Celestron CGX 925 EdgeHD

CGX 925 EdgeHD
The CGX mount only resembles the cheaper CGEM-II at first glance, but has been developed from scratch and offers much more.

The 20 kg mount has a real, photographic payload of 25 kg. This means that you can really work with a 25 kg payload and do not have to plan generous reserves for photography, as is often the case. Thanks to the large carrying handles, it is even easier to transport than a comparable, somewhat lighter classic equatorial mount! With the dual dovetail clamp for CG-5 (Vixen, Celestron) or CGE (3-inch), you can easily switch between small solar telescopes and large Schmidt-Cassegrains, for example.

To make this fun for photography too, the mount has been given more powerful, responsive motors, which are connected to the axes via a sturdy toothed belt. This means that the mount reacts almost immediately to control commands, even from an autoguider. There is no gear backlash, and since the worm gears are also spring-loaded, the backlash is largely eliminated - you do not have to readjust even with large temperature differences, worms and gears have optimum contact.

The new, large screws are easy to grip so that you can loosen or tighten them easily even when wearing gloves - the pole height adjustment has also been revised so that you can easily adjust the mount even when fully loaded. A polar finder will be available as an option, but is generally unnecessary: with the All-Star polar alignment, you can align the mount to any brighter star through the telescope, and for perfection, the alignment is always superior to the polar finder. As a special feature, you can move the mount on the base plate of the extra-wide tripod head - so you can place the center of gravity perfectly over the tripod, for the entire usable latitude range from 3 to 65° north or south latitude. The flat base can also be easily adapted to your own columns.

As a photo mount, it is just as suitable for mobile use as it is for remote operation. Internal sensors ("switches") automatically bring the mount into the home position and prevent it from moving too far during panning and hitting anything. The internal cabling also ensures safety: all connections (power, hand controller, AUX and autoguider) are in the base of the mount and do not move with it.

The hand controller can be controlled in the classic way via ASCOM and the hand controller (new: with USB connection) vie PC, or you can use the control software included in the scope of delivery, which was developed together with Planewave Instruments. Multipoint GoTo modeling, plate solving and control of the focuser are just some of the functions that you normally have to retrofit for remote operation - with the CGX, this software is included in the scope of delivery. Here you do not need the hand controller, but can use the USB port of the mount directly.

The telescope:
The EdgeHD optics (Edge High Definition) combine the compact design of a Schmidt-Cassegrain with significantly improved imaging at the edge of the image. This optical system not only offers the properties of astrographs, but also produces completely undistorted, sharp images right up to the edge of the large visual and photographic field of view. This not only corrects the coma outside the optical axis - as with other so-called "coma-free" optical designs available on the market (see also our test image) - but also the image field curvature!

The difference
Many optical systems are propagated as "astrographs"; however, they produce the coveted "pinpoint" star image along a curved image plane. On images taken with modern CCD cameras, the result is a noticeable curvature of the image field which increases towards the edge of the image field and becomes stronger the larger the chip is; i.e. the stars remain round, but are blown up into small rings ("donuts") towards the edge.

With the CELESTRON Edge HD telescopes, in addition to the coma, this image field curvature is also corrected out to the edge, so that even images with large CCD chips are completely sharp, with uniformly large star images over the entire chip - right into the corners of the image field.

This also significantly improves resolution and limiting magnitude compared to competing optical systems of similar aperture. The Celestron XLT multi-coating also helps the Edge HD optics to achieve a significant increase in performance compared to similar systems on the market.

In addition to the new optics, the mechanics and tube have also been completely redesigned.
The innovations include:
Mirror locks
hold the primary mirror in any focus position without exerting pressure on the optical elements. The image always remains stable on the chip, even with long exposure times.

Ventilation openings
behind the primary mirror ensure rapid air exchange so that the optics cool down unrivalled quickly. Thanks to an air filter system, no dust gets into the tube.

HyperStar-compatible
With all EdgeHD tubes, you can remove the secondary mirror and replace it with the optional HyperStar optics. The result: your standard Celestron EdgeHD telescope becomes a digital Schmidt design for your CCD or DSLR camera for photography in primary focus at f/2 (C8, C11) and f/1.9 (C14).

Axiom eyepieces
The Edge HD 9.25 is supplied with an Axiom eyepiece from Celestron. With a focal length of 23 mm and 82° field of view, you get an impressive combination of magnification and field of view.