Celestron 8" Advanced VX Series Go-To Equatorial Edge HD SCT

The Celestron AVX8 HD telescope puts 8" aplanatic EdgeHDhigh definition Schmidt optics on a precision Celestron AVX go-to German equatorial mount to make true astrographic-quality imaging and visual astronomy available at a reasonable price for almost everyone.

The Celestron AVX8HD telescope puts unique new 8" aplanatic (free from coma and corrected for spherical aberration) EdgeHD high definition Schmidt optics on a precision Celestron AVX 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 AVX 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 AVX mount combines portability and premium-level performance with a payload capacity of 30 pounds. This makes for rock-steady imaging and visual observing with the light weight 8" Celestron EdgeHD optical system, whole keeping the system very portable.

The sensible price of the AVX8HD 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 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.

To assure repeatability when you switch between Fastar and conventional imaging, the scope's optical tube is opto-mechanically aligned on a laser bench during manufacture so that all components are axially symmetric in any configuration.

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.

This Telescope's Mount . . .

Heavy duty Advanced VX Series computerized go-to German equatorial mount: This scope's Advanced VX mount was specifically designed to provide optimum imaging performance for telescopes 30 lbs and under. It has the imaging-friendly features of Celestron's larger telescope mounts, such as permanent periodic error correction (PPEC) and the ability to image across the meridian without doing a meridian flip, so you can seamlessly image the best part of the night sky.

Experienced imagers will love taking this portable mount to a dark sky site (the head weighs only 26 lbs, the tripod only 18 lbs, plus one 11 lb counterweight), as it provides all the performance of their larger observatory mounts in a portable package. If you're new to imaging, the Advanced VX mount will help you get started with the hobby and keep up with your needs for years to come.

The mount includes dual-axis slewing/tracking low-cog DC servo motors with positioning encoders on each axis for go-to computer control. The new motors provide improved tracking performance and more power to handle an unbalanced load than previous Advanced Series drives. Built-in adjustable backlash compensation and permanent user-programmed periodic error correction (PPEC) permits precise corrections during astrophotography and when observing visually at high powers. The maximum slewing speed is a fast 4° per second.

The scope is supplied with a car battery cord to operate from the cigarette lighter plug of your car or from a rechargeable 12V battery pack. The mount requires a 12VDC 3.5A power source, so the Celestron 17 amp hour capacity Power Tank #4517V is recommended for extended use in the field. The Power Tank can be recharged hundreds of times and will operate the scope all night long without danger of running out of power. Celestron AC adapter #2338PRO is also available to operate the scope from household AC in your back yard.

The sliding 11 pound counterweight is locked in place with a single hand-tighten thumbscrew each, making it easy to rebalance the scope if you add heavy photographic accessories. The mount is easily capable of handling the scope and any reasonable combination of photographic accessories you might want to use. Covers keep the motor drives free from dust and debris. A set of optional vibration suppression pads #4525 under the tripod feet will improve the telescope damping time for steadier high power observing.

To make a casual polar alignment for visual use quick and easy, there's a latitude scale and fine adjustment controls in both altitude and azimuth. The scope can be used over a wide 7° to 77° latitude range in both the northern and southern hemispheres. The scope includes Celestron's unique All-Star computerized polar alignment that lets you do an accurate polar alignment even when Polaris is hidden by trees or buildings.

Adjustable height tripod: The tripod has 2" diameter steel legs with a center leg brace for rigidity, with excellent damping characteristics. The center leg brace is drilled to form a convenient accessory tray that holds 1.25" and 2" eyepiece to keep them up out of the dew-soaked grass. The tripod can be adjusted to put the mount height anywhere from 44" to 64".

Dovetail slide bar: An adjustable Vixen-style dovetail slide bar 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. The Vixen-style dovetail on the mount allows you to use other optical tubes on the Advanced VX mount, adding to the scope's versatility.second lock knob prevents the tube from sliding off the mount should the hand-tighten knob loosen.

NexStar+ computer hand control: The supplied NexStar+ computerized hand control has a built-in database of more than 40,000 stars and deep space/solar system objects it can find for you. These include the complete RNGC, Messier, Caldwell, IC, and Abell catalogs; selected SAO stars, such as variables and multiple star systems; the planets, the Moon, and more. There is enhanced information on over 200 of the most note-worthy objects.

You can also store and edit the right ascension and declination of 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 at your command, and accurately track them for visual or photographic application.

All of the database and telescope operation information is displayed on a double line, 16-character, liquid crystal display on the hand control, which has user-selectable multiple language display (English, French, Italian, German, and Spanish). There are 19 fiber optic back-lit LED buttons to make it easy for you to control the computer without affecting your dark adapted vision. An RS-232 communication port on the hand control allows you to operate the telescope via a personal computer. The computer hand control software can be upgraded over the Internet from Celestron's website, assuring that you always have the most current software version at your command.

Several different alignment methods are built into the NexStar+ computer, allowing you to choose a level of computer accuracy in automatically finding objects with which you are comfortable. Both two-star and more-accurate three-star computer guided alignment methods are easily accomplished in only a few short minutes. You can be observing in less than 15 minutes after you first take your scope outdoors, including telescope assembly time.

In addition, the NexStar+ computer hand control is GPS-compatible (using an optional inexpensive SkySync GPS module) for full GPS (Global Positioning System) satellite accuracy. Adding GPS to the computer is something no competitive scope can do. With the Advanced Series go-to mount and the SkySync, orienting the scope in time and space on earth and aligning the scope on the sky becomes almost as easy as simply turning the scope on.

Two-year warranty: All Celestron go-to telescopes have a two-year warranty.