| 摘要 |
PURPOSE:To allow one lens system to function for focus detection on both active and passive bases by arranging the 1st optical splitter on part of an optical path and a lens system and the 2nd splitter in a branched optical path, and arranging focus detecting means of two active and passive systems behind the 2nd optical splitter. CONSTITUTION:When an object side is bright or when the object is relatively at a distance, luminous flux split by the 1st optical splitter 2 is passed through the lens system 6 to form an image and the majority of luminous flux within the visible range is reflected by the 2nd optical splitter 7 to form an object image on the surface of the 1st photodetection part 8; and the image formation state is measured to perform focus detection. When the subject side is dark or when the subject is at a short distance, luminous flux is emitted by a light source 9. The majority of infrared luminous flux of the light emitted by the light source is passed through the 2nd optical splitter 7 and projected on the object side through part 1 of a photography system. Luminous flux reflected by the object side is guided to the surface of the 2nd photodetection part 11 by a lens 10 for photodetection and the position of the reflected luminous flux is detected to perform the focus detection. |
