High speed wide angle objective lens system

摘要

An extremely high speed wide angle objective lens system, wherein a reducing Newtonian finder telescope is arranged in front of an objective lens group which produces a real image on an image plane. Rules or conditions are stated, and several specific examples are given. In many of the examples, the back focus distance is relatively large, thus making the lens system suitable for use with a mirror reflex camera where room is needed for swinging the reflex mirror.