Celestron Schmidt-Cassegrains

More Information  · Supplied Accessories  · Recommended Accessories  · Images of Some Features Price $3,654.00 List Price $6,717.95 Highest Useful Magnification 406x Visual Limiting Magnitude 14 Focal Length 2032mm Focal Ratio f/10 Resolution 0.57 arc seconds Aperture 8" Weight 95 lbs. Heaviest Single Component 42 lbs. Warranty 2 years

This Telescope’s Optical System . . .

• Schmidt-Cassegrain carbon fiber optical tube: 8" aperture (2032mm focal length f/10). Guaranteed diffraction-limited optical performance. The 17" long optical tube weighs only 13 lbs., making it easy to transport and assemble in the field. The optical tube is made of virtually indestructible nine-layer carbon fiber composite, rather than dentable aluminum. Carbon fiber tubes are unavailable with competitive go-to scopes. Because of the low coefficient of thermal expansion of carbon fiber composites (1/40th that of aluminum), serious astrophotographers don’t have to worry about temperature changes causing the optical tube to expand or contract in length and change the focus during a critical CCD exposure.

• Starbright XLT fully multicoated optics: This coatings package includes high reflectivity multilayer aluminum mirrors enhanced with titanium dioxide for high reflectivity, plus a unique combination of magnesium fluoride and hafnium dioxide antireflection coatings on both sides of the Schmidt corrector lens. The corrector lens itself is made of high transmission water white float glass that has 3.5% higher light transmission than the conventional soda lime glass used in other telescopes. Starbright XLT multicoatings visibly increase the contrast on subtle lunar, planetary, and nebula details when compared with a scope with standard multicoatings. They also give you higher light transmission for brighter deep space images and shorter exposure times during CCD and 35mm photography. Across the total visual/photographic spectrum from 400nm to 750nm, independent laboratory tests show the new Starbright XLT coatings are 16% brighter overall than even industry-standard Starbright multicoatings.

• Hand-figured optics: Hand figuring the optical system is a complex optical procedure done on a commercial basis only by Celestron. Four separate optical tests are made on every set of optics, using a double-pass laser autocollimator – an Airy disc inspection, a test for spherical aberration by examining the diffraction images on both sides of focus, a Ronchi grating test, and a knife edge test. A skilled optician evaluates these tests, then fabricates a precision pitch lap and delicately hand polishes the secondary mirror to compensate for any small residual zonal defects and smooth the optical figure. Done a few strokes at a time, and testing constantly to evaluate their effect, this final hand-figuring can take hours. But, when it is finished, the optical performance makes every tedious hour of hand-crafting well worth the effort.

• Fastar Compatible Optics: This special optical system allows CCD imaging at an incredibly fast f/1.9 focal ratio. With an optional Fastar lens assembly replacing the scope’s secondary mirror assembly (an exchange that takes only minutes) and a $499 SAC Imaging SAC7C CCD camera, the 8" CGE-800 will record a huge 23 x 31 arc minute field – almost large enough to encompass the entire full Moon in a single frame and eight times the image area of an $2695 camera on the same scope without Fastar optics. Only Celestron scopes have Fastar compatible optics.

• Finderscope: 6 x 30mm straight-through achromatic design, with a wide 7 degree field of view. It focuses by loosening the trim ring behind the objective lens cell, screwing the lens cell in or out to focus, and tightening the trim ring to lock in the correct focus.

• 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" 25mm Plössl (81x). The eyepiece field of view is 0.59 degrees, almost 20% larger than the full moon.

This Telescope’s Mount . . .

• Heavy duty CGE German equatorial mount: The mount is fabricated of CNC machined aluminum and stainless steel. The drive system (completely enclosed for safety) uses U.S. manufactured Pittman 12V DC slewing and tracking servo motors and U.S. manufactured Berg bronze drive gears mated with stainless steel worm shafts. The motors have integrated optical encoders to relay the scope’s position to the computer hand control. The 256 counts per revolution encoders are used in quadrature for a high resolution 0.11 arc second accuracy for precise positioning when the scope slews from object to object. There are home sensors on both RA and Dec axes, and fail safe slew limit switches in RA. Smooth ramping of the slew motors reduces wear on the drive train.
     The right ascension axis has a 1" diameter solid ground stainless steel shaft supported by two preloaded 0.9835" ID x 2.047" OD tapered roller bearings and one 4.724" OD x 3.543" ID thrust bearing. The 180-tooth 5.625" diameter bronze main drive gear is preloaded to maintain gear mesh even when the clutch tension varies. The 0.4375" diameter worm is precision-machined from 303 stainless steel. A 4-point RA clutch system provides no-slip pointing precision and positive engagement, no matter what the load.
     The declination axis uses a 1" solid ground stainless steel shaft with two preloaded 0.9835" ID x 2.047" OD tapered roller bearings and one 3.250" OD x 2.500" ID thrust bearing. The 180-tooth 5.625" diameter bronze declination drive gear is preloaded to maintain gear mesh while the clutch tension varies. The 0.4375" diameter declination worm is precision-machined from 303 stainless steel.
     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. If long exposure astrophotography is in your plans, an optional polar finder is available to increase the accuracy of your initial alignment. For ultimate accuracy, the scope’s computer hand control has polar alignment routines for a more precise polar alignment in both Northern and Southern hemispheres.
     An adjustable 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 tube 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 dovetail mounting system makes it easy to adapt the CGE mount to other optical tubes. The mount’s sliding counterweight is locked in place with a single hand-tighten thumbscrew, making it easy to rebalance the scope if you add heavy photographic accessories. With a payload capacity of 65 pounds, the mount is easily capable of handling the 13 pound optical tube and any combination of photographic accessories you might want to use.
     A car battery cord is supplied to power the scope from the cigarette lighter plug of a car or a rechargeable battery pack. The optional #4512V Celestron Power Tank 12V DC 7 amp-hour multipurpose rechargeable battery pack will power the scope for a full night’s observing and longer. An optional AC adapter is available for backyard or observatory dome operation. The CGE mount can operate over a latitude range of 10 degrees to 60 degrees.

