| 摘要 |
PURPOSE:To enable an active type autofocus mechanism to adapt itself to a shift in the position of an object from an optical axis by averaging plural detected positions of photodetected images and performing position detection. CONSTITUTION:For example, when spot light from a projection part 1 is projected on the object in a partial missing shape, 1st and 2nd photodetection parts 2 and 3 generate photoelectric currents IA1 and IA2, and IB1 and IB2 corresponding to the displacement positions of photodetected images projected there. Then those photoelectric currents are inputted to an arithmetic part, which performs prescribed arithmetic processing based upon a distance measurement expression to calculate the distance L between the surface of a film 5 and the subject 4. Consequently, this mechanism performs high-accuracy distance measuring operation by adapting itself accurately to the shift in the position of the subject 3 from the optical axis. |
