Importance

Loading Importance Indicators...

Abstract

In a focus detecting device, an object's image formed on a prescribed image plane of a photo-taking lens is once again formed by a secondary imaging optical system disposed behind the prescribed image plane into two non-superposed object's images based on light flux portions symmetrically split relative to the optical axis of the photo-taking lens; light sensitive elements are respectively disposed in positions where these images of the object are re-imaged by the secondary imaging optical system; and an in-focus state of the photo-taking lens is arranged to be detected by detecting the relative positional relation of these reformed images of the object by means of these light sensitive elements. The focus detecting device includes light splitting means which is arranged in the secondary imaging optical system to split a light flux coming from the exit pupil of the photo-taking lens into a middle part portion and a peripheral portion. With this arrangement, an object's image which becomes necessary as the F-number of the exit pupil of the photo-taking lens varies or an object's image which permits simultaneous use of another detecting method in the device can be obtained by the secondary imaging optical system.

Loading the Abstract Image...

First Claim