{"title":"Field Flatteners","description":"","products":[{"product_id":"large-field-corrector-for-ccd-imaging-with-np-101is-np-127is","title":"TeleVue Large Field Corrector for CCD Imaging with NP-101is\/NP-127is","description":"\u003cp\u003eThis auxiliary multicoated lens system sharpens 35mm and large format CCD images taken through the TeleVue NP-101is and NP-127is imaging system refractors only. The lens flattens the normally slightly curved refractor field to provide tightly-focused pinpoint star images across the entire field for deep space photography. It does it without changing the effective focal length or focal ratio of the scope. It is recommended for cameras using large format CCD chips, such as the SBIG Research Series STL-11000M and 11000CM which have CCD chips the size of a 35mm negative, as well as those cameras with still larger chips (greater than the 36mm x 24.7mm chips of the STL-11000 models).\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 oz.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e5 years\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"TeleVue","offers":[{"title":"Default Title","offer_id":40221652746313,"sku":"1360","price":343.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/12389_1.jpg?v=1662967327"},{"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-at60ed-field-flattener","title":"Astro-Tech AT60ED Field Flattener","description":"\u003cp\u003eThis thread on field flattener for the AT60ED is a must for full frame photography.The Astro-Tech 60ED 1x flattener easily threads on to the focuser of your AT60ED after your remove the standard compression ring eyepiece holder. The flattener produces wonderful flat fields as well as a 41mm image circle.\u003c\/p\u003e\n\u003cp\u003eThe threads on the t-ring side of the flattener are 48mm male. Make sure your t-ring will work with this particular flattener. The standard for years has been 42mm and not 48mm, so please double check your equipment.\u003c\/p\u003e\n\u003cp\u003eBackfocus from the rear shoulder of the AT60FF to the image plane is 54.8mm, so you may require some additional spacers to reach focus.\u003c\/p\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481982873673,"sku":"AT60FF","price":119.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/img_5841.jpg?v=1675379503"},{"product_id":"explore-scientific-3-field-flattener-7x-focal-reducer","title":"Explore Scientific 3\" Field Flattener .7x Focal Reducer","description":"\u003cp\u003e\u003cspan\u003eExplore Scientific’s 3” Field Flattener .7x Focal Reducer is a multi-faceted accessory designed to enhance your astrophotography experiences.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003eThe Explore Scientific 3\" Field Flattener\/.7x Focal Reducer is designed to increase your photographic enjoyment of your Explore Scientific refractor.  Depending on which refractor you own, you might need an additional adapter.  Out of the box you will be able to attach it to the 3\" Explore Scientific focuser.  However, you will need the #510366 adapter if you have the 2.5\" Hex focuser, or the 510364 adapter if you have the 2\" Explore Scientific focuser, to attach this piece of equipment to your scope.  \u003c\/p\u003e\n\u003cp\u003eOnce installed you should notice a few things.  1.  The stars are pinpoint out to the edge of your camera, no more curvature.  2. You will notice more sky in your field as you have reduced your f\/ratio by .7x.  And finally 3.  Your exposure times will  have decreased and your images will be brighter due to the faster optic.  \u003c\/p\u003e\n\u003cp\u003eExplore Scientific has thought of everything.  The device is fully multi-coated to help maximize light transmission, and it also comes standard with adapters to help your camera\/DSLR\/CCD attach.\u003c\/p\u003e\n\u003cp\u003eThis piece really works well from f\/8 to f\/7.5.\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\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year, extendable to lifetime\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":40481983594569,"sku":"ES3FF","price":299.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/f1_1493x_a6f9b499-81ca-4bfe-9c41-784353fe5654.jpg?v=1675379560"},{"product_id":"explore-scientific-adapter-for-3-field-flattener-7x-reducer-to-attach-to-2-5-hex-focuser","title":"Explore Scientific Adapter For 3\" Field Flattener .7x Reducer To Attach To 2.5\" Hex Focuser","description":"\u003cp\u003e \u003c\/p\u003e\n\u003ch3 data-end=\"414\" data-start=\"316\"\u003eExplore Scientific Adapter for 3\" Field Flattener \/ 0.7x Reducer to Attach to 2.5\" Hex Focuser\u003c\/h3\u003e\n\u003cp data-end=\"810\" data-start=\"416\"\u003eIf you're using the Explore Scientific 2.5\" Hex Focuser and looking to expand your astrophotography capabilities, this dedicated adapter lets you seamlessly integrate the Explore Scientific 3\" Field Flattener \/ 0.7x Reducer with your imaging setup. It’s a simple yet critical upgrade for achieving pinpoint stars across a wider field and reducing your effective focal length for faster imaging.\u003c\/p\u003e\n\u003ch4 data-end=\"856\" data-start=\"812\"\u003ePrecision Fit and Optical Compatibility\u003c\/h4\u003e\n\u003cp data-end=\"1202\" data-start=\"858\"\u003eDesigned specifically by Explore Scientific, this adapter ensures a secure mechanical connection between your 2.5\" Hexagonal focuser and the larger 3\" flattener\/reducer assembly. This is not a generic part — it's engineered for precise alignment and rigidity to maintain the critical backfocus and optical path required for optimal performance.\u003c\/p\u003e\n\u003cp data-end=\"1468\" data-start=\"1204\"\u003eThe adapter threads directly onto the rear of the 2.5\" Hex Focuser, replacing the standard 2\" or 2.5\" visual back. On the flattener\/reducer side, it accepts the 3\" component with an exact fit, ensuring no tilt, flex, or misalignment that could degrade your images.\u003c\/p\u003e\n\u003ch4 data-end=\"1504\" data-start=\"1470\"\u003eDesigned for Astrophotography\u003c\/h4\u003e\n\u003cp data-end=\"1892\" data-start=\"1506\"\u003eThis adapter exists purely for imagers. When combined with the 3\" Field Flattener \/ 0.7x Reducer, you'll get a flatter, wider field with reduced vignetting, making it perfect for full-frame and APS-C sensors. The reducer drops your focal ratio by 30%, allowing for shorter exposures and improved performance with faint targets — ideal for nebulae, wide star fields, and larger galaxies.\u003c\/p\u003e\n\u003cp data-end=\"2125\" data-start=\"1894\"\u003eWhether you're using an Explore Scientific ED102, ED127, or other compatible refractor with a 2.5\" Hex Focuser, this adapter makes it possible to expand your system with the more robust 3\" optics designed for larger-format imaging.\u003c\/p\u003e\n\u003ch4 data-end=\"2145\" data-start=\"2127\"\u003eBuilt to Last\u003c\/h4\u003e\n\u003cp data-end=\"2438\" data-start=\"2147\"\u003eMachined from high-quality aluminum with a black anodized finish, this adapter is both durable and lightweight. The internal surfaces are matte black to reduce stray reflections and maintain image contrast. Threading is clean and precise, providing a solid mechanical lock with minimal play.\u003c\/p\u003e\n\u003ch4 data-end=\"2464\" data-start=\"2440\"\u003eNo Tools, No Hassle\u003c\/h4\u003e\n\u003cp data-end=\"2773\" data-start=\"2466\"\u003eInstallation is straightforward. Simply unthread the existing rear accessory collar from your 2.5\" Hex Focuser, thread on the adapter, and then connect your 3\" reducer\/flattener. Once everything is locked into place, you're ready to attach your imaging train and begin capturing sharper, wider-field images.\u003c\/p\u003e\n\u003ch4 data-end=\"2793\" data-start=\"2775\"\u003eKey Features:\u003c\/h4\u003e\n\u003cul data-end=\"3180\" data-start=\"2795\"\u003e\n\u003cli data-end=\"2892\" data-start=\"2795\"\u003eAllows attachment of Explore Scientific 3\" Field Flattener \/ 0.7x Reducer to 2.5\" Hex Focuser\u003c\/li\u003e\n\u003cli data-end=\"2942\" data-start=\"2893\"\u003eCustom-threaded for perfect fit and alignment\u003c\/li\u003e\n\u003cli data-end=\"2997\" data-start=\"2943\"\u003eMaintains critical backfocus and optical integrity\u003c\/li\u003e\n\u003cli data-end=\"3047\" data-start=\"2998\"\u003eIdeal for full-frame and APS-C sensor cameras\u003c\/li\u003e\n\u003cli data-end=\"3119\" data-start=\"3048\"\u003eMachined aluminum construction with anti-reflective interior finish\u003c\/li\u003e\n\u003cli data-end=\"3180\" data-start=\"3120\"\u003eSimple installation — no modifications or tools required\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4 data-end=\"3197\" data-start=\"3182\"\u003eIn Summary\u003c\/h4\u003e\n\u003cp data-end=\"3521\" data-start=\"3199\"\u003eIf you're serious about wide-field astrophotography and want to take full advantage of your Explore Scientific optics, this adapter is an essential piece of the puzzle. It bridges the gap between your high-precision focuser and the power of the 3\" reducer\/flattener system, unlocking better image quality across the board.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: -apple-system, BlinkMacSystemFont, 'San Francisco', 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif; font-size: 0.875rem;\"\u003eTech Details: \u003c\/span\u003e\u003c\/p\u003e\n\u003ctable id=\"product-attribute-specs-table\" class=\"table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eWarranty\u003c\/th\u003e\n\u003ctd class=\"data\"\u003e1 year, extendable to lifetime\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":40481983660105,"sku":"510366","price":89.99,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/es_0510366_1_1493x_106f2c37-8542-462b-a913-b1267ce664bf.jpg?v=1675379566"},{"product_id":"astro-tech-152mm-edt-72x-reducer-field-flattener","title":"Astro-Tech AT152EDT .8X Reducer Field Flattener","description":"\u003cp\u003eThe Astro-Tech AT152FF 0.8x focal reducer\/field flattener is designed specifically for prime focus astrophotography with the AT152EDT triplet refractor.\u003c\/p\u003e\n\u003cp\u003eThe fully-multicoated reducer\/flattener converts the 1216mm fl 152EDT into an 973mm f\/6.4 photographic system.\u003c\/p\u003e\n\u003cp\u003eNot only do you get to speed up your scope, it will also flatten the normal field curvature inherent in all refractors.\u003c\/p\u003e\n\u003cp\u003eInstallation is simple. Just unthread the 2\" adapter from the focuser drawtube. This will expose the 92mm threads. Now, just thread the AT152FF in its place and you are ready to go.\u003c\/p\u003e\n\u003cp\u003eThe camera side of the reducer has 48mm t-threads, so make sure your t-ring will work.\u003c\/p\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481985069129,"sku":"AT152FF","price":299.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/at152ffbw.jpg?v=1675379657"},{"product_id":"astro-tech-8x-reducer-field-flattener-for-the-60ed-and-72ed-optical-tubes","title":"Astro-Tech .8X Reducer Field Flattener For The 72EDII Optical Tubes","description":"Looking to make your Astro-Tech (or variant) scope faster and flatter for photography?  Then the .8x reducer\/flattener is exactly what your are looking for.\u003cp\u003eWhile this Astro-Tech ATRF72 0.8X reducer\/field flattener is designed for prime focus astrophotography with the Astro-Tech  AT72EDII, it will work with other variants of the same optical tube. Feel free to give us a call if you have a question about your scope if it isn’t an Astro-Tech product. 800-422-7876\u003c\/p\u003e\n\u003cp\u003eThe fully-multicoated Astro-Tech ATRF72 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.\u003c\/p\u003e\n\u003cp\u003eIn addition to reducing the focal length of the telescope and thereby increasing the photographic speed, the ATRF72 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.\u003c\/p\u003e\n\u003cp\u003eThe Astro-Tech ATRF72 reducer\/flattener threads on the 72EDII focusers. The flattener is threaded for attachment to the telescope via a 54mm metric thread. The camera side of the reducer has 48mm T-threads to connect to a T-ring and camera body. Back focus is 55mm from the shoulder of the reducer to the image plane, the standard spacing for 35mm and DSLR camera bodies.\u003c\/p\u003e\n\u003cp\u003eThe interior of the telescope side of the reducer\/field flattener is a 48mm female thread so standard 2\" filters can thread right in.\u003c\/p\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481989001289,"sku":"ATRF72","price":159.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/Astronomics-Astronomy-Store-telescopes-78.png?v=1714677676"},{"product_id":"astro-tech-8x-reducer-field-flattener-for-the-60ed-optical-tubes","title":"Astro-Tech .8X Reducer Field Flattener For The 60ED Optical Tubes","description":"Looking to make your Astro-Tech (or variant) scope faster and flatter for photography?  Then the .8x reducer\/flattener is exactly what your are looking for.\u003cp\u003eWhile this Astro-Tech ATRF60 0.8X reducer\/field flattener is designed for prime focus astrophotography with the Astro-Tech  AT60ED, it will work with other variants of the same optical tube. Feel free to give us a call if you have a question about your scope if it isn’t an Astro-Tech product. 800-422-7876\u003c\/p\u003e\r\n\u003cp\u003eThe fully-multicoated Astro-Tech ATRF60 converts the 360mm focal length f\/6 Astro-Tech AT60ED refractor into a 288mm f\/4.8 lens for faster and wider field astronomical and terrestrial photography.\u003c\/p\u003e\r\n\u003cp\u003eIn addition to reducing the focal length of the telescope and thereby increasing the photographic speed, the ATRF60 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.\u003c\/p\u003e\r\n\u003cp\u003eThe Astro-Tech ATRF60 reducer\/flattener threads on the 60ED focusers. The flattener is threaded for attachment to the telescope via a 54mm metric thread. The camera side of the reducer has 48mm T-threads to connect to a T-ring and camera body. Back focus is 55mm from the shoulder of the reducer to the image plane, the standard spacing for 35mm and DSLR camera bodies.\u003c\/p\u003e\r\n\u003cp\u003eThe interior of the telescope side of the reducer\/field flattener is a 48mm female thread so standard 2\" filters can thread right in.\u003c\/p\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481989034057,"sku":"ATRF60","price":159.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/Astronomics-Astronomy-Store-telescopes-87.png?v=1714677601"},{"product_id":"astro-tech-0-8x-reducer-field-flattener-for-astro-tech-at115edt-triplet-apo-refractor","title":"Astro-Tech 0.8X Reducer\/Field Flattener For Astro-Tech AT115EDT Triplet APO Refractor Version II","description":"\u003cp\u003eYou've got 115mm of ED triplet glass pointed at the sky. The AT115EDT's optics deliver clean color correction — three FK-61 elements working together the way they should. But point a camera at the focal plane and the triplet shows you what it doesn't correct natively: field curvature. Center stars are tight and round. Corner stars are not. They stretch, they soften, they remind you that a refractor designed for visual use doesn't automatically produce flat-field images. The ATREDT15V2 fixes that. It flattens the field and reduces the focal length at the same time — converting 805mm f\/7 into 644mm f\/5.6 with sharp, corrected stars across your sensor.\u003c\/p\u003e\n\u003cp\u003eThat focal reduction matters more than the number suggests. At f\/5.6, your exposures run approximately 36% shorter than at f\/7 for the same signal. On a narrowband target at 5-minute subs, that's real time saved — or, looked at another way, significantly more signal per frame. The wider field of view means objects that were tight fits at 805mm now have room to breathe. The Rosette Nebula, the Orion Nebula, the Veil Nebula — they all frame more comfortably at 644mm than they do at native focal length.\u003c\/p\u003e\n\u003cp\u003eThe ATREDT15V2 threads into the focuser drawtube or camera angle adjuster of the AT115EDT via M63×1 threads. This is a secure, rigid connection — no barrel slip, no adapter stack flexing under your camera's weight. The camera side uses standard 48mm T-threads, connecting to a T-ring for DSLR and mirrorless bodies, or directly to dedicated CMOS and CCD astronomy cameras, which come with 48mm T-threads built in. Back focus is 55mm from the reducer shoulder to the image plane, which is the standard spacing for most DSLR T-ring combinations and dedicated camera setups.\u003c\/p\u003e\n\u003cp\u003eFully multi-coated with broadband anti-reflection coatings on all optical surfaces. Slip-on rubber dust covers are included for both ends — scope side and camera side — to protect the coated glass between imaging sessions.\u003c\/p\u003e\n\u003ch3\u003eImportant: Which Reducer for Which Focuser\u003c\/h3\u003e\n\u003cp\u003eThe AT115EDT has been produced with different focuser versions over its production run. This reducer — the ATREDT15V2 — is designed for the 2.5-inch focuser with M63×1 drawtube threads. If your AT115EDT has the newer 3.2-inch focuser with M92 drawtube threads, you would want to consider the AT115EDTRFv3 instead. However, this model will work the the 3.2\" focuser, it just won't produce as large an image circle. \u003c\/p\u003e\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eAstro-Tech ATREDT15V2 0.8× reducer\/field flattener\u003c\/li\u003e\n\u003cli\u003eSlip-on rubber dust cover (scope side)\u003c\/li\u003e\n\u003cli\u003eSlip-on rubber dust cover (camera side)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e0.8× focal reduction\u003c\/strong\u003e — Converts the AT115EDT from 805mm f\/7 to 644mm f\/5.6. Approximately 36% shorter exposures for the same signal, and a meaningfully wider field of view for framing large deep-sky objects.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eField flattener integrated\u003c\/strong\u003e — Corrects the native field curvature of the AT115EDT triplet. Stars stay sharp and round from center to corner across your imaging sensor. No separate flattener needed.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM63×1 scope-side connection\u003c\/strong\u003e — Threads directly into the AT115EDT's 2.5-inch focuser drawtube or camera angle adjuster. Rigid, secure, no barrel slip or flexure under camera weight.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e48mm T-threads on camera side\u003c\/strong\u003e — DSLR and mirrorless bodies connect via a T-ring for your specific mount (sold separately). Dedicated CMOS and CCD astronomy cameras attach directly — 48mm T-threads are standard on most.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e55mm back focus\u003c\/strong\u003e — Standard spacing from reducer shoulder to image plane. Most DSLR T-ring combinations and dedicated camera setups reach this distance naturally. If your setup differs, shim with T-thread spacers to hit 55mm precisely.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFully multi-coated optics\u003c\/strong\u003e — Broadband anti-reflection coatings on all surfaces. Contrast is preserved and internal reflections are controlled — important for narrowband work where stray light shows up fast.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDust covers included\u003c\/strong\u003e — Slip-on rubber covers for both ends. Protect the coated surfaces when the reducer isn't on the scope.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompact, lightweight\u003c\/strong\u003e — Adds minimal weight and length to your imaging train. The AT115EDT's balance point barely shifts.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eObserving Tip\u003c\/h3\u003e\n\u003cp\u003eGetting the back focus right is the single most important thing you can do with this reducer. At 55mm, the field correction is optimized — sharp stars to the corners. Too short or too long, and you'll see elongated stars at the edges that no amount of post-processing will fix. Measure from the reducer's shoulder (the flat face where it meets the T-ring or camera adapter) to your sensor. A set of T-thread spacers (AT4220 and AT4230) lets you dial in the exact distance. It's worth spending ten minutes with a ruler before your first imaging session — the results on screen will tell you immediately whether you got it right.\u003c\/p\u003e\n\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eDo I need a T-ring to connect my camera?\u003c\/strong\u003e\u003cbr\u003eIt depends on your camera. Dedicated CMOS and CCD astronomy cameras (ZWO, QHY, Player One, and similar) typically have 48mm T-threads built in and connect directly to the ATREDT15V2 — no T-ring needed. DSLR and mirrorless cameras (Canon, Nikon, Sony, and others) connect via a T-ring for your specific lens mount. The T-ring is sold separately.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use filters with this reducer?\u003c\/strong\u003e\u003cbr\u003eThe ATREDT15V2 does have an internal filter threads like the V3 version. Just unthread the knurled ring on the top of the reducer to expose the fitler threads on the underside of it.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat happens if my back focus is off?\u003c\/strong\u003e\u003cbr\u003eYou'll see elongated or distorted stars at the edges of your images — the field correction is optimized for 55mm. Too short and stars stretch one way; too long and they stretch the other. Use T-thread spacers to fine-tune the distance. Measure from the reducer shoulder to your sensor before your first session.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use this with other telescopes?\u003c\/strong\u003e\u003cbr\u003eIt may work with other f\/7 refractors that have a 2.5-inch focuser with M63×1 threads, but we can only confirm performance with the AT115EDT. The optical design is matched to the AT115EDT's focal length and field curvature. Using it with other scopes may produce usable results, but we can't guarantee corner correction.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow does this compare to the 1× field flattener?\u003c\/strong\u003e\u003cbr\u003eThe 1× flattener (AT115EDTFF) corrects field curvature without changing the focal length — you stay at 805mm f\/7. The 0.8× reducer (this product) both flattens the field and shortens the focal length to 644mm f\/5.6. Use the 1× flattener when you want maximum image scale and don't need faster exposures. Use the 0.8× reducer when you want a wider field and shorter exposures. Most AT115EDT imagers end up using the reducer more often.\u003c\/p\u003e\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\u003cp\u003eIf you're imaging with an AT115EDT that has the 2.5-inch focuser, the ATREDT15V2 is the reducer that was designed for it. The optical correction is matched to the AT115EDT's triplet, the M63 threading gives you a rigid connection without adapter stacks, and 644mm at f\/5.6 opens up the wide-field deep-sky targets that are cramped at native focal length. It does two things — flattens the field and speeds up the system — and it does both well. Get the back focus right at 55mm, and the corners of your frames will tell you the rest.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse;\"\u003e\n\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eATREDT15V2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCompatible Telescope\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAT115EDT (2.5\" and 3.2\" Grey focusers)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFocal Reduction\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e0.8×\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e644mm (from 805mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Ratio\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003ef\/5.6 (from f\/7)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eScope Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM63×1 threads (into 2.5\" focuser drawtube or CAA)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e48mm T-threads\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBack Focus\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e55mm (reducer shoulder to sensor)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCoatings\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFully multi-coated, broadband AR\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eIncluded Accessories\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSlip-on rubber dust covers (scope side and camera side)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481992736841,"sku":"ATREDT15V2","price":229.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/astronomics_optimized-0056.jpg?v=1675380119"},{"product_id":"astro-tech-0-8x-reducer-field-flattener-for-astro-tech-at130edt-triplet-apo-refractor","title":"Astro-Tech 0.8X Reducer\/Field Flattener For Astro-Tech AT130EDT Triplet APO Refractor Version II","description":"\u003cp\u003eYou've got 130mm of ED triplet glass pointed at the sky. The AT130EDT's optics deliver clean color correction — three FK-61 elements working together the way they should. But point a camera at the focal plane and the triplet shows you what it doesn't correct natively: field curvature. Center stars are tight and round. Corner stars are not. They stretch, they soften, they remind you that a refractor designed for visual use doesn't automatically produce flat-field images. The ATREDT30V2 fixes that. It flattens the field and reduces the focal length at the same time — converting 910mm f\/7 into 728mm f\/5.6 with sharp, corrected stars across your sensor.\u003c\/p\u003e\n\u003cp\u003eThat focal reduction matters more than the number suggests. At f\/5.6, your exposures run approximately 36% shorter than at f\/7 for the same signal. On a narrowband target at 5-minute subs, that's real time saved — or, looked at another way, significantly more signal per frame. The wider field of view means objects that were tight fits at 910mm now have room to breathe. The Rosette Nebula, the North America Nebula complex, the California Nebula — they all frame more comfortably at 728mm than they do at native focal length.\u003c\/p\u003e\n\u003cp\u003eThe ATREDT30V2 threads into the focuser drawtube or camera angle adjuster of the AT130EDT via M63×1 threads. This is a secure, rigid connection — no barrel slip, no adapter stack flexing under your camera's weight. The camera side uses standard 48mm T-threads, connecting to a T-ring for DSLR and mirrorless bodies, or directly to dedicated CMOS and CCD astronomy cameras, which come with 48mm T-threads built in. Back focus is 55mm from the reducer shoulder to the image plane, which is the standard spacing for most DSLR T-ring combinations and dedicated camera setups.\u003c\/p\u003e\n\u003cp\u003eFully multi-coated with broadband anti-reflection coatings on all optical surfaces. Slip-on rubber dust covers are included for both ends — scope side and camera side — to protect the coated glass between imaging sessions.