| 摘要 |
PURPOSE:To make focusing operation easily without using a specially built camera body or interchangeable lenses by moving a whole or a part of an image forming optical system and a light splitting device in the direction of an optic axis. CONSTITUTION:Light entered an interchangeable lens 3 forms an image on the film face 2a of a camera body 2 through a rear conversion lens 1, and a part of the light is reflected by a light splitting plane of a light splitting prism 12 and forms an image on a photodetecting element 15 through a deflecting prism 13. As the face of the element 15 and the film face 2a are placed at optically conjugate positions, the focused state can be detected by the photodetecting element 15 by moving a whole or a part of lens group 1. Accordingly, the smooth focusing operation can be made by fixed force without moving a large and heavy interchangeable lens and can be made suitable as an automatic focusing device. |
