and 1.25\" adapters \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003efocuser attachment collar isolated from the primary mirror and baffle tube\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003edust covers and finder shoe\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The original steel body Astro-Tech AT12RC was named a Sky \u0026amp; Telescope Hot Product for 2011. It joined the line-up of other Astro-Tech Ritchey-Chrétien scopes that have previously been honored by Sky \u0026amp; Telescope (the original Astro-Tech 6\" R-C was named a Hot product for 2009 and the Astro-Tech 8\" and 10\" R-Cs were named Hot Products for 2010). The Sky \u0026amp; Telescope Hot Product for 2015 carbon fiber truss-tube AT12RCT is the latest addition to that lineup, featuring the same high quality R-C optical system used in the award-winning 12\" steel body version.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e This newest version of the Astro-Tech AT12RCT makes 12\" coma-free true Ritchey-Chrétien imaging available to the DSLR and large format CCD astrophotographer at a price less than that of some large format CCD cameras by themselves.\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e Featuring first-quality 99% reflectivity dielectric mirror coatings and premium low thermal expansion quartz mirrors, rather than aluminized Pyrex glass mirrors, this reasonably-priced 12\" Astro-Tech truss-tube R-C provides the coma-free photographic field that large format CCD and DSLR astrophotographers crave, but can't get from conventional reflectors and Schmidt-Cassegrains.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e Likewise, as a pure two-mirror system, the AT12RCT has a wide spectral response and is totally free from the spurious color that affects the imaging of all but the most costly apochromatic refractors, and it does it with a 12\" aperture that dwarfs the light gathering of every commercially-available apo refractor.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e If serious astrophotography is your goal, but the price of true Ritchey-Chrétien optics has been keeping you from the optical design most modern professional observatories use, your wait is over. The 12\" Astro-Tech AT12RCT truss-tube R-C can bring the world of professional DSLR\/CCD deep space imaging to your backyard observatory at a truly affordable price.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFeatures of this Astro-Tech AT12RCT Astrograph . . .\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptical design:\u003c\/strong\u003e true Ritchey-Chrétien Cassegrain-type two-mirror optics, with hyperbolic primary and secondary mirrors. For more details, click on the \"optics\" icon above. The 288mm available back focus (from the focuser attachment collar) allows for the use of long CCD equipment trains.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptical specifications:\u003c\/strong\u003e 12\" aperture, 2432mm focal length, f\/8 focal ratio. Multiple Zygo interferometer tests, during every stage of optics manufacturing (after rough figure generation, after fine figure generation, after final polish before coating, and after dielectric coating), assure premium optical performance.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid primary mirror:\u003c\/strong\u003e Made of low thermal expansion quartz. Ground and polished under precision computer control. Unlike catadioptric designs (SCTs, Maksutovs, etc.) that move the primary mirror fore and aft in the optical tube to focus (which can lead to image shift as the mirror position changes) the AT12RCT primary mirror is fixed to eliminate both a catadioptric's image shift and the frequent primary mirror collimation requirements of a Newtonian reflector. Focusing is done by means of an optional external focuser, discussed below. Primary mirror collimation is pre-set at the factory, but can be adjusted if needed using three traditional push\/pull locking adjustment screw sets.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid secondary mirror:\u003c\/strong\u003e Made of low thermal expansion quartz, rather than Pyrex. Ground and polished under precision computer control. Mounted in a CNC-machined four-vane spider and fully collimatable using simple standard Cassegrain reflector collimating techniques. The secondary mirror is precisely center-spotted to make collimation easier. Unlike complicated R-C designs that use motors to move the secondary mirror fore and aft to focus, the AT12RCT secondary mirror is fixed and focusing is done externally by means of an optional external focuser, discussed in the focuser section below. \u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e Sky \u0026amp; Telescope said that the Astro-Tech R-C's fixed primary and secondary mirrors \"eliminate image shift, which has been the bane of Cassegrain scopes with moving-mirror focusing systems . . . It also keeps the effective focal length of the system constant, and the infinity focal point remains at a fixed point outside of the telescope, neither of which is the case with moving-mirror systems that change the separation between a Cassegrain's primary and secondary mirrors.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eCarbon fiber truss-tube design:\u003c\/strong\u003e Three CNC-machined aluminum support rings form the basic structure of the optical tube. Light-weight and rigid carbon fiber tubes connect the support rings in a Serrurier truss design, using CNC-machined stainless steel ball and socket hardware.