\u003c\/p\u003e\n\u003ch3\u003eImportant: Which Reducer for Which Focuser\u003c\/h3\u003e\n\u003cp\u003eThe AT130EDT has been produced with different focuser versions over its production run. This reducer — the ATREDT30V2 — is designed for the 2.5-inch focuser with M63×1 drawtube threads, but it can work with the new 3.2\" focuser. If your AT130EDT has the newer 3.2-inch focuser with M92 drawtube threads, you might want to consider the  AT130EDTRFv3 as it produces a larger image circle.  This reducer will also not work with the original black-bodied focuser model. If you're not sure which focuser you have, check the drawtube diameter or call us.\u003c\/p\u003e\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eAstro-Tech ATREDT30V2 0.8× reducer\/field flattener\u003c\/li\u003e\n\u003cli\u003eSlip-on rubber dust cover (scope side)\u003c\/li\u003e\n\u003cli\u003eSlip-on rubber dust cover (camera side)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e0.8× focal reduction\u003c\/strong\u003e — Converts the AT130EDT from 910mm f\/7 to 728mm f\/5.6. Approximately 36% shorter exposures for the same signal, and a meaningfully wider field of view for framing large deep-sky objects.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eField flattener integrated\u003c\/strong\u003e — Corrects the native field curvature of the AT130EDT triplet. Stars stay sharp and round from center to corner across your imaging sensor. No separate flattener needed.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM63×1 scope-side connection\u003c\/strong\u003e — Threads directly into the AT130EDT's 2.5-inch focuser drawtube or camera angle adjuster. Rigid, secure, no barrel slip or flexure under camera weight.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e48mm T-threads on camera side\u003c\/strong\u003e — DSLR and mirrorless bodies connect via a T-ring for your specific mount (sold separately). Dedicated CMOS and CCD astronomy cameras attach directly — 48mm T-threads are standard on most.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e55mm back focus\u003c\/strong\u003e — Standard spacing from reducer shoulder to image plane. Most DSLR T-ring combinations and dedicated camera setups reach this distance naturally. If your setup differs, shim with T-thread spacers to hit 55mm precisely.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFully multi-coated optics\u003c\/strong\u003e — Broadband anti-reflection coatings on all surfaces. Contrast is preserved and internal reflections are controlled — important for narrowband work where stray light shows up fast.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDust covers included\u003c\/strong\u003e — Slip-on rubber covers for both ends. Protect the coated surfaces when the reducer isn't on the scope.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompact, lightweight\u003c\/strong\u003e — Adds minimal weight and length to your imaging train. The AT130EDT's balance point barely shifts.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eObserving Tip\u003c\/h3\u003e\n\u003cp\u003eGetting the back focus right is the single most important thing you can do with this reducer. At 55mm, the field correction is optimized — sharp stars to the corners. Too short or too long, and you'll see elongated stars at the edges that no amount of post-processing will fix. Measure from the reducer's shoulder (the flat face where it meets the T-ring or camera adapter) to your sensor. A set of T-thread spacers (AT4220 and AT4230) lets you dial in the exact distance. It's worth spending ten minutes with a ruler before your first imaging session — the results on screen will tell you immediately whether you got it right.\u003c\/p\u003e\n\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eWill this work on the AT130EDT with the 3.2-inch focuser?\u003c\/strong\u003e\u003cbr\u003eYes. This reducer uses M63×1 threads which you can access on the 3.2\" focuser. \u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDo I need a T-ring to connect my camera?\u003c\/strong\u003e\u003cbr\u003eIt depends on your camera. Dedicated CMOS and CCD astronomy cameras (ZWO, QHY, Player One, and similar) typically have 48mm T-threads built in and connect directly to the ATREDT30V2 — no T-ring needed. DSLR and mirrorless cameras (Canon, Nikon, Sony, and others) connect via a T-ring for your specific lens mount. The T-ring is sold separately.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use filters with this reducer?\u003c\/strong\u003e\u003cbr\u003eThe ATREDT30V2 does have the internal filter threads when you thread off the knurled end cap.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat happens if my back focus is off?\u003c\/strong\u003e\u003cbr\u003eYou'll see elongated or distorted stars at the edges of your images — the field correction is optimized for 55mm. Too short and stars stretch one way; too long and they stretch the other. Use T-thread spacers to fine-tune the distance. Measure from the reducer shoulder to your sensor before your first session.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use this with other telescopes?\u003c\/strong\u003e\u003cbr\u003eIt may work with other f\/7 refractors that have a 2.5-inch focuser with M63×1 threads, but we can only confirm performance with the AT130EDT. The optical design is matched to the AT130EDT's focal length and field curvature. Using it with other scopes may produce usable results, but we can't guarantee corner correction.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow does this compare to the 1× field flattener?\u003c\/strong\u003e\u003cbr\u003eThe 1× flattener (AT130EDTFF) corrects field curvature without changing the focal length — you stay at 910mm f\/7. The 0.8× reducer (this product) both flattens the field and shortens the focal length to 728mm f\/5.6. Use the 1× flattener when you want maximum image scale and don't need faster exposures. Use the 0.8× reducer when you want a wider field and shorter exposures. Most AT130EDT imagers end up using the reducer more often.\u003c\/p\u003e\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\u003cp\u003eIf you're imaging with an AT130EDT that has the 2.5-inch focuser, the ATREDT30V2 is the reducer that was designed for it. The optical correction is matched to the AT130EDT's triplet, the M63 threading gives you a rigid connection without adapter stacks, and 728mm at f\/5.6 opens up the wide-field deep-sky targets that are cramped at native focal length. It does two things — flattens the field and speeds up the system — and it does both well. Get the back focus right at 55mm, and the corners of your frames will tell you the rest.\u003c\/p\u003e\n\u003ch2\u003eTech Details: \u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse;\"\u003e\n\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eATREDT30V2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCompatible Telescope\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAT130EDT (2.5\" focuser or 3.2\" focuser)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFocal Reduction\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e0.8×\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e728mm (from 910mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Ratio\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003ef\/5.6 (from f\/7)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eScope Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM63×1 threads (into 2.5\" focuser drawtube or CAA)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e48mm T-threads\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBack Focus\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e55mm (reducer shoulder to sensor)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCoatings\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFully multi-coated, broadband AR\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eIncluded Accessories\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSlip-on rubber dust covers (scope side and camera side)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481992769609,"sku":"ATREDT30V2","price":229.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/products\/astronomics_optimized-0053.jpg?v=1675380122"},{"product_id":"astro-tech-0-8x-reducer-field-flattener-for-astro-tech-at102edl-doublet-apo-refractor","title":"Astro-Tech 0.8X Reducer\/Field Flattener For Astro-Tech AT102EDL Doublet Apo Refractor","description":"\u003cp\u003eThe AT102EDL is a versatile doublet APO at 714mm f\/7 — plenty of focal length for mid-range targets and sharp enough for visual work on any given night. But when you attach a camera, the field curvature that's invisible at the eyepiece becomes obvious in your images. Stars that are tight in the center soften into small streaks near the corners. The AT102EDLRF corrects that curvature and reduces the focal length to 571mm f\/5.6 — a 56% increase in photographic speed — so you get flat fields, round stars, and shorter exposures in one piece of glass.\u003c\/p\u003e\n\n\u003ch3\u003eDesigned for One Scope\u003c\/h3\u003e\n\n\u003cp\u003eThis reducer\/flattener is computed specifically for the field curvature of the Astro-Tech AT102EDL 102mm f\/7 doublet APO refractor. A generic 0.8x reducer will shorten the focal length, but it won't match the correction to your scope's specific optical profile. This one does. It may thread into other f\/7 refractors with a 2.5-inch focuser, but optical performance outside the AT102EDL is not guaranteed.\u003c\/p\u003e\n\n\u003ch3\u003eHow It Connects\u003c\/h3\u003e\n\n\u003cp\u003eThe scope side threads into the focuser drawtube using M63×1 metric threads — a solid, repeatable connection with no compression ring and no play. The camera side has standard 48mm T-threads, connecting to a T-ring for DSLR and mirrorless bodies, or directly to dedicated CMOS and CCD astronomy cameras, which come with 48mm T-threads built in.\u003c\/p\u003e\n\n\u003cp\u003eBack focus is 55mm from the shoulder of the reducer to the image plane. That's the standard DSLR spacing — a T-ring and camera body will put you at the correct distance without spacers. For dedicated astronomy cameras, measure your camera's back focus specification and add spacers if needed to reach 55mm.\u003c\/p\u003e\n\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\n\u003cul\u003e\n  \u003cli\u003eAstro-Tech AT102EDLRF 0.8x reducer\/field flattener\u003c\/li\u003e\n  \u003cli\u003eSlip-on rubber dust cover for 48mm T-threads (camera side)\u003c\/li\u003e\n  \u003cli\u003eSlip-on dust cover for 2\" scope-side barrel\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e0.8x focal reduction\u003c\/strong\u003e — Converts the AT102EDL from 714mm f\/7 to 571mm f\/5.6. That's a 56% increase in photographic speed — the same signal-to-noise ratio in roughly two-thirds the exposure time.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eField flattening\u003c\/strong\u003e — Corrects the native field curvature of the AT102EDL so stars stay round and sharp all the way to the corners of your imaging chip.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFully multi-coated optics\u003c\/strong\u003e — Minimizes reflections and maximizes light transmission through the reducer elements.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eM63×1 scope-side thread\u003c\/strong\u003e — Threads securely into the focuser drawtube. No set screws, no wobble, no shift between sessions.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e48mm T-thread camera connection\u003c\/strong\u003e — DSLR and mirrorless bodies connect via a T-ring (sold separately); dedicated CMOS\/CCD astronomy cameras attach directly — 48mm T-threads are standard on most.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e55mm back focus\u003c\/strong\u003e — Standard DSLR spacing. No spacers needed for most DSLR setups. Dedicated astronomy cameras may require spacers to reach the correct distance.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCompact and lightweight\u003c\/strong\u003e — 8 ounces. Adds minimal weight to your imaging train.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eImaging Tip\u003c\/h3\u003e\n\n\u003cp\u003eWhen you first set up the AT102EDLRF, shoot a short test exposure of a star field and inspect the corners at 100% zoom. If stars are elongated radially (pointing away from center), you're too far from the reducer — remove a spacer or check your T-ring stack. If stars are elongated tangentially (perpendicular to the radial direction), you're too close. The 55mm specification is measured from the shoulder of the reducer, not the rear element — make sure you're measuring from the right reference point.\u003c\/p\u003e\n\n\u003ch3\u003eFAQ\u003c\/h3\u003e\n\n\u003cp\u003e\u003cstrong\u003eWill this work with my AT125EDL or AT150EDL?\u003c\/strong\u003e\u003cbr\u003e\nNo. Each EDL scope has its own dedicated reducer matched to its specific field curvature. The AT125EDL uses the AT125EDLRF, and the AT150EDL uses the AT150EDLRF. They are not interchangeable.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eCan I use this visually?\u003c\/strong\u003e\u003cbr\u003e\nThe reducer is designed for prime-focus astrophotography. It will not reach focus with an eyepiece and is not intended for visual use.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eDo I need a T-ring?\u003c\/strong\u003e\u003cbr\u003e\nDSLR and mirrorless cameras connect via a T-ring for your specific mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat sensors have been tested with this reducer?\u003c\/strong\u003e\u003cbr\u003e\nOwners report sharp stars to the edges of 4\/3-format sensors (like the ASI-294mc) at the specified 55mm back focus. Results on larger APS-C and full-frame sensors will depend on precise spacing — test and adjust before committing to long integration times.\u003c\/p\u003e\n\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\n\u003cp\u003eIf you're imaging through the AT102EDL, this is the reducer that was built for it. It flattens the field, speeds the system to f\/5.6, and threads in with a secure M63 connection that holds position between sessions. At 8 ounces, it barely changes the balance of your imaging train. The AT102EDL is already one of the most capable doublets in its aperture class — the AT102EDLRF turns it into a proper imaging platform with flat fields and faster exposures.\u003c\/p\u003e\n\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width:100%; border-collapse: collapse;\"\u003e\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eReduction Factor\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e0.8x\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eDesigned For\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAstro-Tech AT102EDL 102mm f\/7 Doublet APO Refractor\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eNative Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e714mm f\/7\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e571mm f\/5.6\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCoatings\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFully multi-coated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eScope-Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM63×1 metric thread (focuser drawtube)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera-Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e48mm T-threads\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBack Focus\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e55mm (from shoulder of reducer to image plane)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003ePhotographic Speed Increase\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e56% (f\/7 to f\/5.6)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWeight\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e8 oz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eIncluded\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eReducer\/flattener, T-thread dust cover, scope-side dust cover\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWarranty\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481994244169,"sku":"AT102EDLRF","price":199.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/0.8XReducer_Flattener_1-10522.jpg?v=1714680170"},{"product_id":"astro-tech-0-8x-reducer-field-flattener-for-astro-tech-at125edl-doublet-apo-refractor","title":"Astro-Tech 0.8X Reducer\/Field Flattener For Astro-Tech AT125EDL Doublet APO Refractor","description":"\u003cp\u003eThe AT125EDL is a serious visual scope at 975mm f\/7.8, but when you turn it toward astrophotography, two things work against you: the curved field stretches stars into small comets near the corners of your sensor, and the slow focal ratio means longer exposures to capture the same depth of signal. The AT125EDLRF fixes both. It reduces the focal length to 780mm, speeding the system to f\/6.2 — a 56% increase in photographic speed — and flattens the field so stars stay round and tight from center to edge.\u003c\/p\u003e\n\n\u003ch3\u003eDesigned for One Scope\u003c\/h3\u003e\n\n\u003cp\u003eThis reducer\/flattener is not a universal accessory. It's computed and optimized for the field curvature profile of the Astro-Tech AT125EDL 125mm f\/7.8 doublet APO refractor. A generic 0.8x reducer can shorten focal length, but it won't correct the specific curvature of your scope. This one does. It may thread into other f\/7.8 refractors with a 2.5-inch focuser, but optical performance is only guaranteed with the AT125EDL.\u003c\/p\u003e\n\n\u003ch3\u003eHow It Connects\u003c\/h3\u003e\n\n\u003cp\u003eThe scope side threads into the focuser drawtube or the camera angle adjuster (CAA) using M63×1 metric threads — a secure, repeatable connection with no set screws and no wobble. The camera side has standard 48mm T-threads, connecting to a T-ring for DSLR and mirrorless bodies, or directly to dedicated CMOS and CCD astronomy cameras, which come with 48mm T-threads built in.\u003c\/p\u003e\n\n\u003cp\u003eBack focus is 55mm from the shoulder of the reducer to the image plane. That's the standard DSLR spacing — a T-ring and camera body will put you at the correct distance without spacers. For dedicated astronomy cameras, measure your camera's back focus and add spacers if needed to reach 55mm.\u003c\/p\u003e\n\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\n\u003cul\u003e\n  \u003cli\u003eAstro-Tech AT125EDLRF 0.8x reducer\/field flattener\u003c\/li\u003e\n  \u003cli\u003eSlip-on rubber dust cover for 48mm T-threads (camera side)\u003c\/li\u003e\n  \u003cli\u003eSlip-on dust cover for 2\" scope-side barrel\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e0.8x focal reduction\u003c\/strong\u003e — Converts the AT125EDL from 975mm f\/7.8 to 780mm f\/6.2. That's a 56% increase in photographic speed — the same target reaches the same signal-to-noise ratio in roughly two-thirds the exposure time.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eField flattening\u003c\/strong\u003e — Corrects the native field curvature of the AT125EDL so stars are round and sharp all the way to the corners of your imaging chip.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFully multi-coated optics\u003c\/strong\u003e — Minimizes reflections and maximizes light transmission through the reducer elements.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eM63×1 scope-side thread\u003c\/strong\u003e — Threads securely into the focuser drawtube or camera angle adjuster. No compression ring, no wobble, no shift between sessions.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e48mm T-thread camera connection\u003c\/strong\u003e — DSLR and mirrorless bodies connect via a T-ring (sold separately); dedicated CMOS\/CCD astronomy cameras attach directly — 48mm T-threads are standard on most.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e55mm back focus\u003c\/strong\u003e — Standard DSLR spacing. No spacers needed for most DSLR setups. Dedicated astronomy cameras may require spacers to reach the correct distance.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCompact and lightweight\u003c\/strong\u003e — 8 ounces. Adds minimal weight to your imaging train.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eImaging Tip\u003c\/h3\u003e\n\n\u003cp\u003eWhen you first set up the AT125EDLRF, shoot a short test exposure of a star field and inspect the corners at 100% zoom. If stars are elongated radially (pointing away from center), you're too far from the reducer — remove a spacer or check your T-ring stack. If stars are elongated tangentially (perpendicular to the radial direction), you're too close. The 55mm specification is measured from the shoulder of the reducer, not the rear element — make sure you're measuring from the right point.\u003c\/p\u003e\n\n\u003ch3\u003eFAQ\u003c\/h3\u003e\n\n\u003cp\u003e\u003cstrong\u003eWill this work with my AT102EDL or AT150EDL?\u003c\/strong\u003e\u003cbr\u003e\nNo. Each EDL scope has its own dedicated reducer matched to its specific field curvature. The AT102EDL uses the AT102EDLRF, and the AT150EDL uses the AT150EDLRF. They are not interchangeable.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eCan I use this visually?\u003c\/strong\u003e\u003cbr\u003e\nThe reducer is designed for prime-focus astrophotography. It will not reach focus with an eyepiece and is not intended for visual use.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eDo I need a T-ring?\u003c\/strong\u003e\u003cbr\u003e\nDSLR and mirrorless cameras connect via a T-ring for your specific mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat if I need to use a filter?\u003c\/strong\u003e\u003cbr\u003e\nYou can place a 48mm (2\") threaded filter between the reducer and the camera. Be aware that adding a filter changes your back focus distance — account for the filter thickness when calculating your total spacing.\u003c\/p\u003e\n\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\n\u003cp\u003eIf you're imaging through the AT125EDL, this is the reducer that was designed for it. It flattens the field, speeds the system to f\/6.2, and threads in with a secure M63 connection that doesn't shift between sessions. At 8 ounces, it adds almost nothing to your imaging train. The result is sharper corners, shorter exposures, and a wider field — exactly what the AT125EDL needs to go from a visual scope that happens to image to a proper astrophotography platform.\u003c\/p\u003e\n\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width:100%; border-collapse: collapse;\"\u003e\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eReduction Factor\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e0.8x\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eDesigned For\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAstro-Tech AT125EDL 125mm f\/7.8 Doublet APO Refractor\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eNative Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e975mm f\/7.8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e780mm f\/6.2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCoatings\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFully multi-coated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eScope-Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM63×1 metric thread (focuser drawtube or CAA)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera-Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e48mm T-threads\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBack Focus\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e55mm (from shoulder of reducer to image plane)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003ePhotographic Speed Increase\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e56% (f\/7.8 to f\/6.2)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWeight\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e8 oz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eIncluded\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eReducer\/flattener, T-thread dust cover, scope-side dust cover\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWarranty\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":40481994276937,"sku":"AT125EDLRF","price":199.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/0.8XReducer_Flattener_1-10522_3885e071-8109-44bc-8473-2f2480333cd7.jpg?v=1714677371"},{"product_id":"astro-tech-0-8x-reducer-field-flattener-for-astro-tech-at90cft-triplet-apo-refractor","title":"Astro-Tech 0.8x Reducer\/Field Flattener for Astro-Tech AT90CFT and AT90EDX Triplet APO Refractor","description":"\u003cp\u003eThe AT90CFT and AT90EDX are excellent visual scopes at 540mm f\/6, but if you're imaging through either one, you already know the two things an f\/6 refractor does to your photos: it curves the field and it makes you wait. Stars that are pin-sharp in the center turn into little comets near the corners. And at f\/6, you need longer exposures to pull faint nebulosity out of the background. The AT90CFTRF fixes both problems in one piece of glass. It reduces the focal length to 432mm, speeding the system to f\/4.8 — a 56% increase in photographic speed — and it flattens the field so stars stay round and tight all the way to the corners of your imaging chip.\u003c\/p\u003e\n\u003ch3\u003eDesigned for Two Scopes\u003c\/h3\u003e\n\u003cp\u003eThis reducer\/flattener is not a universal fit. It's designed and optimized specifically for the Astro-Tech AT90CFT (carbon fiber tube) and AT90EDX (aluminum tube) 90mm f\/6 triplet APO refractors. The optical correction is matched to the curvature profile of those two scopes, which is why the stars come out round across the field instead of trailing into elongated shapes at the edges. A generic 0.8x reducer can reduce focal length, but it won't correct the specific field curvature of your scope. This one does.\u003c\/p\u003e\n\u003ch3\u003eHow It Connects\u003c\/h3\u003e\n\u003cp\u003eThe scope side threads into the focuser or camera angle adjuster using M63×1 metric threads — a secure, repeatable connection that doesn't shift between sessions. No set screws, no compression ring, no wobble. The camera side has standard 48mm T-threads, connecting to a T-ring for DSLR and mirrorless bodies, or directly to dedicated CMOS and CCD astronomy cameras, which come with 48mm T-threads built in.\u003c\/p\u003e\n\u003cp\u003eBack focus is 55mm from the shoulder of the reducer to the image plane. That's the standard DSLR spacing — meaning a T-ring and camera body will put you at the correct distance without spacers or adjustments. For dedicated astronomy cameras, you may need a short spacer to reach the same 55mm. Check your camera's back focus specification and add spacers if needed.\u003c\/p\u003e\n\u003ch3\u003eBuilt-In Filter Holder\u003c\/h3\u003e\n\u003cp\u003eThe top cap of the reducer unthreads from the body, exposing a 48mm filter holder on the underside. This lets you place a 2\" threaded filter — a light pollution filter, narrowband filter, or UV\/IR cut — directly into the optical path without adding a separate filter drawer to your imaging train. One less piece of hardware between the scope and the sensor, and one less source of spacing error or tilt.