Lighting type bright frame finder

Abstract

A lighting type bright frame finder has as objective lens having a negative focal length; an eyepiece having a positive focal length; a frame; and a joining prism joined through a half mirror. An optical path from the frame to the eyepiece is formed by arranging the joining prism such that the half mirror is located between the objective lens and the eyepiece. The lighting type bright frame finder is constructed such that a visual field image is overlapped with a frame image formed by only the eyepiece so as to observe these images. The focal length f.sub.e of the eyepiece, a distance E from an eye pupil side lens face of the eyepiece to an eye pupil face, and a maximum emitting angle .theta. satisfy the following condition (1). f.sub.e /(E.multidot.tan.theta.)<7.5 (1) In this lighting type bright frame finder, the number of constructional lenses can be reduced and the finder can be made compact. Other lighting type bright frame finders are also shown.

Dependencies are inferred from the claim text.