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The Serrurier truss solves the problem of optical tube flexure by supporting the primary and secondary mirrors with two sets of opposing trusses mounted before and after the center support ring. The trusses are designed to have an equal amount of flexure, which allows the optics to stay on a common optical axis. When flexing, the \"top\" truss resists tension and the \"bottom\" truss resists compression. This has the effect of keeping the optical elements parallel to each other. The net result is that the optical elements stay in collimation regardless of the orientation of the telescope, including passing through the meridian during imaging.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The truss tubes are made of a light weight\/high strength woven carbon fiber-reinforced composite material with extremely low thermal expansion characteristics. This reduces the possibility of temperature-related focus changes that can occur with steel or aluminum optical tube scopes during extreme temperature swings.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The Astro-Tech AT12RCT is 33-1\/8\" (841mm) long without focuser. The supplied focuser adds 5.25\" (133mm) with the drawtube retracted. The center and rear truss tube support rings are 17.25\" (438mm) in diameter, while the front support ring is 15\" (381mm) in diameter. The AT12RCT weighs 49.8 lbs (22.6 kg) without focuser. The supplied focuser adds 2.2 lbs (1 kg).\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e3\" Crayford focuser: The AT12RCT is supplied with a basic light duty 3\" Crayford focuser to get you started imaging. While acceptable for casual imaging with a light imaging train (such as a light DSLR body by itself), upgrading to a high quality rack-and-pinion focuser is required for serious imaging with an optical tube of this quality. A heavy multi-component imaging train will require a rack-and-pinion focuser to support the extra weight without focus shift. Alternatively, you may already have a premium focuser being used on another scope that you would like to use for imaging.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The supplied light-duty Crayford focuser can be unthreaded from the focuser attachment collar, allowing you to use another focuser. One popular choice is the dual-speed 3\" diameter 1.5\" travel Feather Touch #3015 rack and pinion focuser, available from your Astro-Tech dealer.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The newly designed focuser attachment collar is bolted rigidly to the back plate of the AT12RCT, completely independent of the primary mirror and baffle tube. This allows it to be collimated separately from the primary and secondary mirrors if needed, using the built-in focuser collimating ring. The focuser attachment collar has a male 117m x 1mm pitch thread for attaching the focuser.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The Feather Touch #3015 normally comes with a 109mm threaded collar for connecting to a scope. Using the #3015 with the AT12RCT therefore requires an optional #M117x1 Feather Touch adapter. The #M117x1 adapter threads onto the focuser attachment port. The #3015 focuser (without its 109mm collar) then slips into the #M117x1 adapter and is held in place by three large brass Delrin-tipped retaining knobs. Only focusers with a maximum 1.5\" drawtube travel, such as the Feather Touch #3015, are recommended for use with the 12\" Astro-Tech AT12RCT Ritchey-Chrétien. For other focusers, such as a MoonLite, contact the focuser manufacturer for an adapter to fit the 117mm x 1mm port on the rear of the scope.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e To fine-tune the 288mm back focus of the AT12RCT to the requirements of your camera and equipment train, three threaded extension rings (one 2\" and two 1\" in length) are provided to thread singly or in combination between the 117mm port on the AT12RCT rear cell and the focuser of your choice. These provide a flex-free solid metal extension that changes the distance between your chosen focuser and the rear cell. This lets you accommodate the varying back-focus requirements of DSLR-type camera imaging versus long equipment train CCD imaging. The 2\" threaded ring weighs 14.4 ounces, the 1\" rings weigh 7.2 ounces each.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eCooling fans:\u003c\/strong\u003e To allow the AT12RCT to reach ambient temperatures more quickly for optimum imaging performance, there are three small low vibration\/high CFM primary mirror cooling fans built into the rear cell. The high speed DC fans are powered by a standard equipment battery pack that plugs into a jack on the rear cell. The battery pack uses eight user-supplied AA batteries. An optional external DC power supply, such as a rechargeable 12VDC battery pack can also be used to power the fans.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eTwo dovetail mounting rails:\u003c\/strong\u003e Two 14\" Losmandy-style \"D-plate\" dovetail rails are bolted to the top and bottom of the center and rear truss-tube support rings. These allow you to install the AT12RCT directly on an equatorial mount and mount optional accessories (such as rings for a photoguide scope that attach to a scope by means of Losmandy-style \"D-plate\" dovetail adapters. The undersides of the dovetails have been hollowed out to lighten their weight without compromising their strength.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOther accessories:\u003c\/strong\u003e This new Version A of the AT12RCT includes slip-on dust covers for both the primary and secondary mirrors. Also included is a mounting shoe for a red dot-type finder, such as the Astro-Tech ATF. The mounting shoe can also accept the Astro-Tech ATF50QRB 50mm finderscope quick release bracket.