\u003c\/p\u003e\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eAstro-Tech AT90CFTRF 0.8x reducer\/field flattener\u003c\/li\u003e\n\u003cli\u003eSlip-on rubber dust cover for 48mm T-threads (camera side)\u003c\/li\u003e\n\u003cli\u003eSlip-on dust cover for scope-side barrel\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e0.8x focal reduction — 540mm f\/6 becomes 432mm f\/4.8\u003c\/strong\u003e — A 56% increase in photographic speed (light per pixel). Shorter exposures to reach the same signal, or deeper images in the same exposure time. Either way, your total imaging time per target drops significantly.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eField flattening corrects edge-of-field curvature\u003c\/strong\u003e — Refractors curve the focal plane. Without correction, stars in the outer third of the field elongate into streaks or comets. The flattener brings the entire field into focus on a flat imaging sensor, producing round stars corner to corner.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFully multi-coated optics\u003c\/strong\u003e — All air-to-glass surfaces are multi-coated to minimize reflections and maintain contrast. Important in a reducer that sits in the optical path of every photon reaching your sensor.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM63×1 threaded scope connection\u003c\/strong\u003e — Threads securely into the AT90CFT\/AT90EDX focuser or camera angle adjuster. No compression ring, no play — a solid, repeatable mechanical connection that eliminates tilt between sessions.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e48mm T-thread camera connection\u003c\/strong\u003e — DSLR and mirrorless bodies connect via a T-ring (sold separately); dedicated CMOS\/CCD astronomy cameras attach directly — 48mm T-threads are standard on most.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e55mm back focus (standard DSLR spacing)\u003c\/strong\u003e — A T-ring and DSLR body reach focus without spacers. Dedicated astronomy cameras may need a short spacer depending on their native back focus distance. The product manual includes spacing diagrams.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIntegrated 48mm filter holder\u003c\/strong\u003e — Unthread the top cap to access a built-in 2\" filter holder. Accepts standard 48mm threaded filters — narrowband, UHC, UV\/IR cut — without adding a separate filter drawer to the imaging train.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLightweight (9 oz)\u003c\/strong\u003e — Adds minimal weight to your imaging train. Won't stress the focuser or shift balance on a light mount.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eObserving Tip\u003c\/h3\u003e\n\u003cp\u003eGet the 55mm back focus right before you shoot a single frame. Measure from the shoulder of the reducer — the flat face where it meets the focuser — to your camera sensor. For a DSLR with a T-ring, 55mm is usually automatic. For a dedicated astronomy camera, add up the T-ring or adapter thickness, any spacers, and the camera's flange-to-sensor distance. If the total is less than 55mm, add spacers. If it's more, you'll need a shorter adapter or fewer spacers. Getting this measurement right is the single biggest factor in whether your corner stars are round or elongated. The product manual has a spacing diagram — use it.\u003c\/p\u003e\n\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eQ: Do I need a T-ring?\u003c\/strong\u003e\u003cbr\u003eIf you're using a DSLR or mirrorless camera, yes — you need a T-ring for your specific camera mount (sold separately). The reducer's camera side has 48mm T-threads that connect to the T-ring. If you're using a dedicated CMOS or CCD astronomy camera, no T-ring is needed — those cameras typically have 48mm T-threads built in and connect directly to the reducer.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eQ: Can I use filters with this reducer?\u003c\/strong\u003e\u003cbr\u003eYes. Unthread the top cap of the reducer to expose a built-in 48mm filter holder on the underside. Standard 2\" threaded filters (48mm) thread right in — narrowband, light pollution, UV\/IR cut. The filter sits inside the reducer body, keeping your imaging train compact.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eQ: What's the correct back focus distance?\u003c\/strong\u003e\u003cbr\u003e55mm from the shoulder of the reducer (where it meets the focuser) to the image plane (your camera sensor). For a DSLR with a standard T-ring, this spacing is typically automatic. For a dedicated astronomy camera, you may need to add spacers to reach 55mm. Incorrect spacing is the most common cause of elongated corner stars — it's worth measuring carefully. The included product manual has a spacing diagram for common camera configurations.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eQ: How much faster is f\/4.8 compared to f\/6?\u003c\/strong\u003e\u003cbr\u003eAbout 56% faster in terms of light gathered per pixel per unit time. In practical terms, if you were shooting 5-minute exposures at f\/6 to reach a certain signal level, you'd reach the same level in roughly 3 minutes and 12 seconds at f\/4.8. Over a multi-hour session, that adds up to significantly more data or significantly less time on each target.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eQ: Will this work for visual observing?\u003c\/strong\u003e\u003cbr\u003eTechnically yes — it will reduce magnification and widen the field, and the flattening will improve edge sharpness in wide-field eyepieces. But it's designed and optimized for photographic use with a flat sensor, not for visual observing through an eyepiece. Most AT90CFT\/AT90EDX owners use the reducer strictly for imaging and observe without it.\u003c\/p\u003e\n\u003ch3\u003eOptional Accessories\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e48mm T-Ring (for your camera mount)\u003c\/strong\u003e — Required for DSLR and mirrorless cameras. Available for Canon EF, Nikon F, Sony E, and other mounts. The T-ring threads onto the reducer's 48mm camera-side connection and adapts it to your camera body. Not needed for dedicated CMOS\/CCD astronomy cameras.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e48mm Threaded Filters\u003c\/strong\u003e — Light pollution, narrowband (H-alpha, O-III, S-II), or UV\/IR cut filters thread directly into the reducer's built-in filter holder. No separate filter drawer required.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSpacer Rings (if using a dedicated astronomy camera)\u003c\/strong\u003e — Needed to achieve the 55mm back focus distance with cameras that have a shorter native back focus than a DSLR. Available in various thicknesses (e.g., 11mm, 16.5mm, 21mm). Check your camera's specs and add spacers to make up the difference.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\u003cp\u003eIf you own an AT90CFT or AT90EDX and you're imaging with it, this is not an optional accessory — it's the other half of the imaging system. The scope gives you the light and the color correction. The reducer gives you the speed and the flat field. Stars round to the corners, exposures cut by more than a third, and the whole thing threads together without adapters or guesswork. Dedicated, matched, done.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse;\"\u003e\n\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eProduct Type\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFocal reducer and field flattener\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eReduction Factor\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e0.8x\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCompatible Telescopes\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAstro-Tech AT90CFT and AT90EDX 90mm f\/6 triplet APO refractors\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e432mm (from 540mm native)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Ratio\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003ef\/4.8 (from f\/6 native)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCoatings\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFully multi-coated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eScope-Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM63×1 metric thread (threads into focuser or camera angle adjuster)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera-Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e48mm T-thread\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBack Focus\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e55mm (shoulder of reducer to image plane)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFilter Holder\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eBuilt-in 48mm (2\") threaded filter holder (accessible by unthreading top cap)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWeight\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e9 oz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eIncluded\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eReducer\/flattener, slip-on rubber cover for T-threads, slip-on cover for scope-side barrel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eProduct Manual\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eIncluded (PDF download on product page)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWarranty\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e1 year manufacturer warranty\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":41403600961609,"sku":"AT90CFTRF","price":199.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/image_fd016b25-9d57-4773-9219-2d18891ff86c.jpg?v=1716199025"},{"product_id":"explore-scientific-2-field-flattener-for-imaging-for-f-5-to-f-7-refractors","title":"Explore Scientific 2\" Field Flattener for Imaging for f\/5 to f\/7 Refractors","description":"\u003ch3 data-end=\"277\" data-start=\"194\"\u003eExplore Scientific 2\" Field Flattener – Precision Imaging for Fast Refractors\u003c\/h3\u003e\n\u003cp data-end=\"684\" data-start=\"279\"\u003eIf you're a deep-sky astrophotographer using a fast refractor, you’ve likely encountered the frustration of field curvature—stars near the center of your image look pinpoint sharp, but those toward the edges turn into bloated, misshapen blurs. That’s where the \u003cstrong data-end=\"581\" data-start=\"540\"\u003eExplore Scientific 2\" Field Flattener\u003c\/strong\u003e steps in, offering a simple yet powerful solution to transform your telescope’s imaging performance.\u003c\/p\u003e\n\u003cp data-end=\"1114\" data-start=\"686\"\u003eDesigned for refractors with focal ratios between \u003cstrong data-end=\"751\" data-start=\"736\"\u003ef\/5 and f\/7\u003c\/strong\u003e, this high-quality optical accessory ensures your stars remain sharp and well-defined across the entire field of view, eliminating the curved focal plane that distorts stars at the periphery of your images. Whether you’re capturing wide-field nebulae, open clusters, or galaxies, this flattener helps you maximize the full potential of your refractor’s optics.\u003c\/p\u003e\n\u003ch4 data-end=\"1153\" data-start=\"1116\"\u003e\u003cstrong data-end=\"1151\" data-start=\"1121\"\u003eWhy Use a Field Flattener?\u003c\/strong\u003e\u003c\/h4\u003e\n\u003cp data-end=\"1510\" data-start=\"1154\"\u003eRefractors, especially faster ones, inherently suffer from field curvature—a natural optical aberration that causes stars to appear in focus at the center while progressively blurring toward the edges. This is particularly noticeable in full-frame or APS-C sensor astrophotography, where the larger sensor size reveals these distortions more prominently.\u003c\/p\u003e\n\u003cp data-end=\"1755\" data-start=\"1512\"\u003eThe \u003cstrong data-end=\"1557\" data-start=\"1516\"\u003eExplore Scientific 2\" Field Flattener\u003c\/strong\u003e corrects this issue by adjusting the light path so that every star, from the center to the very edge, lands on the same focal plane. The result? Stunning, pinpoint stars across your entire image.\u003c\/p\u003e\n\u003ch4 data-end=\"1780\" data-start=\"1757\"\u003e\u003cstrong data-end=\"1778\" data-start=\"1762\"\u003eKey Features\u003c\/strong\u003e\u003c\/h4\u003e\n\u003cul data-end=\"2806\" data-start=\"1782\"\u003e\n\u003cli data-end=\"1970\" data-start=\"1782\"\u003e\n\u003cstrong data-end=\"1823\" data-start=\"1784\"\u003eOptimized for f\/5 to f\/7 refractors\u003c\/strong\u003e – Designed to match the optical characteristics of fast refractors, providing the best balance of correction for a wide range of imaging setups.\u003c\/li\u003e\n\u003cli data-end=\"2115\" data-start=\"1971\"\u003e\n\u003cstrong data-end=\"1999\" data-start=\"1973\"\u003eLarge 2\" barrel design\u003c\/strong\u003e – Ensures full-frame sensor coverage without vignetting, preserving a bright, even field across your astrophotos.\u003c\/li\u003e\n\u003cli data-end=\"2274\" data-start=\"2116\"\u003e\n\u003cstrong data-end=\"2147\" data-start=\"2118\"\u003eFully multi-coated optics\u003c\/strong\u003e – Reduces reflections and increases light transmission, improving contrast and preserving faint details in deep-sky objects.\u003c\/li\u003e\n\u003cli data-end=\"2456\" data-start=\"2275\"\u003e\n\u003cstrong data-end=\"2301\" data-start=\"2277\"\u003eThreaded for filters\u003c\/strong\u003e – The 2\" nosepiece includes standard filter threads, allowing you to seamlessly integrate light pollution or narrowband filters into your imaging train.\u003c\/li\u003e\n\u003cli data-end=\"2658\" data-start=\"2457\"\u003e\n\u003cstrong data-end=\"2490\" data-start=\"2459\"\u003eVersatile camera connection\u003c\/strong\u003e – The flattener terminates in a standard \u003cstrong data-end=\"2548\" data-start=\"2532\"\u003eM42 T-thread\u003c\/strong\u003e, making it easy to attach most DSLR and dedicated astronomy cameras with the appropriate T-ring or adapter.\u003c\/li\u003e\n\u003cli data-end=\"2806\" data-start=\"2659\"\u003e\n\u003cstrong data-end=\"2687\" data-start=\"2661\"\u003eAll-metal construction\u003c\/strong\u003e – A robust and precisely machined aluminum housing ensures durability while maintaining excellent optical alignment.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4 data-end=\"2853\" data-start=\"2808\"\u003e\u003cstrong data-end=\"2851\" data-start=\"2813\"\u003eHow It Works in Your Imaging Setup\u003c\/strong\u003e\u003c\/h4\u003e\n\u003cp data-end=\"3237\" data-start=\"2854\"\u003eUsing the \u003cstrong data-end=\"2905\" data-start=\"2864\"\u003eExplore Scientific 2\" Field Flattener\u003c\/strong\u003e is as simple as inserting it into your focuser, attaching your camera, and fine-tuning your back focus. This flattener is designed for use with \u003cstrong data-end=\"3072\" data-start=\"3050\"\u003e55mm of back focus\u003c\/strong\u003e, which is standard for most astrophotography setups, meaning it will work seamlessly with your DSLR and T-ring or dedicated astro camera with appropriate spacers.\u003c\/p\u003e\n\u003cp data-end=\"3540\" data-start=\"3239\"\u003eIf you’re unsure about your specific back focus requirements, adjusting with additional extension rings may be necessary for optimal performance. The results, however, are well worth it—razor-sharp stars across your entire image, making your astrophotos look more professional and visually striking.\u003c\/p\u003e\n\u003ch4 data-end=\"3588\" data-start=\"3542\"\u003e\u003cstrong data-end=\"3586\" data-start=\"3547\"\u003eWho Should Consider This Flattener?\u003c\/strong\u003e\u003c\/h4\u003e\n\u003cp data-end=\"3905\" data-start=\"3589\"\u003eThis field flattener is a must-have for astrophotographers using fast refractors who want to eliminate edge distortions without altering their telescope’s native focal length. It’s particularly well-suited for those with \u003cstrong data-end=\"3862\" data-start=\"3810\"\u003e80mm to 130mm refractors in the f\/5 to f\/7 range\u003c\/strong\u003e, ensuring a wide range of compatibility.\u003c\/p\u003e\n\u003cp data-end=\"4088\" data-start=\"3907\"\u003eFor those looking to enhance their imaging without the added complexity of a reducer-flattener combo, this straightforward, high-performance solution delivers exceptional results.\u003c\/p\u003e\n\u003ch4 data-end=\"4115\" data-start=\"4090\"\u003e\u003cstrong data-end=\"4113\" data-start=\"4095\"\u003eFinal Thoughts\u003c\/strong\u003e\u003c\/h4\u003e\n\u003cp data-end=\"4481\" data-start=\"4116\"\u003eAstrophotography demands precision, and the \u003cstrong data-end=\"4201\" data-start=\"4160\"\u003eExplore Scientific 2\" Field Flattener\u003c\/strong\u003e is an essential tool for anyone looking to achieve stunning, flat-field images with their fast refractor. With its premium optics, durable build, and simple integration into your imaging train, this flattener is a game-changer for capturing deep-sky objects in all their glory.\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eNOTE: This device is for photographic use only. It is NOT intended for visual use.\u003c\/span\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\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, extendable to lifetime\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c!----\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":41403619934281,"sku":"ES2FF","price":119.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/image_0792a453-a8be-4af6-9c35-f507b9b9706a.jpg?v=1716201191"},{"product_id":"astro-tech-0-8x-reducer-field-flattener-for-astro-tech-at80edl-doublet-apo-refractor","title":"Astro-Tech 0.8x Reducer\/Field Flattener for Astro-Tech AT80EDL Doublet APO Refractor","description":"\u003cp\u003eThe AT80EDLRF is the dedicated 0.8× reducer and field flattener for the Astro-Tech AT80EDL f\/7 doublet APO refractor. It does two things at once: it reduces the AT80EDL's 560mm f\/7 focal length to 448mm f\/5.6 — almost a full stop faster — and it flattens the field, delivering sharp, round stars from the center of the sensor to the corners. Without a flattener, every refractor produces a curved focal plane. Stars in the center are sharp, but stars toward the edges of the frame elongate as the curved image surface diverges from the flat sensor. The AT80EDLRF corrects that curvature and gives you a flat field across DSLR and dedicated astronomy camera sensors.\u003c\/p\u003e\n\n\u003cp\u003eAt f\/5.6, exposures are shorter, the field of view is wider, and the system is better matched to the fast download cycles of modern CMOS cameras. If the AT80EDL is your imaging platform, this is the reducer designed for it.\u003c\/p\u003e\n\n\u003ch3\u003eDesigned for the AT80EDL\u003c\/h3\u003e\n\n\u003cp\u003eThe AT80EDLRF is optically matched to the AT80EDL's doublet FCD-100 objective. It threads directly into the camera angle adjuster (CAA) on the AT80EDL's focuser drawtube via M63×1 threads on the scope side. The camera side has standard 48mm T-threads (M48×0.75) — DSLR and mirrorless cameras connect via a T-ring for your specific mount (sold separately), while dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring.\u003c\/p\u003e\n\n\u003cp\u003eWhile the AT80EDLRF may physically thread into other f\/7 refractors that use a 2.5\" focuser with M63 threads, its optical correction is designed around the AT80EDL's specific optical system. Performance with other scopes is not guaranteed.\u003c\/p\u003e\n\n\u003ch3\u003eBackfocus and Spacing\u003c\/h3\u003e\n\n\u003cp\u003eBackfocus is 55mm from the shoulder of the reducer to the image plane — the standard spacing for DSLR camera bodies with a T-ring. If you're using a dedicated astronomy camera, you may need spacers to achieve the correct 55mm distance, depending on your camera's backfocus requirement. The optical diagram provided on this page shows exact dimensions for calculating your imaging train spacing.\u003c\/p\u003e\n\n\u003ch3\u003eBuilt-In Filter Access\u003c\/h3\u003e\n\n\u003cp\u003eThe top section of the AT80EDLRF unscrews from the body, exposing 48mm filter threads on the underside of the removed cap. This lets you thread a standard 2\" (48mm) filter — narrowband, light pollution, UV\/IR cut — directly into the optical path without adding a separate filter drawer or changing your backfocus distance. The filter sits between the reducer optics and the telescope, in the correct position for the converging light cone.\u003c\/p\u003e\n\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eAT80EDLRF 0.8× reducer\/field flattener\u003c\/li\u003e\n  \u003cli\u003eSlip-on rubber dust cover (camera-side T-threads)\u003c\/li\u003e\n  \u003cli\u003eSlip-on dust cover (scope-side barrel)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e0.8× focal reduction — 560mm f\/7 becomes 448mm f\/5.6.\u003c\/strong\u003e Almost a full stop faster. Shorter exposures, wider field, and better matched to fast-readout CMOS cameras.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eField flattener corrects the AT80EDL's native field curvature.\u003c\/strong\u003e Round, sharp stars from center to corners across DSLR and dedicated astronomy camera sensors. No edge elongation.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDesigned specifically for the AT80EDL doublet APO.\u003c\/strong\u003e Optically matched to the AT80EDL's FCD-100 objective. Threads directly into the CAA via M63×1 threads.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFully multicoated optics.\u003c\/strong\u003e All air-to-glass surfaces carry broadband multicoatings for high light transmission and minimal scatter.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e48mm T-threads on the camera side.\u003c\/strong\u003e DSLR and mirrorless bodies connect via a T-ring (sold separately); dedicated CMOS\/CCD astronomy cameras attach directly — 48mm T-threads are standard on most.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e55mm backfocus — standard DSLR spacing.\u003c\/strong\u003e A T-ring and DSLR body typically land right at the correct distance. Astronomy cameras may need spacers.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBuilt-in 48mm filter access.\u003c\/strong\u003e Unscrew the top cap to thread a 2\" filter directly into the optical path. No separate filter drawer needed.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCompact and lightweight.\u003c\/strong\u003e 67mm diameter, 71.51mm long, 8 oz. Adds minimal weight and length to the imaging train.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\n\u003cp\u003e\u003cstrong\u003eDo I need this reducer, or can I use a generic field flattener?\u003c\/strong\u003e\u003cbr\u003e\nThe AT80EDLRF is designed to match the AT80EDL's specific optical curve. A generic flattener may not correct the field as well, and a generic reducer will almost certainly introduce coma or other aberrations that the matched reducer avoids. For best results with the AT80EDL, this is the one to use.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eCan I use this as a 1× flattener without the reduction?\u003c\/strong\u003e\u003cbr\u003e\nNo. The AT80EDLRF is a combined reducer\/flattener — it always reduces to 0.8×. If you want flat-field correction at the native 560mm f\/7 focal length, you would need a dedicated 1× field flattener (not currently offered for the AT80EDL in the Astro-Tech line).\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWill this work on my AT102EDL or AT125EDL?\u003c\/strong\u003e\u003cbr\u003e\nEach EDL scope has its own dedicated reducer\/flattener. The product manual PDF is shared across the AT80EDL, AT102EDL, and AT125EDL models, but the reducers themselves are separate SKUs matched to each scope's optics. Use the reducer designated for your specific scope.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eHow do I connect my camera?\u003c\/strong\u003e\u003cbr\u003e\nDSLR and mirrorless cameras connect via a T-ring for your specific mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring. The 55mm backfocus is measured from the reducer's shoulder to the sensor plane.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eCan I use filters with this reducer?\u003c\/strong\u003e\u003cbr\u003e\nYes. Unscrew the top cap of the reducer to access the built-in 48mm filter threads. Standard 2\" (48mm) threaded filters — narrowband, LP, UV\/IR cut — thread in directly. This keeps the filter in the correct optical path position without adding a separate filter drawer.\u003c\/p\u003e\n\n\u003ch3\u003eAccessories\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eT-ring for your camera mount (sold separately):\u003c\/strong\u003e Required for connecting DSLR and mirrorless cameras. Available for Canon EOS, Nikon F, Sony E, and other mounts. Dedicated CMOS\/CCD astronomy cameras connect directly via 48mm T-threads.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e48mm (2\") filters:\u003c\/strong\u003e Narrowband, light pollution, UV\/IR cut filters thread directly into the reducer's built-in filter holder.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\n\u003cp\u003eThe AT80EDLRF does what a matched reducer\/flattener should do: it makes the AT80EDL a faster, wider-field imaging system with a flat, corrected field — and it does it in a compact, 8-ounce package that threads directly into the focuser's camera angle adjuster. If you're imaging with the AT80EDL, this is the reducer designed for your scope. The 48mm T-threads connect to your camera, the built-in filter access keeps your optical train simple, and the 55mm backfocus is standard DSLR spacing. One piece, one connection, no guesswork on optical matching.\u003c\/p\u003e\n\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width:100%; border-collapse: collapse;\"\u003e\n  \u003ctbody\u003e\n    \u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAstro-Tech AT80EDLRF\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eType\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e0.8× Focal Reducer \/ Field Flattener\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eDesigned For\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAstro-Tech AT80EDL f\/7 Doublet APO Refractor\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eReduction Factor\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e0.8× (560mm f\/7 → 448mm f\/5.6)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCoatings\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFully multicoated\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eScope-Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM63×1 thread (threads into AT80EDL CAA)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera-Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e48mm T-threads (M48×0.75)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBackfocus\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e55mm (shoulder to image plane)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFilter Access\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eBuilt-in 48mm (2\") filter threads (unscrew top cap)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eOuter Diameter\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e67mm\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eLength\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e71.51mm\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWeight\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e8 oz\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWarranty\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e1 year\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":41563280179273,"sku":"AT80EDLRF","price":199.