The Celestron CGX Equatorial 800 HD 8" telescope puts unique new 8" aplanatic (free from coma and corrected for spherical aberration) EdgeHD high definition Schmidt optics on a precision Celestron CGX go-to German equatorial mount.
The Celestron CGX Equatorial 800 HD telescope puts unique new 8" aplanatic (free from coma and corrected for spherical aberration) EdgeHD high definition Schmidt optics on a precision Celestron CGX go-to German equatorial mount. The advanced EdgeHD optical design has a dual-element field flattener lens made from premium Schott optical glass in its central baffle tube that reduces off-axis coma and produces aberration-free images across a wide 42mm image circle (as large as the diagonal of a 35mm negative or large format CCD chip and ideal for astrophotography).
As Sky & Telescope said in their Hot Product for 2010 citation for the EdgeHD optics, "the EdgeHD series represents the first major redesign of the Schmidt-Cassegrain optical system that Celestron introduced in the 1960s. The addition of a two-element field flattener and coma corrector in the scope's main baffle tube produces pinpoint star images across the whole field of today's large-format CCD cameras. And the new mirror-support system reduces the image shift that was often the bane of the earlier Schmidt-Cassegrain telescopes."
In addition to reduced off-axis coma, the EdgeHD optical system delivers an astrograph-quality focal plane that is more than three times flatter than a standard Schmidt-Cassegrain telescope and dramatically flatter than other competing coma-free designs. Stars are smaller and more concentrated, creating brighter images and allowing you to see down to a fainter magnitude than other equally-sized telescopes. This guarantees you visibly sharp stars to the very edges of some of the largest CCD and DSLR chips available today.
Add Celestron's renowned Starbright XLT multicoatings on every optical surface, and the EdgeHD optic design gives you maximum light throughput across the widest possible visual and photographic spectrum. The CGEM 800HD's light grasp of almost 850 times that of even the sharpest dark-adapted eye can reveal to you star clusters, nebulas, planets, and galaxies in amazing visual and photographic detail. The Fastar-compatible optical tube allows imaging down to an incredibly-fast f/2 focal ratio using optional accessories.
The smooth and precise Celestron CGX go-to mount makes finding over 40,000 of those stars and objects easy and automatic. You spend more time looking at celestial objects, rather than looking for them. The CGEM mount combines portability and premium-level performance with a payload capacity of 40 pounds. This makes for rock-steady imaging and visual observing with the light weight 8" Celestron EdgeHD optical system.
The sensible price of the CGX8HD with Starbright XLT coatings makes true astrographic-quality imaging and visual astronomy available at a reasonable price for almost everyone. Its light weight optical tube and easily assembled mount make it easy to set up and enjoy - either in your back yard or at a distant dark sky site. Its superb flat-field reduced-coma optics and very reasonable price for afull-featured computerized go-to mount make it a telescope that willmake advanced backyard astronomer very happy for years to come.
This Telescope's Optical System . . .
EdgeHD Schmidt-Cassegrain optical tube: 8" aperture (2032mm focal length f/10). Built-in dual-element field flattener lens in the central baffle tube. Guaranteed diffraction-limited optical performance, free from coma and corrected for spherical aberrations (aplanatic design). The optical design is a Sky & Telescope Hot Product for 2010. The 17" long aluminum optical tube weighs only 14 pounds and has a large handle on the rear cell, making it easy to transport and assemble the scope in the field. For more details, click on the "EdgeHD optics" link in the support tab above.
Starbright XLT fully-multicoated optics: This high transmission/high reflectivity optical multicoatings package is applied to all optical surfaces. Starbright XLT coatings give you visibly higher light transmission for visually brighter deep space images and shorter exposure times during imaging. They also increase the contrast on subtle lunar, planetary, and nebula details when compared with a scope with ordinary coatings or multicoatings. For more details, click on the "Starbright XLT" icon above.
Tube vents: Two cooling vents located on the rear cell allow warm air to be released from behind the primary mirror when the scope is taken out for a night's observing or imaging. This shortens the amount of time needed for the optics to cool down to ambient air temperature for peak optical performance. Each vent has an integrated 60 micron micro-mesh filter guaranteed to let warm air out without letting dust in.
Fastar compatible: For the ultimate in wide-field catadioptric imaging, the EdgeHD optical tube is Fastar compatible to allow CCD imaging at a blazingly-fast f/2 focal ratio. An optional Fastar lens assembly lens replaces the telescope's removable secondary mirror (an exchange that takes only a few minutes). Your CCD camera is attached to the Fastar lens. This puts your camera at the f/2 position in the center of the Schmidt corrector lens at the front of the scope, rather than in its normal f/10 position at the Cassegrain focus at the rear of the scope.
