Celestron - 9.25" EdgeHD (Optical Tube) mount High-precision worm gears

High-precision worm gears

Cassegrain telescopes are traditionally more advantageous than other similar designs such as SCT's which generally contain more basic spherical mirrors and a larger central obstruction

It is very versatile and allows a variety of adaptations - especially in combination with other M48 and T2 adapters

the penetration of humid room air is prevented

This gives you then 60mm backfocus

Celestron - 9.25" EdgeHD (Optical Tube) mount High-precision worm gearsThe 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. Not only is the coma outside the optical axis corrected as with other "coma free" optical designs