| 摘要 |
PURPOSE:To obtain a range finding optical system without a movable part and with few parts in a single-lens reflex camera by arranging a split prism at the scheduled imaging surface of a camera lens and by arranging a light source and a photodetector behind a penta prism and symmetrically to an optical axis. CONSTITUTION:A camera lens system is composed of a camera lens 1, a reversible and movable mirror (neglected in the drawing), a focusing plate 3 prepared at the scheduled image surface. At the central part of the focusing plate, slipt prisms 3a, 3b are formed in a body. A finder is constituted with a penta prism 4 and an eyepiece 20. A range finding optical member consists of a pair of lenses 5a, 5b placed symmetrically to the optical axis and a prism, an image of a light emitting element 7 is imaged on a prism 3a through a lens 5a, and imaging a light reflected in imaged at a object 0 on a pair of photodetectors 8a, 8b through the prism 3b and the lens 5b. At the time of focussing, the amounts of received lights are equal and in the case of a behind pin or a front pin the amounts of received lights of elements 8a, 8b is increased. |