Focusing: Focusing is accomplished by turning a knob at the rear of the scope body that moves the primary mirror fore and aft along a central baffle tube to adjust the focus. The Celestron focusing mechanism is supported by two pre-loaded ball bearings, minimizing the "mirror flop" typical of bushing focus mechanisms that causes image shift during critical focusing.
Mirror locks: Flexible tension clutches hold the mirror in place after correct focus is achieved for imaging and reduce image shift when rotating the tube around the mount (while moving past the zenith during astrophotography, for example). Unlike other designs that have only one locking knob located off to one side of the mirror, the Celestron system uses three locks equally spaced around the mirror to distribute the mirror locking force symmetrically. The focuser itself acts as one of the locks, while two flexible rods spaced 120° away in either direction act as the second and third locks. Controlled by variable tension knobs on the rear cell, these rods act in conjunction with the focuser to hold the mirror in place without putting any asymmetrical force or pressure on the mirror. This keeps the image centered in the eyepiece (or chip) no matter what the orientation of the optical tube.
Finderscope: 9 x 50mm straight-through achromatic design, with a wide 5.8° field of view, mounted in a spring-loaded easy-adjust quick release bracket.
Visual back: Removable 1.25" visual back holds visual accessories such as star diagonal, tele-extender, etc.
Star diagonal: 1.25" prism type.
Eyepiece: 1.25" 40mm Plössl (51x). The eyepiece field of view is 0.84 degrees, almost 70% larger than the full Moon.
The Celestron CGX is culmination of years of engineering by the USA R & D division of Celestron. The CGX isn't just a pretty face, the mechanics and ergonomics are upgraded as well. Celestron has taken their equatorial mounts to a higher level than ever before.
The new CGX looks like a cross between the CGEM II and the CGE Pro mount from Celestron. The ergonomically-designed CGX has a fresh, attractive, bold appearance and easier set-up of than earlier EQ mounts. It has been uprated with mechanical and electronic changes to a 55 pound payload capacity. The new design allows for a lower profile EQ head with a better balance point. Celestron has also added a integrated handles to assist with setup and transportation.
The CGX mount head contains dual-axis slewing/tracking motors on each axis for go-to computer control. This is where the real upgrades start. The mount uses spring-loaded worm gears with belt drives. The belt drives offer smooth, quiet operation and precision slewing and tracking. The motor armatures are skewed to minimize cogging for precise jitter-free low speed tracking. The motor drives and their wiring are all internal, keeping them snag-free and free from dust and debris.
Redesigned electronics deliver constant regulated power to the motors, making them capable of driving the telescope even when the mount is not perfectly balanced. This allows the CGX to have the payload capacity of much larger mounts without sacrificing smooth tracking motion and pointing accuracy across the entire sky. The mount of course supports the SkyPortal WiFi (for your smart devices) as well as the StarSense AutoAlign putting cutting edge control and setup at your disposal.
The mount requires a minimum 3.5 amp 12 VDC power supply to operate. The maximum 3.5 amp power draw happens only briefly when accelerating to the high speed slewing mode from a standing start, or decelerating from the high speed mode when approaching a computer-chosen object. Normal power draw with a well-balanced payload is generally less than half the maximum draw.
The mount comes with a car battery cord to operate from the cigarette lighter plug of your car or from a rechargeable 12V battery pack. The 17 amp hour capacity Celestron Power Tank #4517V is recommended and will operate the mount all night long without danger of running out of power.
To make a casual polar alignment for visual use quick and easy, there's a latitude scale with large ergonomically-friendly altitude and azimuth adjustment knobs. No polar alignment finderscope is available to aid in the precise polar alignment required for long exposure astrophotography, nor is any needed. A unique Celestron All-Star Polar Alignment program built into the NexStar hand control helps you do a very precise computerized polar alignment in mere minutes, using any bright star, even when Polaris is hidden by trees or buildings. It works in both northern and southern hemispheres. This technology basically gets rid of the need for a polar alignment scope.
The two supplied 11 pound counterweights lock in place with a single hand-tighten knob, making it easy to rebalance a scope if you add heavy photographic accessories. If needed, optional counterweights are available to balance very heavy loads.
For observing or imaging objects near the meridian (the imaginary line passing directly overhead from North to South), the CGX is designed to track 20° past the meridian for uninterrupted imaging through the most ideal part of the sky.
There are nine motor drive speeds: 0.5x and 1x sidereal for guiding; 4x, 8x, 16x, and 64x for centering; and 1°, 2°, and a fast 5° per second for slewing. Preset tracking rates include sidereal, solar, and lunar. Equatorial tracking modes are available for both northern and southern hemispheres.
