| 摘要 |
PURPOSE:To always perform focus detection with the distance measuring visual field varied and that with the distance measuring visual field fixed with a high precision by specifying the arrangement of a first focus detecting system where the distance measuring visual field is varied and a second focus detecting system where the distance measuring visual field is fixed. CONSTITUTION:When two focus detecting systems are arranged on the image side of an objective lens 1, first and second focus detecting systems share a field lens 8 arranged in the vicinity of a predeterminate image forming surface of the objective lens 1. A first stop aperture 12a of the light receiving means in the first focus detecting system is arranged on the outside of second stop apertures 9a and 9b of the light receiving means in the second focus detecting system with respect to the optical axis, and the distance between the image space principal point of a field lens 8 and the first stop aperture 12a is set to a value longer than the distance between said image space principal point and second stop apertures 9a and 9b. Thus, focus detection with the distance measuring visual field varied and that with the distance measuring visual field fixed are always performed with a high precision whichever focal length the set objective lens has. |
