Abstract: A compact reflector telescope has a spherical primary reflector and a secondary reflector with a negative lens interposed there between in axial alignment therewith. Light reflected from the primary reflector is passed through the negative lens and is diverted by the secondary reflector to a positive lens at the side of the telescope tube. The positive lens focuses the light rays onto an eye piece or ocular or onto a photographic emulsion or electronic detector. The telescope reduces or substantially eliminates spherical aberration and can be configured to have a focal ratio significantly greater than the focal ratio of the primary reflector. The telescope produces a flat field of view and an image which is substantially diffraction limited.