ABSTRACT
A large number of interesting photographic lenses have been designed since the end of the nineteenth century. This chapter describes only a few of them, but the reader may consult the interesting books by R. Kingslake, S. F. Ray, and Smith. In order to produce a good image over a large field of view, most photographic lenses are anastigmats. A lens is said to be anastigmat when it has a flat field free of astigmatism. In a photographic camera, the irradiance at the film or light image detector is directly proportional to the square of the entrance pupil diameter and inversely proportional to the square of the focal length. Asymmetrical anastigmats have also been designed with many different configurations. Some of the more important and interesting asymmetrical lenses are described. The Petzval lens is one of the oldest photographic lenses systematically designed. This lens consists of two achromatic doublets with the stop between them.