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch2\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTech Details: \u003c\/span\u003e\u003c\/h2\u003e\n\u003ctable style=\"max-width: 500px;\" id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eAperture\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e12\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e2432mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eFocal Ratio\u003c\/th\u003e\n\u003ctd class=\"data\"\u003ef\/8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eHeaviest Single Component\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e49.8 pounds\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e52 lbs.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eResolution\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e0.38 arc seconds\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eTelescope Type\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eRitchey-Chrétien\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eBack Focus\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e11.33 (288mm) from rear cell\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481975926857,"sku":"AT12RCT","price":4495.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/20148.jpg?v=1675379064"},{"product_id":"astro-tech-14-f-8-truss-tube-ritchey-chretien-optical-tube","title":"Astro-Tech 14\" f\/8 Truss Tube Ritchey-Chrétien Optical Tube","description":"\u003cspan style=\"font-size: 17px; line-height: 22px; font-family: tahoma, verdana, sans-serif; background-color: #ffffff;\"\u003e\u003cspan style=\"color: #17161d;\"\u003eThis new version of the \u003c\/span\u003e\u003cstrong\u003e\u003cem\u003e\u003cspan style=\"color: #990000;\"\u003eHot Product for 2015\u003c\/span\u003e\u003c\/em\u003e\u003c\/strong\u003e\u003cspan style=\"color: #17161d;\"\u003e Astro-Tech AT14RCT carbon fiber truss Ritchey-Chrétien makes high quality DSLR and CCD imaging affordable for the dedicated amateur astrophotographer and educational institution.\u003c\/span\u003e\u003c\/span\u003e\n\u003cdiv\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis newest Version A of the Astro-Tech AT14RCT Ritchey-Chrétien astrograph (named a Sky \u0026amp; Telescope Hot Product for 2015) has:\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e14\" f\/8 true Ritchey-Chrétien hyperbolic mirror optical design\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003ecarbon fiber Serrurier truss tube design with CNC-machined stainless steel and aluminum components\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003elow thermal expansion quartz primary and secondary mirrors \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003ethree built-in cooling fans in rear cell \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e3\" dual-speed compression ring Crayford focuser with 2\" and 1.25\" adapters \u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003efocuser attachment collar isolated from the primary mirror and baffle tube\u003c\/span\u003e\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003edust covers and finder shoe\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e \"Overall I'm very impressed with the AT14RCT. It's a great scope for visual observing as well as deep-sky photography. The lack of a field flattener limits its use with the largest CCDs, but that's not a handicap for anyone working with smaller detectors up to and including any of the highly popular KAF-8300-based cameras. And when you factor in the scope's cost, it's an outstanding value. It's a winner!\" Dennis di Cicco, in a 4-page review in the July 2016 Sky and Telescope.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eThis newest version of the Astro-Tech AT14RCT makes 14\" coma-free true Ritchey-Chrétien imaging available to the DSLR and large format CCD astrophotographer at a price less than that of some large format CCD cameras by themselves. \u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e Featuring first-quality premium low thermal expansion quartz mirrors, rather than aluminized Pyrex glass mirrors, this reasonably-priced 14\" Astro-Tech truss-tube R-C provides the coma-free photographic field that large format CCD and DSLR astrophotographers crave, but can't get from conventional reflectors and Schmidt-Cassegrains.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e Likewise, as a pure two-mirror system, the AT14RCT has a wide spectral response and is totally free from the spurious color that affects the imaging of all but the most costly apochromatic refractors, and it does it with a 14\" aperture that dwarfs the light gathering of every commercially-available apo refractor.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e If serious astrophotography is your goal, but the price of true Ritchey-Chrétien optics has been keeping you from the optical design most modern professional observatories use, your wait is over. The 14\" Astro-Tech AT14RCT truss-tube R-C can bring the world of professional DSLR\/CCD deep space imaging to your backyard observatory at a truly affordable price.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eFeatures of this Astro-Tech AT14RCT Ritchey-Chrétien . . .\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOptical design:\u003c\/strong\u003e True Ritchey-Chrétien Cassegrain-type two-mirror optics, with hyperbolic primary and secondary mirrors. The 288mm usable back focus (from the end of the focuser attachment port) allows for the use of long CCD equipment trains.