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/image_77f092f7-7870-4303-9f89-e6f56f5e2d65.jpg?v=1719596318"},{"product_id":"sky-watcher-evoguide-50ed-flattener","title":"Sky-Watcher EvoGuide 50ED Flattener","description":"\u003cp data-start=\"261\" data-end=\"343\" class=\"\"\u003e\u003cstrong data-start=\"261\" data-end=\"343\"\u003eSky-Watcher Field Flattener for EvoGuide 50DX – Bring Sharpness to the Corners\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp data-start=\"345\" data-end=\"670\" class=\"\"\u003eIf you're using the Sky-Watcher EvoGuide 50DX as a wide-field astrograph, the dedicated Field Flattener is a must-have accessory. This simple yet essential optical corrector transforms your compact ED refractor into a fully capable imaging telescope, delivering pinpoint stars from edge to edge—even on larger camera sensors.\u003c\/p\u003e\n\u003ch3 data-start=\"672\" data-end=\"706\" class=\"\"\u003eWhy You Need a Field Flattener\u003c\/h3\u003e\n\u003cp data-start=\"708\" data-end=\"1045\" class=\"\"\u003eRefractors—especially fast, short focal length models like the EvoGuide 50DX—are known for producing a curved field. While the center of your image may be razor-sharp, the edges can appear soft or stretched when paired with modern DSLR, mirrorless, or cooled CMOS cameras. This is especially noticeable with APS-C and full-frame sensors.\u003c\/p\u003e\n\u003cp data-start=\"1047\" data-end=\"1364\" class=\"\"\u003eThat’s where the field flattener comes in. It’s designed specifically for the EvoGuide 50DX’s optical system to correct this curvature and expand the usable field of view. With the flattener in place, you get a flat, distortion-free field that maintains stellar sharpness across the entire frame—no cropping required.\u003c\/p\u003e\n\u003ch3 data-start=\"1366\" data-end=\"1400\" class=\"\"\u003eOptimized for Astrophotography\u003c\/h3\u003e\n\u003cp data-start=\"1402\" data-end=\"1637\" class=\"\"\u003eThis field flattener provides a 1.0x magnification, meaning it won’t alter the focal length of the EvoGuide 50DX. You'll still enjoy the same fast f\/4.8 imaging speed and wide field, but now with improved performance across the sensor.\u003c\/p\u003e\n\u003cp data-start=\"1639\" data-end=\"1919\" class=\"\"\u003eIt’s engineered to deliver optimal correction at the standard 55mm backfocus, making it a seamless match for most DSLR and mirrorless camera setups using a T-ring. For dedicated astro cameras, the backfocus spacing remains just as easy to manage with standard spacers or adapters.\u003c\/p\u003e\n\u003ch3 data-start=\"1921\" data-end=\"1954\" class=\"\"\u003eThreaded for Easy Integration\u003c\/h3\u003e\n\u003cp data-start=\"1956\" data-end=\"2351\" class=\"\"\u003eSky-Watcher designed the flattener with versatility in mind. The rear threads are standard M48, allowing for wide T-ring connections that reduce vignetting—particularly important if you’re using a full-frame sensor. The front threads attach directly to the EvoGuide 50DX focuser, providing a secure, threaded connection that keeps your optical train aligned and stable throughout long exposures.\u003c\/p\u003e\n\u003cp data-start=\"2353\" data-end=\"2426\" class=\"\"\u003eNo wobble, no sag—just a tight, solid fit for better imaging consistency.\u003c\/p\u003e\n\u003ch3 data-start=\"2428\" data-end=\"2471\" class=\"\"\u003eCompact, Lightweight, and Purpose-Built\u003c\/h3\u003e\n\u003cp data-start=\"2473\" data-end=\"2787\" class=\"\"\u003eJust like the EvoGuide itself, the flattener is compact and lightweight, so it won’t upset your mount’s balance or overtax a portable tracking rig. It’s designed exclusively for the EvoGuide 50DX, ensuring the optical spacing and correction are precisely dialed in—something you won’t get from a generic flattener.\u003c\/p\u003e\n\u003cp data-start=\"2789\" data-end=\"3050\" class=\"\"\u003eIf you’re using the EvoGuide 50DX for imaging and haven’t added the field flattener yet, you’re leaving performance on the table. Whether you’re shooting large nebulae or rich star fields, this accessory helps you get the most out of your scope and your camera.\u003c\/p\u003e\n\u003chr data-start=\"3052\" data-end=\"3055\" class=\"\"\u003e\n\u003ch3 data-start=\"3057\" data-end=\"3072\" class=\"\"\u003eHighlights:\u003c\/h3\u003e\n\u003cul data-start=\"3074\" data-end=\"3465\"\u003e\n\u003cli data-start=\"3074\" data-end=\"3152\" class=\"\"\u003e\n\u003cp data-start=\"3076\" data-end=\"3152\" class=\"\"\u003e\u003cstrong data-start=\"3076\" data-end=\"3152\"\u003eFlattens the field of the EvoGuide 50DX for sharp stars across the frame\u003c\/strong\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3153\" data-end=\"3223\" class=\"\"\u003e\n\u003cp data-start=\"3155\" data-end=\"3223\" class=\"\"\u003e\u003cstrong data-start=\"3155\" data-end=\"3223\"\u003e1.0x design preserves original focal length and fast f\/4.8 speed\u003c\/strong\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3224\" data-end=\"3268\" class=\"\"\u003e\n\u003cp data-start=\"3226\" data-end=\"3268\" class=\"\"\u003e\u003cstrong data-start=\"3226\" data-end=\"3268\"\u003eIdeal for APS-C and full-frame sensors\u003c\/strong\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3269\" data-end=\"3322\" class=\"\"\u003e\n\u003cp data-start=\"3271\" data-end=\"3322\" class=\"\"\u003e\u003cstrong data-start=\"3271\" data-end=\"3322\"\u003eM48 threads for wide, secure camera connections\u003c\/strong\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3323\" data-end=\"3393\" class=\"\"\u003e\n\u003cp data-start=\"3325\" data-end=\"3393\" class=\"\"\u003e\u003cstrong data-start=\"3325\" data-end=\"3393\"\u003e55mm backfocus spacing for easy DSLR and astro cam compatibility\u003c\/strong\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3394\" data-end=\"3465\" class=\"\"\u003e\n\u003cp data-start=\"3396\" data-end=\"3465\" class=\"\"\u003e\u003cstrong data-start=\"3396\" data-end=\"3465\"\u003ePurpose-built for the EvoGuide 50DX—perfect fit and optical match\u003c\/strong\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"3467\" data-end=\"3748\" class=\"\"\u003eThis isn't just an upgrade—it's the final piece that turns your EvoGuide 50DX into a true wide-field astrograph. Whether you're a beginner wanting better stars or an advanced imager fine-tuning your setup, the Sky-Watcher Field Flattener makes a visible difference where it counts.\u003c\/p\u003e","brand":"Sky-Watcher","offers":[{"title":"Default Title","offer_id":41593635012681,"sku":"S20214","price":115.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/S20214_Evo50_Flat_web_1800x1800_a09c7201-4512-409d-aba3-ba1c4c5e6e36.webp?v=1723135807"},{"product_id":"astro-tech-1x-field-flattener-for-astro-tech-at80edt-triplet-apo-refractor","title":"Astro-Tech 1X Field Flattener For Astro-Tech AT80EDT Triplet APO Refractor","description":"\u003cp\u003eThe AT80EDT is one of our most popular grab-and-go imaging refractors — 80mm of FK-61 triplet glass at 480mm f\/6, compact enough for airline travel and light enough for small mounts, but sharp enough for serious deep-sky work. At f\/6, the field curves. Stars in the center are tight. Stars toward the edges stretch. That's not a flaw in the scope — it's what any uncorrected refractor does to a flat sensor. A dedicated field flattener fixes it.\u003c\/p\u003e\n\u003cp\u003eThe AT80EDTFF is a 1× flattener designed specifically for the AT80EDT. It doesn't reduce the focal length or change the focal ratio — you keep the full 480mm at f\/6. What it does is flatten the field so stars are round and sharp across your sensor. The AT80EDT delivers the light. The flattener makes sure that light lands correctly on the chip.\u003c\/p\u003e\n\u003ch3\u003eSensor Coverage — What to Expect\u003c\/h3\u003e\n\u003cp\u003eThe AT80EDTFF delivers excellent correction across APS-C sensors (roughly 22×15mm) and smaller — round, tight stars from center to edge. On full-frame sensors (36×24mm), you may see some residual curvature at the extreme corners. This is an 80mm scope at f\/6, and the corrected image circle has its limits. For most APS-C imaging — which is the sensor size most commonly paired with an 80mm refractor — the flattener does exactly what it needs to do. If you're planning to image full-frame with the AT80EDT, consider testing your specific camera to see if the corner performance meets your standards, or use cropping in processing.\u003c\/p\u003e\n\u003ch3\u003eWhy 1× Instead of a Reducer?\u003c\/h3\u003e\n\u003cp\u003eWe also make a 0.8× reducer\/field flattener for the AT80EDT. That drops the focal length to 384mm at f\/4.8 — faster exposures and a wider field, but a different image scale and a different set of targets that frame well. The 1× flattener is for imagers who want the AT80EDT's native 480mm focal length. At 480mm, mid-size targets — the Horsehead and Flame region, the Pleiades, the Orion Nebula complex, galaxy groups — have enough scale to show detail without being so large they clip the field. The flattener keeps the image scale and just fixes the field curvature.\u003c\/p\u003e\n\u003ch3\u003eConnection and Installation\u003c\/h3\u003e\n\u003cp\u003eThe scope side of the AT80EDTFF has an M63 threaded connection that threads directly onto the AT80EDT focuser drawtube — or onto the Camera Angle Adjuster if you're using the rotation feature. No barrel insert. No adapter. Just threads — secure, repeatable, and square to the optical axis every time you set up.\u003c\/p\u003e\n\u003cp\u003eThe camera side terminates in 48mm T-threads. DSLR and mirrorless bodies connect via a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring.\u003c\/p\u003e\n\u003cp\u003eBack focus is 55mm from the flattener's shoulder to the sensor. ZWO filter wheel + OAG + camera stacks are designed for 55mm and bolt together directly. A DSLR with a standard T-ring typically hits the spacing naturally. Dedicated cameras with different flange distances may need 48mm spacer rings to dial it in.\u003c\/p\u003e\n\u003ch3\u003eInline Filter Thread\u003c\/h3\u003e\n\u003cp\u003eThe top section of the flattener body unscrews, exposing a 2\" filter thread on the lower section. Thread in a light pollution, UHC, or narrowband filter without adding a separate filter drawer or filter wheel. For one-shot color camera setups with a single broadband or dual-narrowband filter, this keeps the imaging train short and the back focus math simple.\u003c\/p\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e1× dedicated field flattener — no focal reduction.\u003c\/strong\u003e Maintains the AT80EDT's native 480mm f\/6. Flattens the field for round stars across your sensor without changing image scale or field of view.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExcellent APS-C coverage.\u003c\/strong\u003e Corrects field curvature across APS-C (roughly 22×15mm) sensors and smaller with round stars from center to edge. Full-frame sensors may show some residual curvature at the extreme corners.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOptically matched to the AT80EDT.\u003c\/strong\u003e Designed for the AT80EDT's specific focal length and field curvature. Delivers better correction than generic flatteners because the optics are tuned to this scope.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM63 threaded scope-side connection.\u003c\/strong\u003e Threads directly to the AT80EDT focuser drawtube or Camera Angle Adjuster. No barrel insert, no adapter — secure, tilt-free positioning every session.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e48mm T-thread camera connection.\u003c\/strong\u003e DSLR and mirrorless bodies connect via a T-ring (sold separately); dedicated CMOS\/CCD astronomy cameras attach directly — 48mm T-threads are standard on most.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e55mm back focus.\u003c\/strong\u003e From the flattener shoulder to the sensor. Standard DSLR T-ring spacing typically hits this naturally. ZWO filter wheel + OAG + camera stacks are designed for 55mm.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e2\" inline filter thread.\u003c\/strong\u003e Unscrew the top section to expose a 2\" filter thread for inline filter use without a filter drawer.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFully multi-coated optics.\u003c\/strong\u003e Maximizes light transmission and minimizes internal reflections.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLightweight at 9.5 oz.\u003c\/strong\u003e Minimal impact on balance or focuser load.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProtective covers included.\u003c\/strong\u003e Threaded covers for both ends.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eObserving Tip\u003c\/h3\u003e\n\u003cp\u003eThe AT80EDT at 480mm f\/6 is a natural widefield imaging scope, and one of its strengths is that it frames larger targets well at a fast focal ratio. With the 1× flattener and an APS-C camera, you've got a flat, corrected field at 480mm — enough focal length for the Rosette Nebula, the Heart and Soul pair, the Lagoon and Trifid region, and similar mid-size targets to fill the frame with detail. If you're running a one-shot color camera with a single broadband or dual-narrowband filter, thread the filter into the flattener's 2\" thread and skip the filter drawer. Fewer connections, less tilt risk, simpler setup.\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eWhat's the difference between this and the 0.8× reducer\/flattener?\u003c\/strong\u003e\u003cbr\u003eThe AT80EDTFF is a 1× flattener — it corrects field curvature without changing focal length. You keep 480mm at f\/6. The 0.8× reducer\/flattener reduces to 384mm at f\/4.8 — faster exposures (56% more light per pixel), wider field, but different image scale. Choose the 1× for more image scale on smaller targets. Choose the 0.8× for wider fields and shorter exposures.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill this cover a full-frame sensor?\u003c\/strong\u003e\u003cbr\u003eThe flattener performs best with APS-C sensors and smaller. On full-frame chips, you may see some residual field curvature at the extreme corners. This is a function of the 80mm aperture — the corrected image circle is large enough for APS-C but reaches its limits on full frame. If you need guaranteed full-frame flat-field coverage, consider the AT115EDT or AT130EDT with their respective 1× flatteners.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDo I need a T-ring?\u003c\/strong\u003e\u003cbr\u003eIf you're using a DSLR or mirrorless camera, yes — you need a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use a filter wheel with this?\u003c\/strong\u003e\u003cbr\u003eYes. A ZWO filter wheel + OAG + camera stack is designed to hit 55mm back focus. Thread the flattener onto the scope, attach the filter wheel to the 48mm T-threads, and the system is at the correct spacing.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow critical is the 55mm back focus?\u003c\/strong\u003e\u003cbr\u003eVery. If the spacing from the flattener's shoulder to your sensor is off by more than a couple of millimeters, you'll see elongated stars toward the edges. M48 spacer rings in 1mm, 2mm, and 5mm increments let you dial it in. Measure once, mark your configuration, and it stays consistent.\u003c\/p\u003e\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\u003cp\u003eThe AT80EDT is a compact, travel-friendly imaging refractor with a loyal following. The AT80EDTFF gives it a flat field at the full 480mm f\/6 — round stars from center to edge across APS-C sensors, no compromise on focal length or image scale. If you're imaging with the AT80EDT and an APS-C camera, this is the flattener that was matched to your scope. Thread it on, set the spacing, and shoot.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse;\"\u003e\n\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAstro-Tech AT80EDTFF\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eOptical Function\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e1× field flattener (no focal reduction)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eTelescope Compatibility\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAstro-Tech AT80EDT\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFocal Length (with flattener)\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e480mm (unchanged)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFocal Ratio (with flattener)\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003ef\/6 (unchanged)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eSensor Coverage\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAPS-C (22×15mm) and smaller — full correction. Full frame may show residual corner curvature.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eTelescope Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM63 threaded (threads to focuser drawtube or Camera Angle Adjuster)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e48mm T-threads\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBack Focus\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e55mm (flattener shoulder to sensor)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFilter Thread\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e2\" (accessible by unscrewing top section)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCoatings\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFully multi-coated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWeight\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e9.5 oz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eIncluded Accessories\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eThreaded covers for both ends\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWarranty\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\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":41598549459017,"sku":"AT80EDTFF","price":199.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/M631xFlattenerAT80EDT_1-10855.jpg?v=1738261631"},{"product_id":"astro-tech-1x-field-flattener-for-astro-tech-at115edt-triplet-apo-refractor","title":"Astro-Tech 1X Field Flattener For Astro-Tech AT115EDT Triplet APO Refractor","description":"\u003cp\u003eThe AT115EDT has become one of the most popular imaging refractors we sell — 115mm of FK-61 triplet glass at 805mm f\/7, enough aperture and focal length to frame mid-size deep-sky targets with real detail. But like any refractor at f\/7, the field curves. Stars in the center are sharp. Stars at the edges stretch. That's not a flaw in the scope — it's what a curved focal plane does to a flat sensor. And it's exactly what a dedicated field flattener is designed to fix.\u003c\/p\u003e\n\u003cp\u003eThe AT115EDTFF is a 1× flattener built specifically for the AT115EDT. It doesn't reduce the focal length or change the focal ratio — you keep the full 805mm at f\/7. What it does is flatten the field so stars are round and sharp from center to edge across your entire sensor, including full-frame chips. The AT115EDT delivers the light. The flattener makes sure that light lands correctly on every part of your sensor.\u003c\/p\u003e\n\u003ch3\u003eWhy 1× Instead of a Reducer?\u003c\/h3\u003e\n\u003cp\u003eThe AT115EDT has a strong following among imagers who value its 805mm focal length for the image scale it provides. At 805mm, mid-size targets — the Rosette Nebula, the Crab Nebula, galaxy pairs, the Veil complex — have enough scale to show structural detail without being too large to frame. A 0.8× reducer would drop that to 644mm and widen the field, which is great for larger targets but changes the image scale you bought the scope for. The 1× flattener preserves everything about the AT115EDT's native optical performance and just fixes the field curvature.\u003c\/p\u003e\n\u003ch3\u003eConnection and Installation\u003c\/h3\u003e\n\u003cp\u003eThe scope side of the AT115EDTFF has an M63 threaded connection that threads directly onto the AT115EDT focuser drawtube — or onto the Camera Angle Adjuster if you're using the rotation feature for framing. No barrel insert. No adapter between the flattener and the focuser. Just threads — secure, repeatable, and square to the optical axis every session.\u003c\/p\u003e\n\u003cp\u003eThe camera side terminates in 48mm T-threads. DSLR and mirrorless bodies connect via a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring.\u003c\/p\u003e\n\u003cp\u003eBack focus is 55mm from the flattener's shoulder to the sensor. ZWO filter wheel + OAG + camera stacks are designed for 55mm and bolt together directly. A DSLR with a standard T-ring typically hits the spacing naturally. Dedicated cameras with different flange distances may need 48mm spacer rings to fine-tune.\u003c\/p\u003e\n\u003ch3\u003eInline Filter Thread\u003c\/h3\u003e\n\u003cp\u003eThe top section of the flattener body unscrews, exposing a 2\" filter thread on the lower section. Thread in a light pollution, UHC, or narrowband filter without a separate filter drawer or filter wheel. For one-shot color camera setups with a single broadband filter, this keeps the imaging train short and the back focus math simple.\u003c\/p\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e1× dedicated field flattener — no focal reduction.\u003c\/strong\u003e Maintains the AT115EDT's native 805mm f\/7. Flattens the field for round stars from center to edge without changing image scale or field of view.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFull-frame sensor coverage.\u003c\/strong\u003e Corrects field curvature across full-frame (36×24mm) sensors and smaller. Round stars in the corners, not just the center.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOptically matched to the AT115EDT.\u003c\/strong\u003e Designed for the AT115EDT's specific focal length and field curvature. Delivers better edge correction than generic flatteners because the optical correction is tuned to this scope.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM63 threaded scope-side connection.\u003c\/strong\u003e Threads directly to the AT115EDT focuser drawtube or Camera Angle Adjuster. No barrel insert, no adapter — secure, tilt-free positioning every session.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e48mm T-thread camera connection.\u003c\/strong\u003e DSLR and mirrorless bodies connect via a T-ring (sold separately); dedicated CMOS\/CCD astronomy cameras attach directly — 48mm T-threads are standard on most.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e55mm back focus.\u003c\/strong\u003e From the flattener shoulder to the sensor. Standard DSLR T-ring spacing typically hits this naturally. ZWO filter wheel + OAG + camera stacks are designed for 55mm.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e2\" inline filter thread.\u003c\/strong\u003e Unscrew the top section to expose a 2\" filter thread for inline filter use without a filter drawer.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFully multi-coated optics.\u003c\/strong\u003e Maximizes light transmission and minimizes internal reflections.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLightweight at 9.5 oz.\u003c\/strong\u003e Minimal impact on balance or focuser load.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProtective covers included.\u003c\/strong\u003e Thread on covers for both ends.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eObserving Tip\u003c\/h3\u003e\n\u003cp\u003eThe AT115EDT at 805mm f\/7 with the 1× flattener is a versatile imaging platform — long enough for galaxy detail and planetary nebula structure, wide enough for mid-size emission nebulae. If you're running a one-shot color camera with a dual-narrowband filter, thread the filter into the flattener's 2\" filter thread and skip the filter drawer entirely. Fewer connections mean less chance of tilt, less back focus to calculate, and a stiffer imaging train. Simpler is usually better.\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eWhat's the difference between this and a 0.8× reducer\/flattener?\u003c\/strong\u003e\u003cbr\u003eThe AT115EDTFF is a 1× flattener — it corrects field curvature without changing focal length. You keep 805mm at f\/7. A 0.8× reducer\/flattener would both flatten the field and reduce to ~644mm at ~f\/5.6 — faster exposures, wider field, but different image scale. Choose the 1× for full-resolution work on smaller targets. Choose the 0.8× for wider fields and shorter exposures.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill this work with other AT scopes?\u003c\/strong\u003e\u003cbr\u003eIt's designed for the AT115EDT. The optical correction is matched to the AT115EDT's specific focal length and field curvature. It may work with other refractors that use a 2\" focuser, but performance with other scopes is not guaranteed.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes this cover a full-frame sensor?\u003c\/strong\u003e\u003cbr\u003eYes. The corrected image circle covers full-frame 36×24mm sensors with flat, round stars from center to edge. Owners have confirmed flat fields on APS-C sensors with filter wheel and OAG stacks.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow does the M63 thread connection work?\u003c\/strong\u003e\u003cbr\u003eThe AT115EDT focuser drawtube has M63 threads on its back end. Remove the 2\" visual adapter and the flattener threads directly onto those exposed threads. If you're using the Camera Angle Adjuster, the flattener threads onto the adjuster instead. Either way, it's a direct threaded connection — no barrel, no adapter, no chance of tilt.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use a filter wheel with this?\u003c\/strong\u003e\u003cbr\u003eYes. A ZWO filter wheel + OAG + camera stack is designed to hit 55mm back focus. Thread the flattener onto the scope, attach the filter wheel to the 48mm T-threads, and the system is at the correct spacing.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow critical is the 55mm back focus?\u003c\/strong\u003e\u003cbr\u003eVery. If the spacing from the flattener's shoulder to your sensor is off by more than a couple of millimeters, you'll see elongated stars toward the edges. M48 spacer rings in 1mm, 2mm, and 5mm increments let you dial it in precisely.\u003c\/p\u003e\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\u003cp\u003eThe AT115EDT is already one of the best values in triplet imaging refractors. The AT115EDTFF turns it into a flat-field imaging system at the full 805mm f\/7 — round stars from center to corners, full-frame coverage, and no compromise on focal length or image scale. If you're imaging with the AT115EDT and want flat fields without reducing, this is the flattener that was matched to your scope.