| 摘要 |
PURPOSE:To approximately equalize optical characteristics of an AF optical system and an image pickup optical system, to improve the reliability of the AF precision and to make an AF device small-sized and low-cost by arranging a field lens, which is one element of an optical characteristic approximately equivalent to the optical characteristic of the image pickup optical system and has a prescribed thickness, in the vicinity of a face approximately equivalent to the image surface of a photographic lens. CONSTITUTION:An optical means 27 has a field lens 21 in the vicinity of a face equivalent to the image surface of a photographic lens 25, and the field lens 21 has a thickness to give an optical characteristic approximately equivalent to the optical characteristic of a parallel plate glass arranged in the image surface side of the image pickup optical system. Thus, it is unnecessary to adopt the mechanism constitution where the field lens and a correction glass are supported independently of each other, and the AF device is miniaturized with respect to space, and the number of parts of supporting members and the man-hour for assembling are reduced to reduce the cost. |
