| 摘要 |
PROBLEM TO BE SOLVED: To provide a focus detecting optical system capable of excellent focus detection corrected in chromatic aberration and distortion, which has a precision not found in a conventional focus detecting system for the 135F or APS size and can meet the requirement for a small camera of novel design, and a camera provided with it. SOLUTION: The focus detecting optical system has a condenser lens L1 which has an image magnification mg satisfying the conditional expression (1) and is satisfying the conditional expression (2) near the planned focusing plane equivalent to the focusing plane of the photographing lens, a pair of aperture diaphragms S1, and a pair of re-focusing lenses L21 matching the aperture diaphragm S1 and satisfying the conditional expression (3). The conditional expression (1) is 0.45<¾mg¾<0.75, the conditional expression (2)0.75<¾R1/R2¾<1.25, and the conditional expression (3) R3/R4¾≤0.02. And, R1, R2 represent the curvature radius of the entrance and exit surfaces of the condenser lens respectively, and R3, R4 the curvature radius of the entrance and exit surfaces of the image re-focusing lens respectively. COPYRIGHT: (C)2004,JPO&NCIPI |