\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eOptical specifications: 14\" aperture, 2850mm focal length, f\/8 focal ratio. Multiple Zygo interferometer tests, during every stage of optics manufacturing (after rough figure generation, after fine figure generation, after final polish before coating, and after dielectric coating), assure premium optical performance.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid primary mirror:\u003c\/strong\u003e Made of low thermal expansion quartz. Ground and polished under precision computer control. Unlike catadioptric designs (SCTs, Maksutovs, etc.) that move the primary mirror fore and aft in the optical tube to focus (which can lead to image shift and a changing focal length and focal ratio as the mirror position changes) the AT14RCT's non-moving primary mirror is supported by a multi-point floatation system. Primary mirror collimation is pre-set at the factory, but can be adjusted if needed using three heavy-duty spring-loaded push\/pull locking adjustment screw sets.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eHyperboloid secondary mirror:\u003c\/strong\u003e Made of low thermal expansion quartz, rather than Pyrex. Ground and polished under precision computer control. Mounted in a CNC-machined four-vane spider and fully collimatable using standard Cassegrain reflector collimating techniques. The secondary mirror is precisely center-spotted to make collimation easier.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e Unlike complicated R-C designs that use motors to move the secondary mirror fore and aft to focus, the AT14RCT secondary mirror is fixed and focusing is done externally by means of an optional external focuser, discussed in the focuser section below. \u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e Sky \u0026amp; Telescope said that the Astro-Tech R-C's fixed primary and secondary mirrors \"eliminate image shift, which has been the bane of Cassegrain scopes with moving-mirror focusing systems . . . It also keeps the effective focal length of the system constant, and the infinity focal point remains at a fixed point outside of the telescope, neither of which is the case with moving-mirror systems that change the separation between a Cassegrain's primary and secondary mirrors.\"\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The secondary mirror's baffle obstruction is 6.5\" (166mm) in diameter (46.6% by diameter and 21.7% by area of the 14\" primary.)\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eCarbon fiber truss-tube design:\u003c\/strong\u003e Four CNC-machined aluminum support rings form the basic structure of the optical tube. Light-weight and rigid carbon fiber tubes connect the support rings in a Serrurier truss design, using CNC-machined stainless steel ball and socket hardware. The middle and rear support rings have a hexagonal outer shape, measuring 20.5\" (521mm) across at their widest point. They are 10mm thick. The dual front support rings provide attachment points for the secondary mirror spider vanes, as well as for the truss tubes. They measure 17.75\" (451mm) across at their widest point of their hexagonal outer shape and are 5mm thick. The AT14RCT measures only 33\" long (1156mm) from the front support ring to the end of the focuser mounting collar, and weighs 65 pounds (29.5kg) without focuser.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The Serrurier truss solves the problem of optical tube flexure by supporting the primary and secondary mirrors with two sets of opposing trusses mounted before and after the center support ring. The trusses are designed to have an equal amount of flexure, which allows the optics to stay on a common optical axis. When flexing, the \"top\" truss resists tension and the \"bottom\" truss resists compression. This has the effect of keeping the optical elements parallel to each other. The net result is that the optical elements stay in collimation regardless of the orientation of the telescope, including when passing through the meridian during imaging.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The truss tubes are made of a light weight\/high strength woven carbon fiber-reinforced composite material with extremely low thermal expansion characteristics. This reduces the possibility of temperature-related focus changes that can occur with steel or aluminum optical tube scopes during extreme temperature swings.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The Astro-Tech AT14RCT is 39\" (991mm) long without focuser. The supplied focuser adds 5.25\" (133mm) with the drawtube retracted. The center and rear truss tube support rings are 19\" (483mm) in diameter, while the front support ring is 16.5\" (419mm) in diameter. The AT14RCT weighs 65 lbs (29.5 kg) without focuser. The supplied focuser adds 2.2 lbs (1 kg).\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e3\" Crayford focuser: The AT14RCT is supplied with a basic light duty 3\" Crayford focuser to get you started imaging. While acceptable for casual imaging with a light imaging train (such as a light DSLR body by itself), upgrading to a high quality rack-and-pinion focuser is required for serious imaging with an optical tube of this quality. A heavy multi-component imaging train will require a rack-and-pinion focuser to support the extra weight without focus shift. Alternatively, you may already have a premium focuser being used on another scope that you would like to use for imaging.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The supplied light-duty Crayford focuser can be unthreaded from the focuser attachment collar, allowing you to use another focuser. One popular choice is the dual-speed 3\" diameter 1.5\" travel Feather Touch #3015 rack and pinion focuser, available from your Astro-Tech dealer.