Focus detecting system detecting position of images formed from the center and periphery of the optical axis

摘要

A focusing detecting system for discriminating a focusing state of an object lens by detecting a relative positional relation of a plurality of object images formed by light fluxes from the object lens, by photo-sensing means is disclosed. A plurality of object images are formed based on a light flux from a center area of the object lens around an optical axis and a plurality of object images are formed based on a light flux an area in the periphery of the center area around the optical axis, by optical means disposed behind an image plane of the object lens. Light shielding means having a plurality of slits is disposed near the image plane. By those means, a state is which the object images based on the light fluxes from the center area of the object lens around the optical axis and the peripheral area are detectable and a state is which the object images based on only the light flux from the center area of the object lens around the optical axis is detectable are discriminated.