| 摘要 |
PURPOSE:To enable focus detection of high accuracy to be performed with eash by providing the optical system which is so constituted that the both of a detection system by contrast change and a detection system by an image coincidence system are possible and that with respect to the detection system of the image coincidence the sharpness of the subject image is maintained sufficiently. CONSTITUTION:The subject 1 is confirmed by the photographer's eyes 15 by way of a photographing lens 2, total reflecting mirror 3 having half mirrors 4, 5, 5', focal plate 11, condenser lens 12, pentagonal prism 13 and eyepiece 14. On the other hand, the light passed through the half mirrors reaches three groups of photoelectric transducer groups 9, 10, 10' where the total reflecting mirror 6 mounted at a right angle to the total reflecting mirror 3 is installed in the position equivalent to the film plane 8 by way of total reflecting mirrors 7, 7' tilted symmetrically in the directions mutually opposite therefrom. The subject images formed on the element group 9 assume the largest contrast when the focus is matched and by obtaining the correlation function of the two outputs from the outputs from the element groups 10, 10', the out-of-focus amount and the before and behind the focus position may be judged. |
