High speed lens having short back focus and compact rear member

摘要

A high speed lens of the type sometimes called a quasitelephoto lens, having a very short and compactly constructed rear member, and having a relative aperture in the range of about f/2 to f/1.4. The lens is intended particularly for installation in a 35 millimeter reflex camera. The back focus is sufficiently great to allow room for the swinging of a reflex mirror. The central space between the front member and the rear member is sufficiently large to allow room for installation of a diaphragm or an objective shutter, or both, in this space. Rules or conditions are stated which, if followed, will enable the production of lenses having the characteristics above mentioned, at the same time having a very high quality of photographic performance. Detailed data are given for eleven specific examples.