The Schmidt-Cassegrain optics by Celestron:
Despite the long focal length of these telescopes, the OTA itself has a very short length, making the system a compact telescope which is extremely easy to transport. Light first hits an aspherically figured Schmidt corrector plate and is then thrown onto a spherical main mirror. This reflects the light back up, throwing it onto a secondary mirror which subsequently throws it back in the direction of main mirror. The light then passes through a central hole in the main mirror and into the focuser at the bottom of the OTA. Thus the system is closed and hence does not suffer from air turbulence which could degrade the image. Of course this also means that the system is optimally protected from dust. The Schmidt plate is multi-coated, ensuring bright images which do not suffer from stray light reflections.
This telescope provides a very good image, boasting high contrast and definition and provides a lot of pleasure when planetary observing. The Schmidt-Cassegrain design provides a good all-round system suitable for both observing and astrophotography and with an enormous range of optional accessories available. Using the bottom end of the OTA to look through means easy orientation. The system is also optimal for occasional terrestrial observing, e.g. birdwatching at close range. Celestron SC telescopes have an aperture ratio of around 1:10 which, so astrophotography is also very easily possible.
Main mirror focusing means a very large range of focus is made available, which allows virtually any common accessory to be used. Two pre-loaded ball bearings are used in the main mirror focus positioning mechanism in order to prevent 'mirror shift' - a typical problem when using simple bushings. The use of high quality materials such as CNC-milled aluminium components, cast steel and stainless steel guarantees extreme robustness with low weight. This means that a very heavy mount is unnecessary, not always the case for other telescope designs.
Features of the optics:
- long focal length with short OTA
- low weight aluminium OTA
- high quality XLT multi-coating
- closed system
- pre-loaded ball bearings for low mirror shift main mirror focusing
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 not only matters which telescope you buy but also where you buy it. Our additional services:
- We are a leading telescope dealer and know the devices we sell. Our customer service team will gladly help you after your purchase if you have problems with assembly or operation.
- We provide a copy of the 80-page Telescope ABC beginners handbook with every telescope.
