| 摘要 |
PURPOSE:To make correct focus detection possible despite the change in the exit pupil distance of a photographic lens by such constitution wherein plural photoelectric element pairs for detecting focal length are provided and one kind of the photoelectric pair is selected according to the exit pupil distance of the photographic lens. CONSTITUTION:The movable contact of a variable resistance 102 stops at the position corresponding to the full aperture F value of a photographic lens and when the full aperture F value is <=1.2, <=2.5, <=3.5 and >=4, comparators 103- 106 are made to Hi successively with voltage dividing resistances 107-111. When the full aperture F value is <=1.2, an LED 116 is flickered with an OR gate 113 and an AND gate 130, whereby the infeasibility of automatic focusing operation is announced. When the full aperture F value is 1.4-2.5, the output of an OR gate 114 goes to Hi without depending on the signals from a variable resistance 17 interlocking to the rate of extension of the lens and a comparator 120, and a control system 101 selects one of plural photoelectric element pairs via an AND gate 115. Thereafter, the correct focusing detection is accomplished in the same manner despite the change in the exit pupil distance of the photographic lens. |