• Adjustable height tripod: The tripod has 2.75" diameter powder-coated cold-rolled carbon steel outer legs. The extendable inner legs have a diameter of 2.375". The height is adjustable from 36" to 50". Dual leg support provides exceptional rigidity, as a center leg brace provides outward preload while a lower leg brace provides inward preload.

• Electronics: The drive base features a CCD autoguider port, an RS-232 serial port for connecting to a laptop or PC for remote operation, strain relief power cord cable protection, and a backlit power switch. The scope’s computerized hand control can show you the planets and thousands of deep space objects the very first night you use your scope – even if you've never used a telescope before! The computer’s memory contains the following objects:
  • the entire RNGC (Revised New General Catalog) of 7840 nebulas, galaxies, and star clusters

  • the IC (Index Catalog) of 5386 nebulas, galaxies, and star clusters

  • the Messier Catalog of the 110 best known deep sky objects

  • the Caldwell Catalog of 109 fascinating objects that Messier missed

  • 20 famous asterisms

  • the Abell Catalog of 2712 galaxy clusters

  • 25 selected CCD imaging objects

  • 29,500 selected SAO stars

    Also included are the eight major planets out to Pluto and the Moon, for a total database more than 45,000 stars and objects. It’s enough fascinating objects to keep you busy observing for the rest of your life.
       You can also store and edit the right ascension and declination of an additional 400 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 and center any of those objects with 1.5 arc minute accuracy at your command, and track them with high accuracy for visual or photographic application.
       There’s a real time clock that maintains the time even when the scope is powered down. The scope has a hibernate mode that maintains the telescope alignment on the sky of a permanently-mounted scope even while the scope is powered down. Built-in permanent programmable periodic error correction corrects the periodic tracking errors inherent in all worm drives to allow sharper astrophotographic images, with fewer guiding corrections needed. Built-in adjustable backlash compensation permits precise corrections during astrophotography and when observing visually at high powers. User-programmable filter limits allow you to display only objects above your local horizon.

• GPS adaptable: The addition of an inexpensive Celestron CN16 GPS module provides the CGE mount with full GPS (Global Positioning System) satellite accuracy. Once the scope is approximately polar aligned, the 16-channel CN16 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 CN16 quickly completes these calculations and enters the information into the computer control for you automatically, the computer can then orient the scope with the sky, slew to a pair of guide stars, ask you to confirm that the stars are in the center of the field (and center them if they’re not precisely aligned), and then start finding and tracking over 45,000 objects for you at your command. With the CGE mount and the CN16, orienting the scope in time and space on earth and aligning the scope on the sky becomes almost as easy a task as simply turning the scope on.

• NexRemote software features: NexRemote telescope control software allows you to control the NexStar CGE800X from your personal computer or laptop. NexRemote provides full emulation of every aspect of the Celestron computerized hand control including: alignment in any tracking mode; go to any database object; setup of user objects; hibernation; connection to popular planetarium programs; etc. In addition to emulating the NexStar hand control, NexRemote adds powerful new features that let you keep your eyes on the stars instead of the LCD by enabling talking computer speech support using your computer’s built-in speaker; control the objects you want to see and the order that you see them; create and save custom tours by launching NexTour; take wireless control of the telescope with optional gamepad support; connect your personal GPS device to NexRemote using NexGPS; download NexRemote updates online to use the latest features; and more. The NexRemote software includes an RS-232 cable to connect the NexStar CGE800X to a PC.

• Two-year warranty: All Celestron go-to telescopes have a two-year warranty, double that of competitive go-to scopes.