| 摘要 |
PURPOSE:To enable focusing to be performed accurately irrespective of the space frequencies of the subject by constituting the specified circuits in such a manner that the focusing is determined by the extreme value of the sum of the absolute value of the difference between the output mean value of the photodetector group for focusing detecting and the outputs of the respective photodetectors. CONSTITUTION:A photodetector group PSA is placed on the imaging film plane of a taking optical system or in a position equivalent to this. The outputs s1-sn from the respective photodetectors are subjected to addition averaging operations, and the mean output Si inputs to a differential detector DIF. On the other hand, the outputs s1-sn of the respective photodetectors inputting to the differential detector DIF are adjusted to suitable values with an amplifier AMP. The differential outputs u1-un between Si and of the differential detector and s1-sn are added in an adder ADD via a rectifier PCT, whereby an output Z is obtained. The focusing position is obtained in the position where Z assumes an extreme value when the taking optical system is displaced. Thereby, the focusing may be made accurately irrespective of the space frequencies of the subject. |