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse;\"\u003e\n\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAstro-Tech AT115EDTFF\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eOptical Function\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e1× field flattener (no focal reduction)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eTelescope Compatibility\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAstro-Tech AT115EDT\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFocal Length (with flattener)\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e805mm (unchanged)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFocal Ratio (with flattener)\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003ef\/7 (unchanged)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eSensor Coverage\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFull frame (36×24mm) and smaller\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eTelescope Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM63 threaded (threads to focuser drawtube or Camera Angle Adjuster)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e48mm T-threads\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBack Focus\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e55mm (flattener shoulder to sensor)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFilter Thread\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e2\" (accessible by unscrewing top section)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCoatings\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFully multi-coated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWeight\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e9.5 oz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eIncluded Accessories\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eThreaded covers for both ends\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWarranty\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\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":41598561091657,"sku":"AT115EDTFF","price":199.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/M631xFlattenerAT115EDT_1-10840.jpg?v=1738261689"},{"product_id":"astro-tech-1x-field-flattener-for-astro-tech-at130edt-triplet-apo-refractor","title":"Astro-Tech 1X Field Flattener For Astro-Tech AT130EDT Triplet APO Refractor","description":"\u003cp\u003eThe AT130EDT is one of the more capable imaging refractors in our lineup — 130mm of FK-61 triplet glass at 910mm f\/7, sharp enough to resolve detail that smaller scopes can't touch. But at f\/7, the field curves. Stars in the center are pinpoints. Stars at the edges start to elongate and blur. The scope isn't doing anything wrong — every uncorrected refractor does this. A flat sensor and a curved focal plane simply don't agree, and the longer the focal length, the more obvious the disagreement becomes.\u003c\/p\u003e\n\u003cp\u003eThe AT130EDTFF is a dedicated 1× field flattener that corrects this without changing anything else about the optical system. You keep the full 910mm focal length. You keep f\/7. You keep the image scale you chose this scope for. What changes is the field — it goes flat. Stars are round from center to edge across full-frame sensors. The optics the AT130EDT was designed to deliver now reach every corner of your chip.\u003c\/p\u003e\n\u003ch3\u003eWhy 1× Instead of a Reducer?\u003c\/h3\u003e\n\u003cp\u003eWe also make a 0.8× reducer\/field flattener for the AT130EDT. That drops the focal length to 728mm at f\/5.6 — faster exposures, wider field, but a different image scale. The 1× flattener is for imagers who specifically chose the AT130EDT for its 910mm focal length and don't want to give it up. If you're shooting smaller targets — planetary nebulae, galaxy details, tight emission structures — the full 910mm gives you the resolution and image scale to frame them properly. The flattener makes sure the field is flat while you use it.\u003c\/p\u003e\n\u003ch3\u003eConnection and Installation\u003c\/h3\u003e\n\u003cp\u003eThe scope side of the AT130EDTFF has an M63 threaded connection that threads directly onto the AT130EDT focuser drawtube — or onto the Camera Angle Adjuster if you're using the rotation feature. No barrel insert. No adapter. Just threads — secure, repeatable, and square to the optical axis every time you set up.\u003c\/p\u003e\n\u003cp\u003eThe camera side terminates in 48mm T-threads. DSLR and mirrorless bodies connect via a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring.\u003c\/p\u003e\n\u003cp\u003eBack focus is 55mm from the flattener's shoulder to the sensor. ZWO filter wheel + OAG + camera stacks are designed for 55mm and bolt together directly. A DSLR with a standard T-ring typically hits the spacing naturally. Dedicated cameras with different flange distances may need 48mm spacer rings to dial it in.\u003c\/p\u003e\n\u003ch3\u003eInline Filter Thread\u003c\/h3\u003e\n\u003cp\u003eThe top section of the flattener body unscrews, exposing a 2\" filter thread on the lower section. Thread in a light pollution, UHC, or narrowband filter without adding a separate filter drawer or filter wheel. For one-shot color camera setups with a single broadband or dual-narrowband filter, this keeps the imaging train short and the back focus math simple.\u003c\/p\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e1× dedicated field flattener — no focal reduction.\u003c\/strong\u003e Maintains the AT130EDT's native 910mm f\/7. Flattens the field for round stars from center to edge without changing image scale or field of view.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFull-frame sensor coverage.\u003c\/strong\u003e Corrects field curvature across full-frame (36×24mm) sensors and smaller. Round stars in the corners, not just the center.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOptically matched to the AT130EDT.\u003c\/strong\u003e Designed for the AT130EDT's specific focal length and field curvature. Delivers better edge correction than generic flatteners because the optical correction is tuned to this scope.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM63 threaded scope-side connection.\u003c\/strong\u003e Threads directly to the AT130EDT focuser drawtube or Camera Angle Adjuster. No barrel insert, no adapter — secure, tilt-free positioning every session.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e48mm T-thread camera connection.\u003c\/strong\u003e DSLR and mirrorless bodies connect via a T-ring (sold separately); dedicated CMOS\/CCD astronomy cameras attach directly — 48mm T-threads are standard on most.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e55mm back focus.\u003c\/strong\u003e From the flattener shoulder to the sensor. Standard DSLR T-ring spacing typically hits this naturally. ZWO filter wheel + OAG + camera stacks are designed for 55mm.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e2\" inline filter thread.\u003c\/strong\u003e Unscrew the top section to expose a 2\" filter thread for inline filter use without a filter drawer.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFully multi-coated optics.\u003c\/strong\u003e Maximizes light transmission and minimizes internal reflections.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLightweight at 9.5 oz.\u003c\/strong\u003e Minimal impact on balance or focuser load.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProtective covers included.\u003c\/strong\u003e Slip-on rubber covers for both ends.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eObserving Tip\u003c\/h3\u003e\n\u003cp\u003eAt 910mm, the AT130EDT with the 1× flattener is a natural match for smaller deep-sky targets — planetary nebulae like M57, M27, and NGC 7662 fill the frame beautifully at this focal length. Galaxy groups like the Leo Triplet or Markarian's Chain get enough image scale to show detail without being too tight to frame. If you find yourself cropping every image you take with the 0.8× reducer because the target is too small in the frame, the 1× flattener gives you the image scale you actually want — and the flat field to use it properly.\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eWhat's the difference between this and the 0.8× reducer\/flattener?\u003c\/strong\u003e\u003cbr\u003eThe AT130EDTFF is a 1× flattener — it corrects field curvature without changing focal length. You keep 910mm at f\/7. The 0.8× reducer\/flattener reduces to 728mm at f\/5.6 — faster exposures (56% more light per pixel), wider field, but different image scale. Choose the 1× for full-resolution imaging of smaller targets. Choose the 0.8× for wider fields and shorter exposures.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes this cover a full-frame sensor?\u003c\/strong\u003e\u003cbr\u003eYes. The corrected image circle covers full-frame 36×24mm sensors with flat, round stars from center to edge.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDo I need a T-ring?\u003c\/strong\u003e\u003cbr\u003eIf you're using a DSLR or mirrorless camera, yes — you need a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use a filter wheel with this?\u003c\/strong\u003e\u003cbr\u003eYes. A ZWO filter wheel + OAG + camera stack is designed to hit 55mm back focus. Thread the flattener onto the scope, attach the filter wheel to the 48mm T-threads, and the system is at the correct spacing.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow critical is the 55mm back focus?\u003c\/strong\u003e\u003cbr\u003eVery. If the spacing from the flattener's shoulder to your sensor is off by more than a couple of millimeters, you'll see elongated stars toward the edges. M48 spacer rings in 1mm, 2mm, and 5mm increments let you dial it in. Measure once, mark your configuration, and it stays consistent.\u003c\/p\u003e\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\u003cp\u003eThe AT130EDT at 910mm f\/7 has the focal length and resolution to frame smaller targets with real detail. The AT130EDTFF makes sure that resolution reaches every corner of your sensor. It threads on, stays square, flattens the field across full frame, and doesn't change your image scale. If you're imaging with the AT130EDT and you want flat fields at the full 910mm, this is the flattener that was designed for the job.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse;\"\u003e\n\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAstro-Tech AT130EDTFF\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eOptical Function\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e1× field flattener (no focal reduction)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eTelescope Compatibility\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAstro-Tech AT130EDT\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFocal Length (with flattener)\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e910mm (unchanged)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFocal Ratio (with flattener)\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003ef\/7 (unchanged)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eSensor Coverage\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFull frame (36×24mm) and smaller\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eTelescope Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM63 threaded (threads to focuser drawtube or Camera Angle Adjuster)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e48mm T-threads\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBack Focus\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e55mm (flattener shoulder to sensor)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFilter Thread\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e2\" (accessible by unscrewing top section)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCoatings\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFully multi-coated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWeight\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e9.5 oz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eIncluded Accessories\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSlip-on rubber covers for both ends\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWarranty\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\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":41598562304073,"sku":"AT130EDTFF","price":199.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/M631xFlattenerAT130EDT_1-10833.jpg?v=1738261730"},{"product_id":"astro-tech-1x-field-flattener-for-astro-tech-at90-triplet-apo-refractor","title":"Astro-Tech 1X Field Flattener For Astro-Tech AT90 Triplet APO Refractor","description":"\u003cp\u003eThe AT90EDX and AT90CFT are triplet APO refractors with essentially perfect on-axis optics — guaranteed .95 Strehl or higher. But point a camera at them without correction and the field curves. Stars in the center are sharp. Stars at the edges are not. The scope didn't do anything wrong — a flat sensor and a curved focal plane just don't agree. That's where a field flattener earns its place in the imaging train.\u003c\/p\u003e\n\u003cp\u003eThe AT90FF is a dedicated 1× flattener for the AT90 triplet series. It doesn't reduce the focal length or change the focal ratio — you keep the full 540mm at f\/6. What it does is flatten the field across the sensor so stars are round and sharp from center to edge, all the way to the corners of a full-frame chip. The AT90EDX delivers clean, color-free optics. The AT90FF delivers that quality across your entire sensor.\u003c\/p\u003e\n\u003ch3\u003eDedicated — Not Generic\u003c\/h3\u003e\n\u003cp\u003eThis flattener is optically matched to the AT90EDX and AT90CFT's specific focal length and field curvature. A generic 1× flattener designed for f\/5–f\/7 refractors in general will sort-of work, but it won't deliver the same edge-to-edge correction as a flattener that knows the exact optical system it's sitting behind. One reviewer put it simply: the images with the dedicated flattener were \"superb across the entire field,\" compared to \"okay\" with a generic unit. The difference is the matching.\u003c\/p\u003e\n\u003ch3\u003eConnection and Installation\u003c\/h3\u003e\n\u003cp\u003eThe scope side of the AT90FF has an M63 threaded connection that threads directly onto the AT90EDX or AT90CFT focuser drawtube — or onto the Camera Angle Adjuster if you're using the rotation feature for framing. No adapters between the flattener and the focuser. No barrel insert that can introduce tilt. Just threads — secure, repeatable, and square to the optical axis every time.\u003c\/p\u003e\n\u003cp\u003eThe camera side terminates in 48mm T-threads. DSLR and mirrorless bodies connect via a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring.\u003c\/p\u003e\n\u003cp\u003eBack focus is 55mm from the flattener's shoulder to the sensor. If you're using a ZWO camera with a ZWO filter wheel and off-axis guider, the ZWO system is designed so the combined stack hits 55mm automatically — just bolt the pieces together. A DSLR with a standard T-ring typically hits the spacing naturally. If you need to fine-tune, 48mm spacer rings in 1mm, 2mm, and 5mm increments let you dial it in precisely.\u003c\/p\u003e\n\u003ch3\u003eInline Filter Thread\u003c\/h3\u003e\n\u003cp\u003eThe top section of the flattener body unscrews from the main housing, exposing a 2\" filter thread on the lower section. This lets you thread a 2\" light pollution, UHC, or narrowband filter directly into the imaging train — inline, without a separate filter drawer or filter wheel adding back focus and potential tilt. If you're shooting from a light-polluted site with a one-shot color camera and a single broadband filter, this is a clean, simple way to get the filter into the path.\u003c\/p\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e1× dedicated field flattener — no focal reduction.\u003c\/strong\u003e Maintains the AT90's native 540mm focal length and f\/6 focal ratio. Flattens the field for round stars from center to edge without changing your image scale or field of view.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFull-frame sensor coverage.\u003c\/strong\u003e Corrects field curvature across full-frame (36×24mm) sensors and smaller. No vignetting on APS-C or full-frame chips. Stars are round in the corners, not just the center.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOptically matched to the AT90EDX and AT90CFT.\u003c\/strong\u003e Designed for the specific focal length and field curvature of the 90mm f\/6 triplet. Delivers better edge correction than generic flatteners because it's tuned to this optical system.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM63 threaded scope-side connection.\u003c\/strong\u003e Threads directly to the AT90 focuser drawtube or Camera Angle Adjuster. No barrel insert, no adapter — repeatable, tilt-free positioning every session.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e48mm T-thread camera connection.\u003c\/strong\u003e DSLR and mirrorless bodies connect via a T-ring (sold separately); dedicated CMOS\/CCD astronomy cameras attach directly — 48mm T-threads are standard on most.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e55mm back focus.\u003c\/strong\u003e From the flattener shoulder to the sensor. Standard DSLR T-ring spacing typically hits this naturally. ZWO filter wheel + OAG + camera stacks are designed for 55mm and bolt together directly.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e2\" inline filter thread.\u003c\/strong\u003e Unscrew the top section to expose a 2\" filter thread. Thread in a light pollution or narrowband filter without adding a filter drawer to your imaging train.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFully multi-coated optics.\u003c\/strong\u003e Maximizes light transmission and minimizes internal reflections for cleaner images.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLightweight at 9.5 oz.\u003c\/strong\u003e Minimal impact on balance. Won't overload the focuser or shift your imaging train's center of gravity.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProtective covers included.\u003c\/strong\u003e Slip-on rubber covers for both the 48mm T-thread end and the M63 scope-side threads.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eObserving Tip\u003c\/h3\u003e\n\u003cp\u003eIf you're switching from a DSLR to a dedicated astronomy camera, the back focus math changes even though the target is the same 55mm. A DSLR T-ring has a built-in flange distance that gets you close to 55mm with just the ring. A ZWO or QHY camera body is much shorter — which is why they're designed to stack with a filter wheel, off-axis guider, or spacer rings to make up the distance. Measure the sensor-to-flange distance of your camera (it's in the specs), subtract from 55mm, and fill the gap with spacers or accessories. Get this right once and mark your configuration — it stays right forever.\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eWhat's the difference between this and the 0.8× reducer\/flattener?\u003c\/strong\u003e\u003cbr\u003eThe AT90FF is a 1× flattener — it corrects field curvature without changing the focal length. You keep the full 540mm at f\/6. The 0.8× reducer\/flattener both flattens the field and reduces the focal length to 432mm at f\/4.8 — faster exposures, wider field, but different image scale. If you want to preserve the native focal length and image scale of the AT90, use the 1× flattener. If you want faster, wider imaging, use the 0.8× reducer.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes this cover a full-frame sensor?\u003c\/strong\u003e\u003cbr\u003eYes. The corrected image circle covers full-frame 36×24mm sensors. Owners have confirmed flat fields with no vignetting on the ASI2600MC Pro (APS-C sized sensor) and similar cameras, and the product description specifies full-frame coverage.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow does the M63 thread connection work?\u003c\/strong\u003e\u003cbr\u003eThe AT90EDX and AT90CFT focuser drawtube has M63 threads on its back end. You remove the 2\" visual adapter, and the flattener threads directly onto those exposed threads. If you're using the Camera Angle Adjuster, the flattener threads onto the adjuster instead. Either way, it's a direct threaded connection — no barrel, no adapter, no chance of tilt from a loose fit.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use a filter wheel with this?\u003c\/strong\u003e\u003cbr\u003eYes. A ZWO filter wheel plus off-axis guider plus camera stack is designed to hit 55mm back focus automatically. Thread the flattener onto the scope, attach the filter wheel to the 48mm T-threads, and the system is at the correct spacing. One CN owner runs an ASI294 + ZWO filter wheel + ZWO OAG on the same flattener without issues.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow critical is the 55mm back focus?\u003c\/strong\u003e\u003cbr\u003eVery. If the spacing from the flattener's shoulder to your sensor is off by more than a couple of millimeters, you'll see elongated stars toward the edges of the frame. M48 spacer rings in 1mm, 2mm, and 5mm increments let you dial it in. Measure once, mark your configuration, and it stays consistent.\u003c\/p\u003e\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\u003cp\u003eYou bought the AT90EDX or AT90CFT because the optics are exceptional. The AT90FF makes sure those optics translate to your sensor — all of your sensor, not just the center. It threads on, it stays square, it flattens the field from center to corners on a full-frame chip, and it doesn't change your focal length or focal ratio. If you're imaging with an AT90 and you want flat fields at the native 540mm f\/6, this is the flattener that was designed for the job.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse;\"\u003e\n\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAstro-Tech AT90FF\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eOptical Function\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e1× field flattener (no focal reduction)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eTelescope Compatibility\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAstro-Tech AT90EDX and AT90CFT\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFocal Length (with flattener)\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e540mm (unchanged)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFocal Ratio (with flattener)\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003ef\/6 (unchanged)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eSensor Coverage\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFull frame (36×24mm) and smaller\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eTelescope Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM63 threaded (threads to focuser drawtube or Camera Angle Adjuster)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera Side Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e48mm T-threads\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBack Focus\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e55mm (flattener shoulder to sensor)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFilter Thread\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e2\" (accessible by unscrewing top section)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCoatings\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFully multi-coated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWeight\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e9.5 oz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eIncluded Accessories\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eThreaded covers for both ends\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eWarranty\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\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":41598563778633,"sku":"AT90FF","price":199.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/M631xFlattenerAT90EDX_1-10849.jpg?v=1738261662"},{"product_id":"astro-tech-v3-1x-field-flattener-for-astro-tech-at115edt-triplet-apo-refractor-with-3-2-focuser","title":"Astro-Tech V3 1X Field Flattener For Astro-Tech AT115EDT Triplet APO Refractor with 3.2\" Focuser","description":"\u003cp\u003eThere's a specific kind of frustration that comes from imaging with a refractor and reviewing your frames the next morning. The core of M33 is exactly right — color balanced, detailed, pinpoint sharp in the center. But the stars at the edges are soft, stretched, pulling away from round. Your scope didn't fail you. Your focal plane did.\u003c\/p\u003e\n\u003cp\u003eThe AT115EDT is a triplet apo, and like all triplet refractors, it produces a curved focal plane. The better your seeing and the more you push your sensor to the edges, the more you'll notice it. The AT115EDTFFv3 corrects it — one piece of equipment, threaded directly into the M92 drawtube of your 3.2\" focuser — and your 805mm f\/7 system flattens out. Stars stay round from center to corner. Focal length stays exactly where you set it.\u003c\/p\u003e\n\u003cp\u003eThat last part matters. The 0.8× reducer\/flattener for the same scope corrects to 43.8mm of image circle and brings your system to 644mm f\/5.6. If you want more speed and a wider field, that's the right tool. But if 805mm f\/7 is where you want to be — if that's the plate scale you planned for, the focal length you chose for your targets — the 1× flattener is the piece that lets you stay there. As the manufacturer specifies, the corrected image circle reaches 60mm. A full-frame sensor diagonal is 43.3mm. Your corners are covered, and then some.\u003c\/p\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e1× magnification — 805mm f\/7 preserved.\u003c\/strong\u003e The flattener corrects field curvature without altering focal length or f\/ratio. The system you planned is the system you image with.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM92 male telescope connection.\u003c\/strong\u003e Threads directly into the AT115EDT's 3.2\" focuser drawtube — no adapters, no extension tubes, no guesswork.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e60mm corrected image circle (manufacturer-specified).\u003c\/strong\u003e Full-frame sensors fit well within the corrected zone. Coverage extends to medium-format for larger imaging systems using the M78 connection.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThree camera-side thread options.\u003c\/strong\u003e M78×1 female, M54×0.75 male, and M48×0.75 male. T-ring users connect at M48. Dedicated astronomy camera users and larger-format setups step up from there.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInternal 2\" filter thread.\u003c\/strong\u003e Unscrew the upper cell to reveal a standard 2\" filter thread. Keeps your imaging train short, eliminates a filter drawer, and puts a 2\" narrowband filter exactly where it belongs — permanently installed and out of the way.