Schmidt-Cassegrain telescope


The Schmidt-Cassegrain telescope is a variation of the Schmidt camera to enable visual observation. It uses a convex spheroidal secondary mirror to reflect the converging beam from the primary back through a central hole in the primary, allowing an eyepiece to be mounted at the back end of the tube.


While a Schmidt-Cassegrain is compact and gives excellent results when not pushed near its design limits, the relatively large secondary obstruction reduces image contrast. This, and other design compromises, mean that this telescope cannot match the optical performance of Maksutov telescopes or Newtonian reflectors of equal manufacturing quality.