Catadioptric Telescopes - Astronoscope

A catadioptric telescope combines reflector and refractor optical systems by using a mixture of lenses, mirrors and correctors to deliver an image to the observer. This type of telescope has a greater degree of error correction than other telescope types and therefore delivers a greater aberration free field of view. They are particularly well suited to Astrophotography

Their physical length is deceptive as their folded optical path offers a much greater focal length than the appearance of the tube would suggest.