New for the CGX mount is a telescope control software that has been developed in conjunction with Planewave Instruments. Planewave Instruments produces some of the most sophisticated imaging systems on the planet. The features of the included software are extremely robust. They include multi-point goto modeling, focusing, and plate solving. You will no longer need a third party advanced PC control software as this has it all.
The supplied NexStar computer hand control has a built-in database of more than 40,000 stars and objects. These include the complete RNGC, Messier, Caldwell, IC, and Abell catalogs; selected SAO stars; the planets, the Moon, and others. The custom database lists of all the most famous deep-sky objects by name and catalog number; the most beautiful double, triple and quadruple stars; selected variable stars; non-planetary solar system objects; and asterisms.
You can also store and edit the right ascension and declination of 100 additional user-defined objects of your own choosing, such as the comet and asteroid coordinates published monthly in Astronomy and Sky & Telescope magazines. The computer control can find any of those objects with only a few keystrokes, and track them with high accuracy for visual or photographic applications. There is enhanced information on over 200 of the most note-worthy objects.
The NexStar computer control of the smooth and precise CGX go-to mount makes finding over 40,000 stars and objects easy and automatic, so you can spend more time looking at them, rather than looking for them.
All of the database and mount operation information is displayed on a double line, 16-character, liquid crystal display on the hand control. There are 19 fiber optic backlit LED buttons to make it easy for you to control the NexStar computer without affecting your dark-adapted vision. A USB 2.0 communication port on the hand control allows you to operate the telescope via a personal computer using a USB cable and NexRemote software CD-ROM.
The NexStar hand control provides a constant digital r. a. and dec readout of the scope's position on the sky. This provides much greater accuracy than conventional manual setting circles for star-hopping or locating objects by their celestial coordinates alone, should you want to observe the old-fashioned way without using the computer to find objects for you.
The software built into the NexStar hand control includes mount calibration, database filter limits, hibernate, five alignment procedures, user-defined slew limits, a new "All-Star" polar alignment routine that uses any bright star for a quick and accurate polar alignment, and more. Built-in adjustable backlash compensation permits precise corrections during astrophotography and when observing visually at high powers. A high precision pointing subroutine in the computer lets you point accurately at objects that you want to photograph that are too dim to be seen though the scope.
The software includes permanent programmable periodic error correction (PEC) to correct for the minor periodic tracking errors inherent to all worm drives that might otherwise mar your long exposure photographs. The CGX mount retains the PEC recordings when it is powered down. The hand control and motor control software is flash-upgradeable to allow you to download the latest product updates over the Internet to keep your CGX mount always at the cutting edge of technology.
An autoguider port is located on the electronic pier for long exposure astrophotography. The autoguider port can use a six-pin RJ-12 modular jack ST-4 compatible CCD autoguider to automatically control the drive motors during long exposure astrophotography.
Five different alignment methods are built into the Celestron mount's NexStar computer - 2-star align, quick align, 1-star align, last alignment, and solar system align. This allows you to choose a level of computer accuracy in automatically finding objects with which you are comfortable. Alignment is easily accomplished in only a few short minutes. You can be observing in less than 15 minutes after you first take your CGX-mounted scope outdoors.
In addition, the NexStar computer hand control is GPS-compatible (using an optional inexpensive SkySync GPS module) for full GPS (Global Positioning System) accuracy. Adding GPS to the computer is something no competitively-priced mount can do. Once the scope is approximately polar aligned, the 16-channel SkySync GPS system uses signals from government satellites to calculate the scope's location on earth with an accuracy measured in meters. The system also calculates the current time based on the split second accuracy of the GPS time signals.
After the SkySync quickly completes these calculations and enters the information into the computer control for you automatically, the computer then orients the scope with the sky, slews to a pair of guide stars, asks you to confirm that the stars are in the center of the field (and center them if they're not precisely aligned), and then starts finding and tracking over 40,000 objects for you at your command. With the CGX go-to mount and the SkySync, orienting your scope in time and space on earth and aligning it on the sky becomes almost as easy a task as simply turning the mount on.
The new, 2"diameter adjustable height tripod has graduated markings on the legs to help with quick leveling. The center leg brace is drilled to form a convenient accessory tray that holds 1.25" and 2" eyepieces to keep them up out of the dew-soaked grass.
Optical tubes are installed on the CGX mount using a Dual-Slot on the mount head that accepts a Celestron CGE-style or Losmandy D-plate dovetail slide bar as well as the narrower Vixen Style dovetail. This allows the optical tube to be quickly and precisely balanced fore and aft on the mount, eliminating the need for an extra counterweight to balance a camera or other accessories. Setup and takedown times are exceptionally fast, as a single large hand-tighten knob holds the optical tube in place. A second lock knob prevents the tube from sliding off the mount should the hand-tighten knob loosen.