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e55mm back focus.\u003c\/strong\u003e Industry-standard spacing from flattener shoulder to sensor. Compatible with standard T-rings, spacer sets, and most astronomy camera adapters without modification.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFully multi-coated optics.\u003c\/strong\u003e Anti-reflection coatings on all air-to-glass surfaces. High contrast, minimal ghosting, no light scatter from uncritical surfaces.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThread-on end caps included.\u003c\/strong\u003e Both scope-side and camera-side caps protect your optics in storage and transport.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eUnder the Night Sky\u003c\/h3\u003e\n\u003cp\u003eAt 805mm focal length, the AT115EDT lives in a productive zone — long enough to show genuine galaxy structure, wide enough to take in large emission nebulae whole. With a flat field, you start to see what this scope was built to do.\u003c\/p\u003e\n\u003cp\u003ePoint it at the \u003cstrong\u003eOrion Nebula (M42)\u003c\/strong\u003e. At 805mm on a full-frame sensor, you get the full core of the Orion Molecular Cloud — the bright inner nebula, the fainter outer skirt, the Running Man (NGC 1977) tucked into the upper corner of the frame. Without a flattener, the stars at those corners drag and soften. With the AT115EDTFFv3 in the train, they stay tight. The Trapezium at center is pinpoint; the field stars at the edges are pinpoint too.\u003c\/p\u003e\n\u003cp\u003eFor galaxy season, the Bode\/Cigar pair — \u003cstrong\u003eM81 and M82\u003c\/strong\u003e — fit in a single full-frame field at this focal length, comfortably framed with room for the surrounding star field. M82's irregular dust structure and M81's spiral arms are both in play at 805mm. The flattener means you lose nothing to corner softness on a target this important.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eM33 (Triangulum Galaxy)\u003c\/strong\u003e is a classic test of a flat field: it spans nearly the full short axis of a full-frame sensor at 805mm, and its spiral arms reach out toward the corners of the frame. Any field curvature shows up as a soft outer ring. With the AT115EDTFFv3, that ring disappears. The outer HII regions in the spiral arms — NGC 604 among them — resolve cleanly across the full field.\u003c\/p\u003e\n\u003ch3\u003eObserving Tip\u003c\/h3\u003e\n\u003cp\u003eThe internal 2\" filter thread is more practical than it might look in the specs. Thread a 2\" dual narrowband filter into the upper cell and leave it there. The filter is protected, your imaging train stays as short as it was, and you have one fewer connection to re-seat when you're imaging after midnight and temperature has dropped. For Ha\/OIII work on emission nebulae — the Rosette, the Lagoon, the Veil — the internal filter position keeps flexure out of the equation.\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eWhy choose the 1× flattener instead of the 0.8× reducer\/flattener?\u003c\/strong\u003e\u003cbr\u003eIf you want to preserve your native focal length and f\/ratio, the 1× flattener is the right tool. It corrects field curvature without compressing the image. The 0.8× reducer\/flattener shortens your focal length from 805mm to 644mm and speeds up your system to f\/5.6 — useful if you want a wider field or faster exposures. The choice comes down to which focal length serves your targets. If 805mm is where you want to be, don't give it up.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes this work with the AT115EDT's 3.2\" focuser?\u003c\/strong\u003e\u003cbr\u003eYes — the AT115EDTFFv3 is designed specifically for the AT115EDT's 3.2\" focuser. The M92 male connection threads directly into the drawtube. No adapter rings required.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes the 1× flattener cover full-frame sensors?\u003c\/strong\u003e\u003cbr\u003eYes. The corrected image circle is 60mm as the manufacturer specifies — a full-frame sensor diagonal is approximately 43.3mm. Your sensor falls well within the corrected zone, with margin beyond full-frame for future-proofing.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use this with a DSLR or mirrorless camera?\u003c\/strong\u003e\u003cbr\u003eYes. Connect your DSLR or mirrorless camera using a standard 48mm T-ring (M48×0.75 thread, sold separately) at the camera-side connection. Dedicated astronomy CMOS cameras with 48mm T-thread connect directly — no additional T-ring needed. Cameras with 2\" nose pieces can also work with the appropriate adapter.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the required back focus distance?\u003c\/strong\u003e\u003cbr\u003e55mm from the shoulder of the flattener to your imaging sensor. This is the industry-standard spacing and is compatible with most T-rings, standard spacer sets, and astronomy camera adapters without modification. If you're using a dedicated camera, verify your adapter stack achieves this distance.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use 2\" filters with this flattener?\u003c\/strong\u003e\u003cbr\u003eYes — the upper cell of the AT115EDTFFv3 unscrews to reveal an internal 2\" filter thread. Any standard 2\" filter threads in directly. This eliminates the need for an external filter drawer and keeps your imaging train compact.\u003c\/p\u003e\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\u003cp\u003eA lot of astrophotographers choose the AT115EDT because it's the scope that doesn't require compromises — enough aperture to image seriously, enough portability to set up regularly, enough focal length to frame galaxies with real detail. The AT115EDTFFv3 is the piece that removes the one constraint the physics of a triplet imposes. Field curvature isn't a defect in the AT115EDT — it's inherent to the design of every triplet refractor. The flattener corrects it cleanly, and your 805mm f\/7 system delivers what you expected when you bought it: flat, sharp stars corner to corner, on every target you choose.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse; font-size: 0.95em;\"\u003e\n\u003ctbody\u003e\n\u003ctr style=\"background: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 8px 12px; font-weight: bold; width: 42%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 8px 12px;\"\u003eAT115EDTFFv3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #ffffff;\"\u003e\n\u003ctd style=\"padding: 8px 12px; font-weight: bold;\"\u003eCompatible Telescope\u003c\/td\u003e\n\u003ctd style=\"padding: 8px 12px;\"\u003eAstro-Tech AT115EDT with 3.2\" focuser\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 8px 12px; font-weight: bold;\"\u003eMagnification Factor\u003c\/td\u003e\n\u003ctd style=\"padding: 8px 12px;\"\u003e1.0× (no focal length change)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #ffffff;\"\u003e\n\u003ctd style=\"padding: 8px 12px; font-weight: bold;\"\u003eOriginal Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 8px 12px;\"\u003e805mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 8px 12px; font-weight: bold;\"\u003eFocal Ratio\u003c\/td\u003e\n\u003ctd style=\"padding: 8px 12px;\"\u003ef\/7 (unchanged)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #ffffff;\"\u003e\n\u003ctd style=\"padding: 8px 12px; font-weight: bold;\"\u003eCorrected Image Circle\u003c\/td\u003e\n\u003ctd style=\"padding: 8px 12px;\"\u003e60mm (manufacturer-specified)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 8px 12px; font-weight: bold;\"\u003eTelescope Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 8px 12px;\"\u003eM92 male\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #ffffff;\"\u003e\n\u003ctd style=\"padding: 8px 12px; font-weight: bold;\"\u003eCamera Threads\u003c\/td\u003e\n\u003ctd style=\"padding: 8px 12px;\"\u003eM78×1 female, M54×0.75 male, M48×0.75 male\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 8px 12px; font-weight: bold;\"\u003eBack Focus\u003c\/td\u003e\n\u003ctd style=\"padding: 8px 12px;\"\u003e55mm (flattener shoulder to sensor)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #ffffff;\"\u003e\n\u003ctd style=\"padding: 8px 12px; font-weight: bold;\"\u003eFilter Compatibility\u003c\/td\u003e\n\u003ctd style=\"padding: 8px 12px;\"\u003eStandard 2\" filters, internal thread (upper cell)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 8px 12px; font-weight: bold;\"\u003eOptical Coatings\u003c\/td\u003e\n\u003ctd style=\"padding: 8px 12px;\"\u003eFully multi-coated, anti-reflection\u003c\/td\u003e\n\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":41967931490377,"sku":"AT115EDTFFV3","price":299.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/M921xFlattenerAT115EDT_1-10826.jpg?v=1738261812"},{"product_id":"astro-tech-v3-1x-field-flattener-for-astro-tech-at130-triplet-apo-refractor-with-3-2-focuser","title":"Astro-Tech V3 1X Field Flattener For Astro-Tech AT130 Triplet APO Refractor with 3.2\" Focuser","description":"\u003ch2\u003eAstro-Tech AT130EDTFFv3 1× Field Flattener\u003c\/h2\u003e\n\u003cp\u003eSometimes you don't want to speed up your system. You want to sharpen it. The AT130EDT is a 910mm f\/7 triplet — deliberately so. That focal length is what you chose, and it's doing the work you need it to do. The problem isn't the speed or the reach. It's the field curvature that comes with any triplet design: stars that are tight in the center going soft at the edges of a camera sensor. The AT130EDTFFv3 addresses exactly that — and nothing else. Your focal length stays at 910mm. Your f\/ratio stays at f\/7. What changes is the field: flat, corrected, sharp stars across the field.\u003c\/p\u003e\n\u003cp\u003eThe 0.8× reducer\/flattener for the same scope corrects to 43.8mm — already more than enough for full-frame coverage. The 1× flattener corrects to 60mm, as the manufacturer specifies. That's medium-format territory. Most full-frame sensors (diagonal ~43.3mm) land well inside that circle, which means the correction holds with serious headroom to spare. If you're shooting a Sony A7, a Canon R5, a ZWO ASI2600, or any full-frame imaging camera — the corners are covered.\u003c\/p\u003e\n\u003cp\u003eThe flattener threads directly into the M92 drawtube of the AT130EDT's 3.2\" focuser or the AT130EDX's 3.7\" focuser — no adapters, no intermediate hardware. Three camera-side thread options are built in: M78×1 female, M54×0.75 male, and M48×0.75 male. Dedicated CMOS and CCD astronomy cameras connect directly via M54 or M48 — no T-ring needed. DSLR and mirrorless cameras connect via a T-ring for your specific mount (sold separately). The standard 55mm back focus from the flattener shoulder to your sensor is compatible with most T-rings, spacers, and off-axis guiders without custom hardware.\u003c\/p\u003e\n\u003cp\u003eThe top optical cell unscrews to reveal an internal 2\" filter thread. Narrowband, light pollution rejection, or broadband filters thread directly into the optical path — no filter drawer required. The imaging train stays compact. Fully multi-coated throughout with broadband anti-reflection coatings. Thread-on dust caps for both ends are included.\u003c\/p\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003e1× magnification — native focal length preserved.\u003c\/strong\u003e 910mm f\/7 stays 910mm f\/7. You chose that focal length for your targets. This flattener doesn't negotiate it away — it just makes the field flat.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e60mm corrected image circle (manufacturer-specified).\u003c\/strong\u003e The largest corrected field in the AT130EDT flattener family. Full-frame sensors land inside this circle with room to spare. Medium-format sensors and custom large-format setups using the M78 connection can access the full 60mm field.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eM92 scope-side connection.\u003c\/strong\u003e Threads directly into the AT130EDT 3.2\" focuser drawtube and AT130EDX 3.7\" focuser drawtube. Purpose-matched to the optical geometry of the 130mm Astro-Tech triplets — not a generic flattener that happens to thread in.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eThree camera-side thread options.\u003c\/strong\u003e M78×1 female, M54×0.75 male, and M48×0.75 male. Dedicated CMOS and CCD astronomy cameras connect directly via their back plate threads. DSLR and mirrorless cameras use a T-ring (sold separately) plus step adapter to M48.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eInternal 2\" filter threads.\u003c\/strong\u003e Top optical cell unscrews to accept standard 2\" astronomy filters. Narrowband, broadband, and light pollution filters all fit. No filter drawer needed.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFully multi-coated, broadband AR coatings.\u003c\/strong\u003e Maximum light transmission, controlled internal reflections. Important for narrowband imaging where any stray light in the optical path shows up in the data.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e55mm back focus.\u003c\/strong\u003e Industry-standard spacing from flattener shoulder to sensor. Compatible with most camera and adapter combinations without custom spacers. Note: adding a filter wheel or other accessories between flattener and camera will require spacing adjustment to maintain 55mm total.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIncludes thread-on dust caps.\u003c\/strong\u003e Scope-side and camera-side. Protect the coated surfaces between sessions.\u003c\/p\u003e\n\u003ch3\u003eUnder the Night Sky\u003c\/h3\u003e\n\u003cp\u003eAt 910mm and f\/7, the AT130EDT frames targets that benefit from genuine reach. With a flat field and a full-frame sensor, the field of view runs approximately 2.3° × 1.5° on APS-C, or 3.8° × 2.5° on full-frame — precise enough for demanding targets without being so narrow that setup becomes a guessing game. M57 (Ring Nebula) shows its central structure clearly in 5-minute subs. M27 (Dumbbell Nebula) fills the frame with detail in the outer envelope. The Crab Nebula (M1) shows filamentary structure in extended narrowband exposure. For galaxy work, M81 and M82 frame together on APS-C with both showing detail — dust lanes in M81, the irregular starburst structure in M82. Stephan's Quintet fits on full-frame with room to include NGC 7317 for context.\u003c\/p\u003e\n\u003cp\u003eThe 60mm image circle means the stars at the extreme corners of your sensor are flat and round — not just within the central APS-C crop, but across the full frame. That matters when you're stacking 40 or 50 subs and the corners are part of your composition. It also matters if you upgrade sensors later — the correction will hold.\u003c\/p\u003e\n\u003ch3\u003eCommunity Says\u003c\/h3\u003e\n\u003cp\u003e\"This is an excellent flattener when coupled with my Astro-Tech AT130EDT. The flattener gives round stars in all corners of images taken with an APS-C OSC sensor. There is just the slightest hit of some CA which is easily handled in post-processing. Another excellent purchase from Astronomics!\" — \u003cstrong\u003eMichael H.\u003c\/strong\u003e ★★★★★\u003c\/p\u003e\n\u003ch3\u003eObserving Tip\u003c\/h3\u003e\n\u003cp\u003eFor first light with the AT130EDTFFv3, aim at a rich star field — the Double Cluster in Perseus or the area around M45 works well. Check your corner stars at full resolution in your stacking software. Round and tight means your 55mm back focus is correct. If you see stars radiating outward from the center, your sensor is too close to the flattener — add spacing. If stars are bowing inward toward the center, your sensor is too far — remove spacing. Get this right once on a simple target, and every subsequent session is ready to go from first light.\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eShould I get the 1× flattener or the 0.8× reducer?\u003c\/strong\u003e\u003cbr\u003eDepends on what you want. The 0.8× reducer shortens the focal length from 910mm to 728mm and speeds up from f\/7 to f\/5.6 — useful if you want a wider field, shorter exposures, or larger targets that need more sky. The 1× flattener keeps your full 910mm f\/7 and adds a larger 60mm corrected image circle. If you like your current focal length and want flat corners, get the flattener. If you want more versatility or a faster system, get the reducer. Some imagers own both.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes the 1× flattener cover full-frame sensors?\u003c\/strong\u003e\u003cbr\u003eYes, with significant margin. The corrected image circle is 60mm as the manufacturer specifies — a full-frame sensor diagonal is ~43.3mm. Your corners are well within the corrected zone. The 60mm circle also accommodates future sensor upgrades without losing corner correction.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDo I need a T-ring to connect my camera?\u003c\/strong\u003e\u003cbr\u003eDedicated CMOS and CCD astronomy cameras (ZWO, QHY, Player One, and similar) typically connect directly via M54 or M48 threads on their back plates — no T-ring needed. DSLR and mirrorless cameras connect via a T-ring for your specific mount (sold separately) plus a step adapter to M48.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes this work with the AT130EDT Version I (2.5\" focuser)?\u003c\/strong\u003e\u003cbr\u003eNo. The AT130EDTFFv3 requires the M92 drawtube of the AT130EDT Version II (3.2\" focuser) or the AT130EDX (3.7\" focuser). It is not compatible with the earlier 2.5\" focuser drawtube.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat's the correct back focus, and how do I dial it in?\u003c\/strong\u003e\u003cbr\u003e55mm from the shoulder of the flattener to your sensor. Most T-rings and dedicated camera back plates land close to this naturally. If you add accessories between the flattener and camera — a filter wheel, off-axis guider, or spacers — account for their depth to keep the total at 55mm. Small adjustments of 1–2mm can make a visible difference at the corners. The included PDF tech sheet has star pattern diagrams that show you how to read the direction you need to adjust.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use this flattener with the AT115EDT?\u003c\/strong\u003e\u003cbr\u003eNo. Use the AT115EDTRFv3 or the equivalent 1× flattener matched to the AT115EDT. Each flattener is designed for the specific optical geometry of its scope — using the AT130EDT version on the AT115EDT will not produce correct field correction.\u003c\/p\u003e\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\u003cp\u003eThe imager who buys this already knows what 910mm f\/7 gets them. They're not looking for more sky — they're looking for sharper sky. The AT130EDT is a triplet that delivers excellent color correction and a long, precise focal length. The field curvature is the one thing it can't solve on its own. The AT130EDTFFv3 solves it, across a 60mm corrected circle that no sensor you're likely to own will outgrow. If you've been getting good data from the center of your frame and watching the corners drift soft — this is the fix. One piece of glass, correctly spaced, and the scope you already own starts performing the way it was always capable of performing.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse;\"\u003e\n\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAT130EDTFFv3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCompatible Telescopes\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAT130EDT (3.2\" focuser), AT130EDX (3.7\" focuser)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eMagnification Factor\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e1.0× (no focal reduction)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eNative Focal Length Preserved\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e910mm f\/7 (AT130EDT\/EDX)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCorrected Image Circle\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e60mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eScope Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM92 male\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera Connections\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM78×1 female, M54×0.75 male, M48×0.75 male\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBack Focus\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e55mm (flattener shoulder to sensor)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFilter Threads\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eInternal 2\" (48mm) beneath top optical cell\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCoatings\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFully multi-coated, broadband AR\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":41967958720585,"sku":"AT130EDTFFV3","price":299.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/M921xFieldFlattenerAT130EDT_1-10807.jpg?v=1738261794"},{"product_id":"astro-tech-v3-0-8x-reducer-field-flattener-for-astro-tech-at115edt-triplet-apo-refractor-with-3-2-focuser-copy","title":"Astro-Tech V3 0.8x Reducer\/Field Flattener For Astro-Tech AT115EDT Triplet APO Refractor with 3.2\" Focuser","description":"\u003ch2\u003eAstro-Tech AT115EDTRFv3 0.8× Reducer\/Field Flattener\u003c\/h2\u003e\n\u003cp\u003eThe AT115EDT is a triplet apochromat — three air-spaced elements that bring color under tight control and deliver sharp, high-contrast images at f\/7. What it doesn't do on its own is flatten the field for imaging. At 805mm, the field curvature is gentle enough to be invisible visually, but a camera sensor at the focal plane sees it in the corners: stars that are sharp in the center going slightly soft toward the edges. The AT115EDTRFv3 corrects that, and while it's at it, reduces the focal length to 644mm at f\/5.6 — roughly 36% faster, with a wider field of view. One element, threaded in, and the scope changes character in the best possible way.\u003c\/p\u003e\n\u003cp\u003eThis is the V3 — the third generation of a reducer\/flattener matched specifically to the optical geometry of the AT115EDT. It threads directly into the M92 drawtube of the 3.2\" focuser with no intermediate adapters. Set your camera spacing to 55mm from the reducer shoulder to your sensor, and the triplet becomes a 644mm f\/5.6 astrograph with a corrected 43.8mm image circle.\u003c\/p\u003e\n\u003cp\u003eThe camera side offers three direct threading options: M78×1 female, M54×0.75 male, and M48×0.75 male. Dedicated CMOS and CCD astronomy cameras connect directly via whichever thread matches their back plate — no T-ring needed. DSLR and mirrorless cameras connect via a T-ring for your specific mount, combined with a step adapter to M48. The three-thread design handles the majority of imaging setups without additional hardware.\u003c\/p\u003e\n\u003cp\u003eUnscrew the top knurled ring and you'll find internal 2\" filter threads. Narrowband, broadband, or light pollution rejection filters thread in directly — no filter drawer, no extra back focus to manage. The filter lives in the reducer, rotates with the camera, and keeps the imaging train as compact as possible. Fully multi-coated with broadband anti-reflection coatings on all surfaces. Thread-on dust caps for both ends are included.\u003c\/p\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003e0.8× focal reduction.\u003c\/strong\u003e 805mm f\/7 becomes 644mm f\/5.6 — about 36% faster. That's the difference between a 10-minute sub and a 6.5-minute sub for equivalent signal. On a night with three good hours, those saved minutes add up to real data.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eField flattener integrated.\u003c\/strong\u003e The AT115EDT is a triplet with native field curvature. The V3 corrects that curvature across a full 43.8mm image circle — the same full-frame coverage as the AT130EDT version, sharp from center to corner.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eM92 scope-side connection.\u003c\/strong\u003e Threads directly into the AT115EDT's 3.2\" focuser drawtube. No adapters, no shimming, no backfocus arithmetic at the scope end.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eThree camera-side thread options.\u003c\/strong\u003e M78×1 female, M54×0.75 male, and M48×0.75 male. Dedicated CMOS and CCD cameras connect directly. DSLR and mirrorless cameras connect via a T-ring plus step adapter to M48 (T-ring sold separately).\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eInternal 2\" filter threads.\u003c\/strong\u003e Top knurled ring unscrews to accept standard 2\" astronomy filters — narrowband (Hα, OIII, SII), broadband LRGB, and light pollution filters all fit. No external filter drawer required.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFully multi-coated optics.\u003c\/strong\u003e Broadband anti-reflection coatings throughout. Maximum light throughput and controlled internal reflections — important when imaging faint emission nebulae with narrowband filters.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e55mm back focus.\u003c\/strong\u003e Standard spacing from reducer shoulder to image plane. Works with most camera and adapter combinations without custom spacers.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIncludes thread-on dust caps.\u003c\/strong\u003e Scope-side and camera-side covers protect coated surfaces when the reducer is off the telescope.\u003c\/p\u003e\n\u003ch3\u003eUnder the Night Sky\u003c\/h3\u003e\n\u003cp\u003eAt 644mm and f\/5.6, the AT115EDT reaches targets it couldn't quite frame comfortably at native focal length. The Heart Nebula (IC 1805) — about 2.5° across — fits on an APS-C sensor with room for context. The Rosette Nebula (NGC 2237), just over 1.3°, sits squarely in the frame. The North America Nebula (NGC 7000) fills the sensor edge-to-edge with its characteristic landmass shape. M42 and the full Orion complex, including the faint outer nebulosity, land at an ideal scale for wide single-frame captures.\u003c\/p\u003e\n\u003cp\u003eFor galaxy imaging, 644mm is effective at resolving structure in nearby groups. M81 and M82 frame together on APS-C with both galaxies showing detail. The Virgo Cluster core — M84, M86, and the surrounding Markarian's Chain — fits in a single frame with enough angular separation to read each member individually. The 115mm aperture gathers enough light to show dust lane hints in M82 in a reasonable number of subs.\u003c\/p\u003e\n\u003cp\u003eAt f\/5.6, narrowband imaging becomes genuinely efficient. An hour of Hα data on the Elephant Trunk Nebula (IC 1396) pulls up the pillar structure clearly. The Cygnus Wall section of NGC 7000 shows sharp emission edges in 5-minute subs. This is the kind of result the AT115EDT was capable of all along — the reducer\/flattener just removes the friction.\u003c\/p\u003e\n\u003ch3\u003eCommunity Says\u003c\/h3\u003e\n\u003cp\u003e\"I didn't know much about this new v3 except that it was supposed to be bigger. This thing is bigger and it's amazing. The image circle from this is bigger than anything I have. It covers my full frame dslr 100% and works great with my asi2600mc duo. I love that it has the 2 inch filter holder built in. Images are flat, the scope is faster (f\/5.6 when using this reducer). It's a great product.