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The newly designed focuser attachment collar is bolted rigidly to the back plate of the AT14RCT, completely independent of the primary mirror and baffle tube. This allows it to be collimated separately from the primary and secondary mirrors if needed, using the built-in focuser collimating ring. The focuser attachment collar has a male 117m x 1mm pitch thread for attaching the focuser.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e The Feather Touch #3015 normally comes with a 109mm threaded collar for connecting to a scope. Using the #3015 with the AT14RCT therefore requires an optional #M117x1 Feather Touch adapter. The #M117x1 adapter threads onto the focuser attachment port. The #3015 focuser (without its 109mm collar) then slips into the #M117x1 adapter and is held in place by three large brass Delrin-tipped retaining knobs. Only focusers with a maximum 1.5\" drawtube travel, such as the Feather Touch #3015, are recommended for use with the 14\" Astro-Tech AT14RCT Ritchey-Chrétien. For other focusers, such as a MoonLite, contact the focuser manufacturer for an adapter to fit the 117mm x 1mm port on the rear of the scope.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eBack focus:\u003c\/strong\u003e To fine-tune the 288mm usable back focus of the AT14RCT to the requirements of your camera and equipment train, three threaded extension rings (one 2\" and two 1\" in length) are provided to thread singly or in combination between the focuser attachment collar and the focuser of your choice. These rings provide a flex-free solid metal extension that changes the distance between your chosen focuser and the rear cell. This lets you accommodate the varying back-focus requirements of DSLR-type camera imaging versus long equipment train CCD imaging. The 2\" threaded ring weighs 14.4 ounces, the 1\" rings weigh 7.2 ounces each.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eMount requirements:\u003c\/strong\u003e Because of the 65 pound (29.5 kg) weight of the AT14RCT, plus the weight of your focuser, ancillary camera equipment, and any photoguide scope, installing the AT14RCT on a German equatorial mount with a 90 to 100 pound minimum payload capacity is recommended. Such mounts include the Losmandy 100 pound capacity Losmandy HGM Titan; the 220 pound capacity Astro-Physics 1600GTO; and the 90 pound Software Bisque Paramount MX or 240 pound capacity Paramount ME II. Other suitable mounts are also available.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eCooling fans:\u003c\/strong\u003e To allow the AT14RCT to reach ambient temperatures more quickly for optimum imaging performance, there are three low vibration\/high CFM primary mirror cooling fans built into the AT14RCT's rear support truss\/back plate. The high speed DC fans are powered by a standard equipment battery pack that plugs into a 5mm female jack in the back plate. The battery pack uses eight user-supplied AA batteries. An optional external DC power supply, such as a rechargeable 12VDC battery pack can also be used to power the fans.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eTwo dovetail mounting rails:\u003c\/strong\u003e Two 15.5\" (394mm) Losmandy-style \"D-plate\" dovetail rails are bolted to the top and bottom of the center and rear truss-tube support rings. These allow you to install the AT14RCT directly on an equatorial mount and mount optional accessories (such as rings for a photoguide scope) that attach to a scope by means of Losmandy-style \"D-plate\" dovetail adapters. The undersides of the dovetails have been hollowed out to lighten their weight without compromising their strength.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003e\u003cstrong\u003eOther accessories:\u003c\/strong\u003e This new Version A of the AT14RCT includes slip-on dust covers for both the primary and secondary mirrors. Also included is a mounting shoe for a red dot-type finder, such as the Astro-Tech ATF. The mounting shoe can also accept the Astro-Tech ATF50QRB 50mm finderscope quick release bracket.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch2\u003e\u003cspan style=\"font-family: arial, helvetica, sans-serif; font-size: medium;\"\u003eTech Details: \u003c\/span\u003e\u003c\/h2\u003e\n\u003ctable style=\"max-width: 500px;\" id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eAperture\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e14\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eFocal Length\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e2850mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eFocal Ratio\u003c\/th\u003e\n\u003ctd class=\"data\"\u003ef\/8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eHeaviest Single Component\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e65 pounds\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWeight\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e65 lbs.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eTelescope Type\u003c\/th\u003e\n\u003ctd class=\"data\"\u003eRitchey-Chrétien\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 25%;\"\u003eBack Focus\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e288mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481976778825,"sku":"AT14RCT","price":6049.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/20181.jpg?v=1675379108"}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/collections\/69F40BB5-0F50-48E5-BBE2-AB7476520AB6.jpg?v=1678524987","url":"https:\/\/astronomics.com\/collections\/astro-tech.oembed?page=7","provider":"Astronomics","version":"1.0","type":"link"}