Flat-Fielded Maksutov-Cassegrain Optical Systems

The aim of this paper is to investigate the construction of an optical system of spherical or figured spherical surfaces suitable for astronomical photography, which would form optical images of high quality on a sufficiently large and practically flat field. The systems described use a pierced primary concave and a secondary convex mirror, together with the smallest number of correcting lenses to cancel out the aberrations resulting from the use of spherical or nearly spherical mirrors. It is totally enclosed, and covers a field of just under 4 deg.