| 摘要 |
PURPOSE:To execute a correction without using an optical correcting means, etc. by deriving approximately an image height modulating straight line as a correction coefficient by executing a numerical operation of information on an output of a photodetector, and correcting a light quantity balance influenced by an image height of the photodetector output by using said line. CONSTITUTION:A luminous flux which has passed through an image forming optical system is led to the first and the second photodetector trains through a stripe mask, and a lateral shift of an optical distribution pattern corresponding to a shift quantity of a focus is generated on the photodetecting surface. Subsequently, basing on the output distribution of said first and second photodetector trains, a detection of a focusing state is executed, and a photodetecting sensor in which the stripe mask and the photodetector trains A, B are arrayed alternately is placed on a photoelectric converting part 28, and a coefficient for correcting a light quantity unbalance generated with regard to a direction of each photodetector train is derived from the output distribution of each photodetector train. This correction coefficient and the output distribution of each photodetector train are operated by an operating circuit 31, and a motor 2 is controlled by leading its output to a controlling circuit 34. |
