| 摘要 |
PURPOSE:To obtain the extent of moving of a focusing lens at high accuracy and to speedily attain a highly accurate focusing by executing the prescribed arithmetic with the aid of the defocused extent of a photographing system and optical numerics inherent to the photographing system. CONSTITUTION:A focus detecting means 2 detects a defocused extent from the expected image forming plane of the photographing system, or the out-of- focus extent equivalent to the defocused extent. The optical numerics inherent to the photographing system such as reference coefficients regarding the movement of the focusing lens are stored in a memory part 2 installed in the photographing system 1. From the reference coefficients in the memory part 3 and the defocused extent DELTAd obtained by the focus detecting means 2, the 1st arithmetic means 4 obtains a moving coefficient Sd corresponding to sensitivity when a focusing lens should be moved, and calculates a length (x) by which the focusing lens should be moved. On the basis of the arithmetic result obtained by the 1st arithmetic means 4, a drive means 5 moves the focusing lens by the prescribed length. Thus focusing can be speedily made at high accuracy. |
