| 摘要 |
PURPOSE:To enable highly accurate focus detection whatever brightness a photographic lens in use has by constituting a stop which is mounted in front of a secondary optical system according to the brightness of the photographic lens in use by using a stop late and a support member, and constituting those respective elements properly. CONSTITUTION:The pupil 7 of an objective 1 is divided into plural areas, light quantity distributions regarding a subject image are detected by using pieces of luminous flux passing through the respective areas, and the relative position relation of those light quantity distributions is found to detect the focusing state of the objective 1. Then the secondary optical system 4 which forms the couple of light quantity distributions regarding the subject image and the stop 6 while limits the luminous flux passing through the secondary optical system are provided and the stop has the movable stop plate 26a provided with stop openings 6a - 6c and the fixed support member 26b. Then the stop plate is displaced by the support member to limit luminous flux incident on the secondary optical system. Consequently, the best focus detection corresponding to the brightness of the photographic lens becomes possible. |
