Short focus projection lens of retrofocus type - has five specified single members to avoid need for condenser change and vignetting

摘要

The short-focus projection lens has the entry and exit opening displaced towards the image. It consists of five single lens members, i.e. in direction of light passage a first biconvex lens (1,2) followed by a biconcave lens (3,4), a positive meniscus lens (5,6) convex towards the object, a biconvex lens (7,8), and a negative meniscus lens (9,10) which is arranged at the rear focus of the objective and convex towards the object. The refractive powers of the individual lenses are specified as are curvature radii, lens thicknesses and air gaps, refractive indices and Abbe-numbers for two examples referred to f=1, relative aperture 2.8 and image angle 47 and 43 deg. respectively.