\" — \u003cstrong\u003eClayton O.\u003c\/strong\u003e, February 2025 ★★★★★\u003c\/p\u003e\n\u003cp\u003e\"Cloudy skies are keeping me from using it as much as I would like so far but it seems to work great. Thanks for all the help putting it together!\" — \u003cstrong\u003eFred G.\u003c\/strong\u003e, May 2025 ★★★★★\u003c\/p\u003e\n\u003ch3\u003eObserving Tip\u003c\/h3\u003e\n\u003cp\u003eFor your first light with the AT115EDTRFv3, aim at a field with a mix of stellar magnitudes — the Double Cluster in Perseus works well. Check the corner stars at full resolution. If they're round and tight, your 55mm back focus spacing is dialed in and you're ready to go to work on faint targets. If you see elongated stars or coma patterns in the corners, adjust your spacing by 1–2mm at a time until the field flattens. Getting this right once means every session after that is plug-and-shoot.\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eDoes this work with the AT115EDT Version I (2.5\" focuser)?\u003c\/strong\u003e\u003cbr\u003eNo. The AT115EDTRFv3 requires the M92 drawtube of the AT115EDT with the 3.2\" focuser. It is not compatible with the earlier 2.5\" focuser. If you're not sure which version you have, measure the focuser opening — Version II units have the wider 3.2\" aperture and the M92 drawtube.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes it cover full-frame sensors?\u003c\/strong\u003e\u003cbr\u003eYes. The corrected image circle is 43.8mm, which covers the full 35mm full-frame sensor format (diagonal ~43.3mm) edge to edge. Stars are sharp and flat across the entire frame.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDo I need a T-ring to connect my camera?\u003c\/strong\u003e\u003cbr\u003eDedicated CMOS and CCD astronomy cameras (ZWO, QHY, Player One, and similar) typically have M54 or M48 back plates and connect directly — no T-ring needed. DSLR and mirrorless cameras connect via a T-ring for your specific lens mount plus a step adapter to M48. T-rings are sold separately.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat filters fit in the internal threads?\u003c\/strong\u003e\u003cbr\u003eStandard 2\" astronomy filters with 48mm filter threads. This includes narrowband filters (Hα, OIII, SII), broadband LRGB sets, and light pollution rejection filters. If a filter fits a standard 2\" filter wheel slot, it will thread into the AT115EDTRFv3.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use this with the AT130EDT?\u003c\/strong\u003e\u003cbr\u003eNo — use the AT130EDTRFv3 for the AT130EDT and AT130EDX. Each reducer\/flattener is matched to the specific focal length and field curvature of its scope. Using the wrong version will produce incorrect field correction.\u003c\/p\u003e\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\u003cp\u003eIf you own the AT115EDT and you're imaging, this is the most efficient upgrade available to you. No new scope, no new mount, no new camera — just one precision element threaded into the focuser drawtube, and your 805mm f\/7 triplet becomes a 644mm f\/5.6 astrograph with corrected field corners. The targets that were slightly too large to frame at native focal length — the Heart Nebula, the Rosette, the great Cygnus emission fields — move into range. The exposures run a third shorter. And the field flattener that the AT115EDT optical design never included, because triplets don't, gets quietly supplied. It's a logical completion of a scope that was already doing most things right.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse;\"\u003e\n\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAT115EDTRFv3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCompatible Telescope\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAstro-Tech AT115EDT (3.2\" focuser)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFocal Reduction\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e0.8×\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eOriginal Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e805mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eReduced Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e644mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Ratio\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003ef\/5.6 (from f\/7)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCorrected Image Circle\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e43.8mm (full-frame)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eScope Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM92 male\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera Connections\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM78×1 female, M54×0.75 male, M48×0.75 male\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBack Focus\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e55mm (reducer shoulder to sensor)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFilter Threads\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eInternal 2\" (48mm) in upper optical element\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCoatings\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFully multi-coated, broadband AR\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":41967960784969,"sku":"AT115EDTRFV3","price":299.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/M920.8xReducerFlattenerAT115EDT_1-10819.jpg?v=1738261764"},{"product_id":"astro-tech-v3-0-8x-reducer-field-flattener-for-astro-tech-at130edt-or-at130edx-triplet-apo-refractor-with-3-2-focuser","title":"Astro-Tech V3 0.8x Reducer\/Field Flattener For Astro-Tech AT130EDT or AT130EDX Triplet APO Refractor with 3.2\" Focuser","description":"\u003ch2\u003eAstro-Tech AT130EDTRFv3 0.8× Reducer\/Field Flattener\u003c\/h2\u003e\n\u003cp\u003eA triplet apochromat like the AT130EDT does one thing very well: it controls color. Three elements, air-spaced, designed to bring red, green, and blue to a common focus without the fringing that follows lesser glass. What a triplet doesn't do natively is flatten the field for imaging. At 910mm and f\/7, the field curvature is there — not dramatic, but enough to soften the corners of a camera sensor. The AT130EDTRFv3 solves both problems at once: it flattens the field and reduces the focal length to 728mm at f\/5.6, giving you sharper corners, a wider field of view, and roughly 36% shorter exposures — in a single threaded element.\u003c\/p\u003e\n\u003cp\u003eThis is the V3, the third generation of a reducer\/flattener we've been refining specifically for the AT130EDT optical system. It threads directly into the M92 drawtube of the AT130EDT's 3.2\" focuser — no intermediate adapters, no backfocus arithmetic. Thread it in, set your camera spacing to 55mm from the reducer shoulder to your sensor, and the 910mm f\/7 triplet becomes a 728mm f\/5.6 wide-field astrograph with a corrected 43.8mm image circle. For full-frame sensors, that means flat, sharp stars edge to edge. For APS-C, the correction is complete well before you reach the crop boundary.\u003c\/p\u003e\n\u003cp\u003eThe camera side of the AT130EDTRFv3 offers three direct threading options: M78×1 female, M54×0.75 male, and M48×0.75 male. Dedicated CMOS and CCD astronomy cameras connect directly via whichever thread matches their back plate — no T-ring needed for most. DSLR and mirrorless cameras connect via a T-ring for your specific mount, combined with a step adapter to M48. The three-thread design covers the majority of imaging setups without additional hardware.\u003c\/p\u003e\n\u003cp\u003eThe upper knurled ring unscrews to reveal internal 2\" filter threads. That means narrowband, light pollution rejection, or broadband filters can live directly in the reducer — no external filter drawer required. The optical path stays compact, and your filter rotates with the camera rather than sitting between the scope and reducer. It's the kind of detail that matters when you're trying to simplify a complex imaging train.\u003c\/p\u003e\n\u003cp\u003eFully multi-coated with broadband anti-reflection coatings throughout. Thread-on dust caps are included for both ends. Back focus is 55mm from the reducer shoulder to the image plane — standard spacing that works with most camera and adapter combinations. Also compatible with the AT130EDX with its 3.7\" focuser, using the same M92 scope-side connection.\u003c\/p\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003e0.8× focal reduction.\u003c\/strong\u003e 910mm f\/7 becomes 728mm f\/5.6. Exposures run approximately 36% shorter for equivalent signal. That's a meaningful gain on narrowband targets or any night where time is limited.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eField flattener integrated.\u003c\/strong\u003e The AT130EDT is a triplet — it produces excellent color correction but native field curvature that shows at the corners. The V3 corrects that curvature across a full 43.8mm image circle. No separate flattener required; no guesswork about which flattener pairs correctly with which scope.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eM92 scope-side connection.\u003c\/strong\u003e Threads directly into the AT130EDT 3.2\" focuser drawtube and AT130EDX 3.7\" focuser drawtube. No adapters, no shimming.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eThree camera-side thread options.\u003c\/strong\u003e M78×1 female, M54×0.75 male, and M48×0.75 male. Dedicated CMOS and CCD astronomy cameras connect directly — most have M54 or M48 back plates built in. DSLR and mirrorless cameras connect via a T-ring plus step adapter to M48.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eInternal 2\" filter threads.\u003c\/strong\u003e The upper optical element unscrews to accept standard 2\" astronomy filters. Narrowband, broadband, and light pollution filters all fit. No external filter drawer needed.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFully multi-coated optics.\u003c\/strong\u003e Broadband anti-reflection coatings on all surfaces. Contrast is preserved and internal ghosting is controlled across the full wavelength range — important for narrowband imaging where stray light shows up.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e55mm back focus.\u003c\/strong\u003e Standard spacing from reducer shoulder to image plane. Compatible with most camera-and-adapter combinations without custom spacers.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIncludes thread-on dust caps.\u003c\/strong\u003e One for the scope side, one for the camera side. Protect the coated surfaces between sessions.\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eDoes this work with the AT130EDT Version I (2.5\" focuser)?\u003c\/strong\u003e\u003cbr\u003eNo. The AT130EDTRFv3 requires the M92 drawtube of the AT130EDT Version II with the 3.2\" focuser, or the AT130EDX with its 3.7\" focuser. The M92 connection is not compatible with the smaller 2.5\" focuser on Version I units. If you're not sure which version you have, check the focuser barrel diameter — V2 units have the wider 3.2\" aperture.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDo I need a T-ring to connect my camera?\u003c\/strong\u003e\u003cbr\u003eIt depends on your camera. Dedicated CMOS and CCD astronomy cameras (ZWO, QHY, Player One, and similar) typically have M54 or M48 back plates built in and connect directly to the AT130EDTRFv3 — no T-ring needed. DSLR and mirrorless cameras (Canon, Nikon, Sony, Fuji, and others) connect via a T-ring for your specific lens mount, plus a step adapter to M48. The T-ring is sold separately.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat filters fit in the internal filter threads?\u003c\/strong\u003e\u003cbr\u003eStandard 2\" astronomy filters — which use a 48mm filter thread — fit directly into the upper element of the AT130EDTRFv3. This includes narrowband filters (Hα, OIII, SII), broadband LRGB sets, and light pollution rejection filters. If your filter wheel holds 2\" filters, those same filters will work here.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the correct back focus distance?\u003c\/strong\u003e\u003cbr\u003e55mm from the shoulder of the reducer to your camera's sensor. Most DSLR T-ring combinations and dedicated camera back plates land close to this naturally, but confirm with your specific camera's flange-to-sensor distance before ordering spacers. Getting this right matters for corner correction on full-frame sensors.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use this reducer with other AT refractors?\u003c\/strong\u003e\u003cbr\u003eNo. The AT130EDTRFv3 is matched to the focal length, field curvature, and M92 drawtube of the AT130EDT and AT130EDX specifically. Using it with other scopes will produce incorrect field correction and unpredictable results.\u003c\/p\u003e\n\u003ch3\u003eObserving Tip\u003c\/h3\u003e\n\u003cp\u003eAt 728mm and f\/5.6, the AT130EDT frames the large emission nebulae that would otherwise require a mosaic at native focal length. The California Nebula (NGC 1499) — over 2.5° long — fits comfortably on a full-frame sensor. The Rosette Nebula (NGC 2237) fills the frame cleanly. The North America Nebula complex has room to breathe. With a narrowband Hα filter threaded directly into the AT130EDTRFv3 and 5-minute subs, you're collecting serious data per night. The scope that was already good for color correction becomes, with this reducer in place, one of the more capable wide-field imaging instruments in its class.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse;\"\u003e\n\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAT130EDTRFv3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCompatible Telescopes\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eAT130EDT (3.2\" focuser), AT130EDX (3.7\" focuser)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFocal Reduction\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e0.8×\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e728mm (from 910mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Ratio\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003ef\/5.6 (from f\/7)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eImage Circle\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e43.8mm (full-frame)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eScope Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM92 male\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera Connections\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM78×1 female, M54×0.75 male, M48×0.75 male\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBack Focus\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e55mm (reducer shoulder to sensor)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFilter Threads\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eInternal 2\" (48mm) in upper optical element\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCoatings\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eFully multi-coated, broadband AR\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Astro-Tech","offers":[{"title":"Default Title","offer_id":41967962521673,"sku":"AT130EDTRFV3","price":299.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/0.8xReducerFlattenerAT130EDT_1-10784.jpg?v=1738261241"},{"product_id":"sky-rover-1-field-flattener-for-70-gps-refractor","title":"Sky Rover 1× Field Flattener for 70 GPS Refractor","description":"\u003cp\u003eThe Sky Rover 70 GPS is a serious little imaging system. Seventy millimeters of Super ED triplet optics delivering 420mm at f\/6 and enough speed to grab deep-sky detail in reasonable exposure times. On-axis, the imaging performance is excellent. But like any fast refractor, the triplet's inherent field curvature means that stellar images tighten toward the center while softening toward the edges — a physics limitation that becomes obvious when you examine stars across an APS-C sensor. The SR70GPSFF 1× field flattener is designed to solve exactly that problem.\u003c\/p\u003e\n\u003cp\u003eThe flattener threads directly onto the 70 GPS's integrated CAA using the standard M54×0.75 connection. It maintains the native 420mm focal length and f\/6 ratio — nothing about the scope's speed or working distance changes. What does change is that the curved focal plane becomes flat, matching the flat surface of your camera sensor. The result: sharp, round stars from the center of the frame to the corners. For a triplet this compact, adding the matched flattener transforms it from a capable grab-and-go refractor into a complete flat-field imaging platform.\u003c\/p\u003e\n\u003ch3\u003eFlattener, Not Reducer\u003c\/h3\u003e\n\u003cp\u003eThis is a 1× flattener — it preserves the native focal length and focal ratio of the 70 GPS. You maintain the full 420mm f\/6, unchanged. The field of view, exposure times, and star scale all stay the same as the uncorrected scope — you gain only what matters for imaging: perfectly flat, corrected stars across the entire sensor instead of ones that degrade toward the edges.\u003c\/p\u003e\n\u003ch3\u003eDirect CAA Threading\u003c\/h3\u003e\n\u003cp\u003eThe 70 GPS's integrated CAA features M54×0.75 female threads. The SR70GPSFF threads directly onto those threads — no adapters, no spacers, just a clean one-piece connection between scope and flattener. This integrated design gives you the mechanical simplicity and optical alignment you need for reliable imaging performance.\u003c\/p\u003e\n\u003ch3\u003eCamera Connection\u003c\/h3\u003e\n\u003cp\u003eThe camera side of the flattener connects to your imaging equipment via standard 48mm T-threads. DSLR and mirrorless cameras connect via a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring.\u003c\/p\u003e\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eSky Rover SR70GPSFF 1× field flattener for 70 GPS\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e1× field flattener — no focal reduction.\u003c\/strong\u003e Maintains the 70 GPS's native 420mm f\/6. Corrects field curvature for flat, sharp stars across the sensor without changing the imaging characteristics or working distance.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDedicated design for the Sky Rover 70 GPS triplet.\u003c\/strong\u003e Matched to the 70 GPS's optical prescription. Purpose-designed for this scope's specific field curvature profile — not a universal accessory.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDirect M54×0.75 threading onto CAA.\u003c\/strong\u003e The flattener threads directly onto the 70 GPS's camera angle adjuster. No intermediate adapters — just a solid mechanical connection that maintains optical alignment.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExcellent APS-C format imaging performance.\u003c\/strong\u003e Delivers flat, well-corrected stars across APS-C sensors at the native 420mm f\/6. Transforms a fast, portable triplet into a complete imaging system.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandard camera-side threading.\u003c\/strong\u003e DSLR and mirrorless bodies connect via a T-ring (sold separately); dedicated CMOS\/CCD astronomy cameras attach directly — 48mm T-threads are standard on most.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eDo I need this flattener for visual observing?\u003c\/strong\u003e\u003cbr\u003eNo. Field curvature only affects imaging — your eye naturally accommodates the curved focal plane during visual observation. The flattener is specifically for camera work.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow does this flattener differ from Sky Rover's GPA flatteners?\u003c\/strong\u003e\u003cbr\u003eThe GPS flatteners thread directly onto the integrated CAA's M54 output, giving you a dedicated, mechanically optimized system. GPA flatteners use different connection threads. Each Sky Rover model has a matched flattener designed for its specific optical and mechanical design.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill this fit the 60 GPS or 80 GPS?\u003c\/strong\u003e\u003cbr\u003eNo. The SR70GPSFF is designed specifically for the 70 GPS's 420mm focal length, M54×0.75 CAA threading, and optical prescription. The 60 GPS and 80 GPS each have their own matched flatteners.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat cameras does this work with?\u003c\/strong\u003e\u003cbr\u003eDSLR and mirrorless cameras connect via a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat's the back focus distance?\u003c\/strong\u003e\u003cbr\u003eIt is the industry standard 55mm. The critical measurement is the distance from the flattener's rear threads to the focal plane — ensure adequate spacing for your camera's back-focus design.\u003c\/p\u003e\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\u003cp\u003eThe 70 GPS is already an excellent compact imaging refractor. Adding the SR70GPSFF flattener completes the system. You get the triplet's speed and light-gathering, the integrated CAA's precision, and now a flat focal plane matched to your sensor. That's a professional-quality imaging platform in a scope light and portable enough to grab for an evening's work or a weekend at a dark site. It's what the system was designed to do.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse;\"\u003e\n\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBrand\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSky Rover\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSR70GPSFF\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eType\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e1× Field Flattener (no focal reduction)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eDesigned For\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSky Rover 70 GPS (70mm f\/6 Super ED Triplet)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e420mm (native — no change)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Ratio\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003ef\/6 (native — no change)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eScope Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM54×0.75 threads onto 70 GPS integrated CAA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e48mm T-threads — T-ring for DSLR\/mirrorless; direct for astronomy cameras\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Sky Rover","offers":[{"title":"Default Title","offer_id":55588537532489,"sku":"SR70GPSFF","price":159.0,"currency_code":"USD","in_stock":true}]},{"product_id":"sky-rover-1-field-flattener-for-130-gps-refractor","title":"Sky Rover 1× Field Flattener for 130 GPS Refractor","description":"\u003cp\u003eThe Sky Rover 130 GPS is a serious deep-sky imaging platform: 130mm aperture, 910mm focal length, a Super ED triplet, and a 3.7-inch focuser that gives you the precision and stability that long focal lengths demand. At 910mm f\/7, the scope is built for planetary nebulae, galaxies, and tight star clusters — the kind of targets that reward native focal length and careful focus. But like all refractors, the 130 GPS has inherent field curvature. At the eyepiece, your eye adapts to it instantly. Behind a camera sensor, it becomes visible: stars in the center are tight and round, while stars at the edges of an APS-C frame or larger sensor start to elongate. That's not a flaw — it's the optical reality of refractor design — and it's exactly what the SR130GPSFF 1× field flattener is designed to correct.\u003c\/p\u003e\n\n\u003cp\u003eThe flattener maintains the 130 GPS's native 910mm focal length and f\/7 ratio. It changes nothing about the focal length or speed — it simply flattens the curved focal plane into a flat one that matches your camera sensor. The result is sharp, round stars from center to corners at the full 910mm focal length. For a scope this capable, adding a matched flattener completes the system: you get the full resolving power of 130mm aperture at the native focal length, with corrected stars across the entire sensor.\u003c\/p\u003e\n\n\u003ch3\u003eFlattener, Not Reducer\u003c\/h3\u003e\n\n\u003cp\u003eThis is a 1× flattener — it preserves the native 910mm focal length and f\/7 ratio of the 130 GPS. If you want the full imaging power of this scope at its native focal length with a corrected field, this is the accessory. The field of view, star size, and exposure times all remain the same — you just get flat, well-corrected stars across the sensor instead of curved, elongated ones at the edges.\u003c\/p\u003e\n\n\u003cp\u003eIf you prefer a shorter focal length and faster system instead, Sky Rover offers the SR130GPSRFF 0.8× reducer, which yields 728mm f\/5.6. The choice is yours: native focal length with the flattener, or shorter focal length and faster speed with the reducer.\u003c\/p\u003e\n\n\u003ch3\u003eCamera Connection\u003c\/h3\u003e\n\n\u003cp\u003eThe camera side of the flattener connects to your imaging equipment via standard threads. DSLR and mirrorless cameras connect via a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring.\u003c\/p\u003e\n\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eSky Rover SR130GPSFF 1× field flattener for 130 GPS\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e1× field flattener — no focal reduction.\u003c\/strong\u003e Maintains the 130 GPS's native 910mm f\/7. Corrects field curvature for flat, sharp stars across the sensor without changing the imaging characteristics.\u003c\/li\u003e\n\n  \u003cli\u003e\n\u003cstrong\u003eDesigned for 910mm deep-sky imaging.\u003c\/strong\u003e At this focal length, field flatness is critical for planetary nebulae, galaxies, and other compact objects. The flattener is optimized for the 130 GPS's optical prescription.\u003c\/li\u003e\n\n  \u003cli\u003e\n\u003cstrong\u003eTransforms the 130 GPS into a complete imaging system.\u003c\/strong\u003e The 130 GPS's 130mm aperture, 910mm focal length, and 3.7-inch focuser are built for precision imaging. The matched flattener gives you flat-field performance at the native focal length — exactly what deep-sky imaging at this scale demands.\u003c\/li\u003e\n\n  \u003cli\u003e\n\u003cstrong\u003eAPS-C and larger sensor coverage.\u003c\/strong\u003e Field flatness extends across the entire width of full-frame sensors and larger formats, not just APS-C.\u003c\/li\u003e\n\n  \u003cli\u003e\n\u003cstrong\u003eStandard camera-side threading.\u003c\/strong\u003e DSLR and mirrorless bodies connect via a T-ring (sold separately); dedicated CMOS\/CCD astronomy cameras attach directly — 48mm T-threads are standard on most.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\n\u003cp\u003e\u003cstrong\u003eDo I need this flattener for visual observing?\u003c\/strong\u003e\u003cbr\u003e\nNo. Field curvature only affects imaging — your eye naturally accommodates the curved focal plane during visual observation. The flattener is specifically for camera work.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat's the difference between this flattener and the SR130GPSRFF reducer?