Celestron Advanced Series C8 1000 x 200mm N-GT Telescope

Celestron Advanced Series C8 1000 x 200mm N-GT Telescope Reviews

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Celestron Advanced Series C8 1000 x 200mm N-GT Telescope Feature

• Mounted on the CG-5GT computerized EQ mount
• 40,000+ object database with 400 user-definable objects and expanded information on over 200 objects
• Double line, 16-character Liquid Crystal Display Hand Control with 19 fiber optic backlit LED buttons
• DC Servo motors with encoders on both axes
• Proven NexStar computer control technology

Many people prefer Newtonian reflectors over refractors and catadioptric telescopes because they pack the most bang for the buck. But until recently, consumers had to choose between Dobsonian-mounted telescopes, which forced them to find and track objects manually, or very expensive, very sophisticated instruments on heavy mounts. That dichotomy left a large chasm right in the middle of the market. Can't someone make a moderately priced, reasonably large reflector on a clock-driven, computer-controlled mount? The answer is yes, they can. One company leading the way is Celestron, with their recently introduced line of "Advanced Series GT" telescopes.

The Celestron Advanced Series C8 N-GT pairs an 8-inch f/5 optical tube assembly with the redesigned CG-5GT German equatorial mount. The end result is a telescope that is easy to set up, pleasant to use, and a very good value.

The original CG-5 mount was adequate for relatively small instruments, but its tripod legs were too weak to hold a substantial instrument. The legs with the new CG-5GT are greatly improved, and similar in design to those used with Celestron's more expensive NexStar and NexStar GPS Schmidt-Cassegrain telescopes. The redesigned CG-5 mount's axes are also smoother and more stable than the original. Further, the GT version adds a NexStar computer control GoTo system that includes a database of more than 40,000 sky objects both near and far.

Throughout my tests, the NexStar GoTo system has performed very well night after night, provided it was initialized correctly (which means that the equatorial mount has to be approximately aligned with the celestial pole). Once all was set, each subsequent target was within the field of the C8-N's 20-mm eyepiece (50x). For the best views, however, I often substituted my own eyepieces. The 10-mm Tele Vue Radian, for instance, proved to be a favorite.

The C8-N has some of the finest optics I have ever seen in a Newtonian reflector. Star testing proved that the primary mirror was a nearly perfect paraboloid. That let me enjoy some wonderful observations of Saturn as well as great detail within Jupiter's turbulent atmosphere, both at 357x using my own 7-mm Pentax eyepiece (similar to this one) and 2.5x Tele Vue Powermate.

The telescope's 8-inch aperture is large enough to view all of the planets, as well as thousands of deep-sky objects. The Orion Nebula glimmers beautifully in the field, while its Trapezium multiple star is easily resolved. The C8 N-GT also shows hordes of stars in globular clusters M3, M5, and M13; the faint glow of planetary nebulae M57 and M27; and the sparkling beauty of open clusters M35, M11, and many others.

I have very few complaints about the C8 N-GT. If anything, the focuser is a little quirky. Most 2-inch focusers only require a 1.25-inch adapter, but the C8 N-GT also needs a 2-inch adapter. Both adapters look like top hats, with broad, tapered bases serving as the hat's brim. The bases are tapered to prevent the adapter from falling out of the focuser should either of the two locking thumbscrews accidentally loosen. In both cases, the eyepiece itself slips into the adapter's long tube, which protrudes about 1.5 inches above the "brim." Although it works, this dual-adapter design means having to remember yet another piece of equipment when heading out.

I also found it necessary to degrease the focuser's rack and pinion gearing. Many imported focusers come with thick, almost glue-like grease that impairs function, rather than improve it. After getting as much of the grease off as possible and spraying the gears with dry silicone lubricant, the focuser worked smoothly.

Overall, the Celestron C8 N-GT is one of the best moderately priced telescopes on the market today. Its combination of excellent optics and functional mount will combine to give users years of enjoyment. --Phil Harrington, author of Star Ware and Star Watch

Pros:

• Excellent optics
• Accurate GoTo control
• Sturdy tripod

Cons:

• Quirky focuser
• Sticky grease used as a lubricant

For a completely automated GoTo system, the C8-NGT (#31062) comes mounted on the CG-5GT computerized EQ mount and allows access to features like automatic star alignment capability and GoTo slewing to over 40,000 objects. Equipped with high speed motors and hand control, the C-8NGT allows you to remotely slew your telescope to desired objects quickly and accurately. No matter at what level you are starting out, the Advanced GT series is designed to provide you with years of observing pleasure.CG-5 Mount, Precision engineered for stability.The German Equatorial mount has precision worm gears on both axes for extremely smooth stability. The key element that makes this system the most stable in its class is the 2" Stainless Steel heavy-duty tripod legs with larger and more substantial legs that offer excellent damping characteristics for more stable views. The CG-5 also has a convenient latitude scale for easier alignment and an optional polar finder scope for the ultimate in precision alignments.

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Aug 11, 2011 06:32:04