Home > Telescopes > Celestron > CGEM II > Celestron Telescope Astrograph S 203/400 RASA 800 CGEM II GoTo

Digital Schmidt camera for wide angle astrophotography!

This astrograph makes it very easy to create stunning photos with a modern DSLR or astronomical CCD camera. The new optical design has a four-lens corrector, incorporating rare earth glass, which suppresses chromatic aberrations and other problems such as coma and field curvature. Never before has an astrograph in this price range delivered such optical quality and spot size over the entire image field. The design also allows for a very low vignetting.

• super-fast 11" f2.2 optics - sharply images APS format and is even optimized for sensor sizes up to a 70mm field diagonal.
• extremely short exposure times - the RASA Astrograph acquires images twenty times faster than at f10! Thirty seconds at f2.2 correspond to ten minutes at f10 - tracking control is hence superfluous!
• huge field of view - with a 620mm focal length, makes wide-angle shots a piece of cake and you and always have an overview
• excellent focusing mechanism - new bronze bearings reduce image shift, the 10:1 FeatherTouch micro-focuser allows highly precise focusing!
• innovative Features - quieter 12V MagLev fan reduces the cooling phase, keeps out dust and allows optimum air circulation in the OTA. Various adapters for popular camera brands are included. Back focus for the camera supplied adapters: 55mm, back focus for the front lens group: 69.26mm

RASA stands for Rowe-Ackermann-Schmidt Astrograph - Dave Rowe and Mark Ackermann are renowned optical instrument designers. Together, they hold numerous patents on their inventions. The RASA astrograph combines their expertise and experience.

Note: The RASA 800 doesn't work with regular DSLR cameras (because of a short backfocus). It is recommended to use the RASA 800 with mirrorless cameras or small dedicated CCD or CMOS astronomical cameras.

CGEM II mount

Celestron has updated its popular CGEM mount. Version 2 features a sturdier tripod, USB port, dual dovetail clamp for Losmandy and Vixen standards, improved ergonomics and firmware!

But it has not changed the tried and tested features of the CGEM, which continues to be a highly reputable mount for astrophotography - safely carrying Celestron SC OTAs of up to 11-inch (279mm) aperture for astrophotography purposes. Of course, you can also use the CGEM with telescopes from other brands, whether refractors or medium-sized Newtonian telescopes. The dual saddle clamp is suitable for the two common prism rail formats (also known as dovetail rails). The saddle clamp has two large, handy screws that can even be easily operated when wearing gloves. Since the clamp engages over its entire width with the prism rail and not just the screws themselves, no damage to the rail can occur during setting up.

Additional advantages of the CGEM II

• the tripod legs are marked, allowing you to extend the legs to a consistent length and easily remember your preferred length.
• built-in All-Star Polar Alignment by Celestron to align the mount using any star. So you do not need a polar finder and do not have to separately north align. You do not even need a clear view of the Pole Star! The screw for adjusting the polar height is large and convenient. This is an important advantage, as the polar height adjustment must be done with the weight of the OTA present.
• large database of all popular deep sky objects, catalogued by name and catalogue number; the most famous double, triple and quadruple stars as well as variable stars and objects within the solar system.
• Permanently Programmable Periodic Error Correction (PPEC)
• double-line, 16-character LCD hand control with backlit buttons. The hand controller has a USB port for easy connection to the PC for firmware updates of the mount and hand controller.
• tracking beyond the meridian by up to 30° - so that long-term exposure astrophotography does not have to be suddenly interrupted.

The CGEM II is between the AVX and CGX mounts in Celestron's range of modern equatorial GoTo mounts. For beginners, we recommend the low-priced AVX - which has all the advantages of NexStar + electronics, but is not mechanically designed to carry large OTAs. The CGX mount meets the highest demands of astrophotographers, even when carrying heavy equipment. Finally, the CGEM II is an excellent compromise between carrying capacity, performance and price. It is the workhorse of sophisticated astrophotographers.

It is not only important which telescope you buy, but also where you buy it.

We provide extra help:

• We are a leading telescope dealer and know these instruments like the back of our hands.
• We are always very happy to offer our assistance after your purchase, should you encounter any problems with your telescope’s setup or operation.
• Our ‘Telescope Basics’ booklet - an 80-page beginner's guide for our telescopes – is provided free of charge with every telescope we sell.