\u003c\/strong\u003e\u003cbr\u003e\nThe flattener (this product) preserves the native 910mm focal length and f\/7 ratio while correcting field curvature. Use it if you want the full 910mm focal length and 130mm resolving power at native speed. The SR130GPSRFF 0.8× reducer shortens the focal length to 728mm and speeds up the system to f\/5.6, making exposures faster but reducing magnification. Choose based on your target scale and exposure time preferences.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWill this fit any other Sky Rover scope?\u003c\/strong\u003e\u003cbr\u003e\nNo. The SR130GPSFF is designed specifically for the 130 GPS's optical prescription and mechanical connection. Using it on a different scope will not produce correct results. Each Sky Rover scope has its own matched flattener.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat cameras does this work with?\u003c\/strong\u003e\u003cbr\u003e\nDSLR and mirrorless cameras connect via a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring.\u003c\/p\u003e\n\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\n\u003cp\u003eThe 130 GPS at 910mm f\/7 is built for the kind of deep-sky work that demands precision: tight star clusters, planetary nebulae, galaxy details. The matched SR130GPSFF flattener gives you the flat-field performance that matches the scope's optical and mechanical quality. It turns a capable imaging platform into a complete one. That's the essential pairing for 130mm refractor work.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width:100%; border-collapse: collapse;\"\u003e\n  \u003ctbody\u003e\n    \u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBrand\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSky Rover\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSR130GPSFF\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eType\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e1× Field Flattener (no focal reduction)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eDesigned For\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSky Rover 130 GPS (130mm f\/7 Super ED Triplet)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e910mm (native — no change)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Ratio\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003ef\/7 (native — no change)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eScope Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eThreads onto 130 GPS integrated CAA (M82 output — confirm)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eStandard threads — T-ring for DSLR\/mirrorless; direct for 48mm astronomy cameras\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFocuser\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eWorks with 130 GPS 3.7-inch focuser\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n","brand":"Sky Rover","offers":[{"title":"Default Title","offer_id":55588539203657,"sku":"SR130GPSFF","price":209.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/130.webp?v=1774296358"},{"product_id":"sky-rover-1-field-flattener-for-80-gps-refractor","title":"Sky Rover 1× Field Flattener for 80 GPS Refractor","description":"\u003cp\u003eThe Sky Rover 80 GPS is the portable imaging refractor in the GPS lineup — the one you grab when setup time matters. Eighty millimeters of Super ED triplet glass, 480mm at f\/6, integrated Camera Angle Adjuster (CAA), and a package light enough to ride a star tracker or travel mount without complaint. It won't gather light like the 102 or 130, but it cools down in minutes, sets up fast, and starts collecting data while larger scopes are still reaching thermal equilibrium. For the imager who values time-to-first-frame and portability, that trade-off is worth making every clear night. But like all fast triplet refractors, the 80 GPS has inherent field curvature. On-axis, the performance is exceptional. At the edges of an APS-C or full-frame sensor, stellar images soften in a gentle, predictable curve — a physics limitation that becomes obvious the moment you examine a wide-field star field. The SR80GPSFF 1× field flattener is the solution.\u003c\/p\u003e\n\u003cp\u003eThe flattener threads directly onto the 80 GPS's integrated CAA using the standard M63×1 connection. It maintains the native 480mm focal length and f\/6 ratio — speed, working distance, and exposure time all stay unchanged. What transforms is the focal plane itself. The curved surface becomes flat, matching the flat silicon of your camera sensor. Stars that were tight at center now stay tight and round all the way to the corners. For an 80mm f\/6 triplet built for imaging, adding the matched flattener is the final piece — the hardware that completes a portable, ready-to-shoot imaging system.\u003c\/p\u003e\n\u003ch3\u003eFlattener, Not Reducer\u003c\/h3\u003e\n\u003cp\u003eThis is a 1× flattener — it preserves the native focal length and focal ratio of the 80 GPS. You maintain the full 480mm f\/6, unchanged. The field of view, exposure times, and image scale all remain the same as the uncorrected scope — you gain what matters: perfectly flat, corrected stars across the entire sensor from center to corners.\u003c\/p\u003e\n\u003ch3\u003eDirect CAA Threading\u003c\/h3\u003e\n\u003cp\u003eThe 80 GPS's integrated CAA features M63×1 female threads. The SR80GPSFF threads directly onto those threads — no adapters, no spacers, just a clean one-piece connection between scope and flattener. This integrated design gives you the mechanical simplicity and optical stability you need for precise imaging work.\u003c\/p\u003e\n\u003ch3\u003eCamera Connection\u003c\/h3\u003e\n\u003cp\u003eThe camera side of the flattener connects to your imaging equipment via standard 48mm T-threads. DSLR and mirrorless cameras connect via a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring.\u003c\/p\u003e\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eSky Rover SR80GPSFF 1× field flattener for 80 GPS\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e1× field flattener — no focal reduction.\u003c\/strong\u003e Maintains the 80 GPS's native 480mm f\/6. Corrects field curvature for flat, sharp stars across the sensor without changing focal length, speed, or working distance.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDedicated design for the Sky Rover 80 GPS triplet.\u003c\/strong\u003e Matched to the 80 GPS's optical prescription and integrated CAA geometry. Purpose-designed for this scope's specific field curvature profile — not a one-size-fits-all accessory.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDirect M63×1 threading onto CAA.\u003c\/strong\u003e The flattener threads directly onto the 80 GPS's integrated Camera Angle Adjuster. No intermediate adapters — just a solid mechanical connection that maintains optical alignment and stability.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePortable imaging, corrected.\u003c\/strong\u003e The 80 GPS's advantage is speed — setup speed, cool-down speed, and f\/6 photographic speed. The flattener preserves all of that while adding flat-field performance across APS-C and full-frame sensors. You don't give up what makes the 80 GPS convenient.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandard camera-side threading.\u003c\/strong\u003e DSLR and mirrorless bodies connect via a T-ring (sold separately); dedicated CMOS\/CCD astronomy cameras attach directly — 48mm T-threads are standard on most.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eDo I need this flattener for visual observing?\u003c\/strong\u003e\u003cbr\u003eNo. Field curvature only affects imaging — your eye naturally accommodates the curved focal plane during visual observation. The flattener is specifically for camera work.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow does this flattener differ from Sky Rover's GPA flatteners?\u003c\/strong\u003e\u003cbr\u003eThe GPS flatteners thread directly onto the integrated CAA's M63 output, giving you a dedicated, mechanically optimized system. GPA flatteners use different connection threads. Each Sky Rover model has a matched flattener designed for its specific optical and mechanical design.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill this fit the 70 GPS or other Sky Rover models?\u003c\/strong\u003e\u003cbr\u003eNo. The SR80GPSFF is designed specifically for the 80 GPS's 480mm focal length, M63×1 CAA threading, and optical prescription. The 70 GPS uses M54×0.75 threads and has its own flattener. Each model has its own matched accessory.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat cameras does this work with?\u003c\/strong\u003e\u003cbr\u003eDSLR and mirrorless cameras connect via a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring. The flattener works equally well with APS-C and full-frame sensors.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat's the back focus distance?\u003c\/strong\u003e\u003cbr\u003eIt has the industry standard 55mm of back focus. The critical measurement is the distance from the flattener's rear threads to the focal plane — ensure adequate spacing for your camera's back-focus design.\u003c\/p\u003e\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\u003cp\u003eThe 80 GPS is the scope you take when you want to image tonight, not next weekend. It sets up fast, cools down fast, rides a lighter mount, and at f\/6 it collects data efficiently. Adding the SR80GPSFF flattener completes the imaging chain — you get the triplet's sharpness, the integrated CAA's precision, and now a flat focal plane matched to your sensor. That's a corrected, portable imaging system you can have shooting in minutes. For the imager who makes the most of every clear night, that's what the 80 GPS was designed to be.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse;\"\u003e\n\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBrand\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSky Rover\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSR80GPSFF\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eType\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e1× Field Flattener (no focal reduction)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eDesigned For\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSky Rover 80 GPS (80mm f\/6 Super ED Triplet)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e480mm (native — no change)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Ratio\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003ef\/6 (native — no change)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eScope Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eM63×1 threads onto 80 GPS integrated CAA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e48mm T-threads — T-ring for DSLR\/mirrorless; direct for astronomy cameras\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eImage Circle\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Sky Rover","offers":[{"title":"Default Title","offer_id":55588622303305,"sku":"SR80GPSFF","price":209.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/80apo.webp?v=1774298040"},{"product_id":"sky-rover-1-field-flattener-for-155-gps-refractor","title":"Sky Rover 1× Field Flattener for 155 GPS Refractor","description":"\u003cp\u003e\u003cmeta charset=\"utf-8\"\u003eThe Sky Rover 155 GPS is the flagship of the Sky Rover lineup — a 155mm Super ED triplet with a 1240mm focal length at f\/8. It features a redesigned CAA with a 3.7-inch clear aperture, built to match the optical precision of the scope itself. At 1240mm f\/8, this is the serious deep-sky imaging scope — the one you reach for when imaging planetary nebulae, tight star clusters, distant galaxies, and the kind of high-magnification work that separates genuine imaging systems from grab-and-go equipment. But like all refractors, the 155 GPS has inherent field curvature. At the eyepiece, your eye adapts instantly. Behind a camera sensor — especially a full-frame one — it becomes visible: stars in the center are tight and round, while stars at the edges of the frame start to elongate. \u003cmeta charset=\"utf-8\"\u003eThat’s the optical reality of refractor design — and it’s exactly what the SR155GPSFF 1× field flattener is designed to correct.\u003c\/p\u003e\n\u003cp\u003eThe flattener maintains the 155 GPS's native 1240mm focal length and f\/8 ratio. It changes nothing about the focal length or speed — it simply flattens the curved focal plane into a flat one that matches your camera sensor. The result is sharp, round stars from center to corners at the full 1240mm focal length. For a scope this capable, the matched flattener is the natural companion: you get the full resolving power of 155mm aperture at native focal length, with corrected stars across the entire sensor — even the widest full-frame frames.\u003c\/p\u003e\n\u003ch3\u003eFlattener, Not Reducer\u003c\/h3\u003e\n\u003cp\u003eThis is a 1× flattener — it preserves the native 1240mm focal length and f\/8 ratio of the 155 GPS. If you want the full imaging power of this flagship scope at its native focal length with a corrected field, this is the accessory \u003cmeta charset=\"utf-8\"\u003ethat makes it possible. The field of view, star size, and exposure times all remain the same — you just get flat, well-corrected stars across the sensor instead of curved, elongated ones at the edges.\u003c\/p\u003e\n\u003cp\u003eIf you prefer a shorter focal length and faster system instead, Sky Rover offers the SR155GPSRFF 0.8× reducer, which yields 992mm f\/6.4. The choice is yours: native focal length with the flattener for maximum resolving power, or shorter focal length and faster speed with the reducer.\u003c\/p\u003e\n\u003ch3\u003eCamera Connection\u003c\/h3\u003e\n\u003cp\u003eThe camera side of the flattener connects to your imaging equipment via standard threads. DSLR and mirrorless cameras connect via a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring.\u003c\/p\u003e\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eSky Rover SR155GPSFF 1× field flattener for 155 GPS\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e1× field flattener — no focal reduction.\u003c\/strong\u003e Maintains the 155 GPS's native 1240mm f\/8. Corrects field curvature for flat, sharp stars across the sensor without changing the imaging characteristics.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDesigned for 1240mm flagship imaging.\u003c\/strong\u003e At this focal length, field flatness is critical for the kind of high-precision, high-magnification work that defines flagship refractor performance. The flattener is optimized for the 155 GPS's optical prescription.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFull-frame sensor coverage.\u003c\/strong\u003e Designed to support full-frame sensors with strong edge performance when properly spaced. The 3.7-inch clear aperture of the 155 GPS's redesigned CAA supports the matched flattener across all formats.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe flagship deserves a flagship corrector.\u003c\/strong\u003e The 155 GPS's 155mm aperture, 1240mm focal length, and precision engineering are built for serious imaging. The matched flattener gives you flat-field performance at native focal length — exactly what flagship deep-sky imaging demands.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandard camera-side threading.\u003c\/strong\u003e DSLR and mirrorless bodies connect via a T-ring (sold separately); dedicated CMOS\/CCD astronomy cameras attach directly — 48mm T-threads are standard on most.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eDo I need this flattener for visual observing?\u003c\/strong\u003e\u003cbr\u003eNo. Field curvature only affects imaging — your eye naturally accommodates the curved focal plane during visual observation. The flattener is specifically for camera work.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat's the difference between this flattener and the SR155GPSRFF reducer?\u003c\/strong\u003e\u003cbr\u003eThe flattener (this product) preserves the native 1240mm focal length and f\/8 ratio while correcting field curvature. Use it if you want the full 1240mm focal length and 155mm resolving power at native speed. The SR155GPSRFF 0.8× reducer shortens the focal length to 992mm and speeds up the system to f\/6.4, making exposures faster but reducing magnification. Choose based on your target scale and exposure time preferences.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill this fit any other Sky Rover scope?\u003c\/strong\u003e\u003cbr\u003eNo. The SR155GPSFF is designed specifically for the 155 GPS's optical prescription and mechanical connection. Using it on a different scope will not produce correct results. Each Sky Rover scope has its own matched flattener.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat cameras does this work with?\u003c\/strong\u003e\u003cbr\u003eDSLR and mirrorless cameras connect via a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring.\u003c\/p\u003e\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\u003cp\u003eThe 155 GPS at 1240mm f\/8 is built for the kind of deep-sky work that demands excellence: tight star clusters, planetary nebulae, galaxy details, the kind of targets that reward aperture and focal length in equal measure. The matched SR155GPSFF flattener gives you the flat-field performance that matches the scope's optical and mechanical quality. It's the essential accessory for the flagship Sky Rover. That's the pairing that defines 155mm refractor imaging at its best. \u003cmeta charset=\"utf-8\"\u003eIf you’re imaging at native focal length, this isn’t an upgrade — it’s part of the system.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse;\"\u003e\n\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBrand\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSky Rover\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14py; border: 1px solid #cccccc;\"\u003eSR155GPSFF\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eType\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e1× Field Flattener (no focal reduction)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eDesigned For\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSky Rover 155 GPS (155mm f\/8 Super ED Triplet)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e1240mm (native — no change)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Ratio\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003ef\/8 (native — no change)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eScope Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eThreads onto 155 GPS redesigned CAA (3.7\" clear aperture — confirm threading)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eCamera Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eStandard threads — T-ring for DSLR\/mirrorless; direct for 48mm astronomy cameras\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eFocuser\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eWorks with 155 GPS 3.7-inch focuser\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Sky Rover","offers":[{"title":"Default Title","offer_id":55606618980425,"sku":"SR155GPSFF","price":209.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/155.webp?v=1774969087"},{"product_id":"sky-rover-1-field-flattener-for-90-gps-refractor","title":"Sky Rover 1× Field Flattener for 90 GPS Refractor","description":"\u003cp\u003eThe Sky Rover 90 GPS continues the premium legacy of the GPS lineup. Ninety millimeters of Super ED triplet glass at f\/6, delivering 540mm of focal length with the aperture to capture serious deep-sky detail.  The SR90GPSFF 1× field flattener is the final piece of your system — the accessory that completes the 90 GPS's optical and mechanical design.\u003c\/p\u003e\n\u003cp\u003eFor owners of the 90 GPS, the flattener is the natural complement. It threads directly onto the scope's integrated CAA, maintaining the native 540mm focal length and f\/6 ratio. Nothing about the scope's speed or working distance changes. What does change is that the curved focal plane becomes flat, matching the flat silicon of your full-frame sensor. The result: sharp, round, precisely rendered stars from the center of the frame to the corners. For a 90mm f\/6 triplet optimized for large-scale deep-sky imaging, the matched flattener transforms a capable scope into a complete, flat-field professional system.\u003c\/p\u003e\n\u003cp\u003e\u003cmeta charset=\"utf-8\"\u003eIf you’re imaging with the 90 GPS and want clean, usable stars across your frame without cropping the edges, this is the correct flattener for the system.\u003c\/p\u003e\n\u003ch3\u003eFlattener, Not Reducer\u003c\/h3\u003e\n\u003cp\u003eThis is a 1× flattener — it preserves the native focal length and focal ratio of the 90 GPS. You maintain the full 540mm f\/6, unchanged. The field of view, exposure times, and image scale all remain the same as the uncorrected scope — you gain what matters: flat, well-corrected stars across the entire sensor from center to corners.\u003c\/p\u003e\n\u003ch3\u003eDirect CAA Threading\u003c\/h3\u003e\n\u003cp\u003eThe 90 GPS's integrated CAA threads the flattener directly to the scope — no adapters, no intermediate accessories, just a clean mechanical connection optimized for optical alignment and stability. This integrated design is part of what makes the 90 GPS a complete system.\u003c\/p\u003e\n\u003ch3\u003eCamera Connection\u003c\/h3\u003e\n\u003cp\u003eThe camera side of the flattener connects to your imaging equipment via standard 48mm T-threads. DSLR and mirrorless cameras connect via a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring.\u003c\/p\u003e\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eSky Rover SR90GPSFF 1× field flattener for 90 GPS\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e1× field flattener — no focal reduction.\u003c\/strong\u003e Maintains the 90 GPS's native 540mm f\/6. Corrects field curvature for flat, sharp stars across the sensor without changing focal length, speed, or working distance.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDedicated design for the Sky Rover 90 GPS triplet.\u003c\/strong\u003e Matched to the 90 GPS's optical prescription.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDirect CAA threading.\u003c\/strong\u003e The flattener threads directly onto the 90 GPS's integrated correcting atmospheric adaptation. No intermediate adapters — just a solid mechanical connection that maintains optical alignment and stability.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDesigned to support full-frame imaging with strong edge performance.\u003c\/strong\u003e The 90mm f\/6 triplet is designed for serious deep-sky astrophotography. Adding the matched flattener gives you flat-field performance across full-frame sensors and the image scale needed to capture structure in extended objects.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandard camera-side threading.\u003c\/strong\u003e DSLR and mirrorless bodies connect via a T-ring (sold separately); dedicated CMOS\/CCD astronomy cameras attach directly — 48mm T-threads are standard on most.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eDo I need this flattener for visual observing?\u003c\/strong\u003e\u003cbr\u003eNo. Field curvature only affects imaging — your eye naturally accommodates the curved focal plane during visual observation. The flattener is specifically for camera work.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow does this flattener differ from Sky Rover's GPA flatteners?\u003c\/strong\u003e\u003cbr\u003eThe GPS flatteners thread directly onto the integrated CAA, giving you a dedicated, mechanically optimized system. GPA flatteners use different connection threads. Each Sky Rover model has a matched flattener designed for its specific optical and mechanical design.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eI own a 90 GPS. Is this the right flattener for my scope?\u003c\/strong\u003e\u003cbr\u003eYes. The SR90GPSFF is designed specifically for the 90 GPS's 540mm focal length, CAA threading, and optical prescription. It's the matched corrector for your system.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat cameras does this work with?\u003c\/strong\u003e\u003cbr\u003eDSLR and mirrorless cameras connect via a T-ring for your specific camera mount (sold separately). Dedicated CMOS and CCD astronomy cameras typically have 48mm T-threads built in and connect directly without a T-ring. The flattener is optimized for full-frame sensors but works equally well with APS-C.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat's the back focus distance?\u003c\/strong\u003e\u003cbr\u003eConfirm with Lonnie Wege. The critical measurement is the distance from the flattener's rear threads to the focal plane — ensure adequate spacing for your camera's back-focus design.\u003c\/p\u003e\n\u003ch3\u003eFinal Thoughts\u003c\/h3\u003e\n\u003cp\u003eIf you own a Sky Rover 90 GPS, the SR90GPSFF flattener completes the system. You get the triplet's sharpness and light-gathering, the integrated CAA's precision, and now a perfectly flat focal plane matched to your sensor. The 90 GPS was designed as a complete imaging platform, and the matched flattener is the final piece. It's the accessory that turns a very good scope into a professional-grade, field-proven imaging system.\u003c\/p\u003e\n\u003ch2\u003eTech Details:\u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse;\"\u003e\n\u003ctbody\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eBrand\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSky Rover\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eModel\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSR90GPSFF\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eType\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e1× Field Flattener (no focal reduction)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eDesigned For\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eSky Rover 90 GPS (90mm f\/6 Super ED Triplet)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Length\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003e540mm (native — no change)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eResulting Focal Ratio\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003ef\/6 (native — no change)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f0f4f8;\"\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc; font-weight: bold; width: 50%;\"\u003eScope Connection\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 14px; border: 1px solid #cccccc;\"\u003eThreads onto 90 GPS integrated CAA \u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Sky Rover","offers":[{"title":"Default Title","offer_id":55606754574409,"sku":"SR90GPSFF","price":209.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0573\/7974\/9961\/files\/155_039e2e90-371e-4373-8473-abf240070fb2.webp?v=1774980178"}],"url":"https:\/\/astronomics.com\/collections\/field-flatteners.oembed?page=2","provider":"Astronomics","version":"1.0","type":"link"}