The Celestron EdgeHD telescope: Corrected image - sharp right up to the edges!
EdgeHD is the name for Celestron’s “aplanatic Schmidt Cassegrain telescope”. After over 50 years of success, Celestron has revolutionised the classic Schmidt Cassegrain telescope.
EdgeHD telescopes ( "Edge High Definition") are true astrographs. This optical system delivers distortion-free, sharp images right to the edge of the visual field. This means that not only the coma outwith the optical axis is corrected, as is the case in currently available “coma-free” lens designs, but also field curvature.
Lots of optical systems are advertised as “astrographs”. As desired, they display stars with pin-sharp clarity, but along a curved image plane. Photographing this using a camera results in a noticeable image field curvature which rises towards the edge of the image field, resulting in increasing star size and aberations with larger sensors. The stars at the edge expand into small rings (“doughnuts”). As well as the coma, the Celestron Edge HD telescopes correct field curvature right up to the edge of the image. This also significantly improves resolution and magnitude limits in comparison to rival optical systems.
The XLT multi-coating helps to give the EdgeHD scopes a significant performance boost compared to similar systems on the market.
The Edge HD telescopes’ mechanisms and lens tube have been fully overhauled:
- mirror clamps hold the primary mirror securely in any desired position without putting pressure on the optical elements. The image is stable, even during long exposure times.
- Air vents behind the primary mirror provide fast air exchange so that the lens cools amazingly quickly. Thanks to an air filter system, dust is prevented from entering the lens tube.
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.
