| 摘要 |
PURPOSE:To detect a focusing state with high accuracy at all times by lighting a photodetector array uniformly after an image formation optical system a pupil splitting means, and the photodetector array are assembled, and calculating a correction coefficient according to the outputs of 1st and 2nd groups of photodetecting elements so that the outputs come to equal to each other. CONSTITUTION:When the photodetector array is illuminated uniformly through the image formation optical means 11 and pupil splitting means 12, the correction coefficient is calculated according to the outputs of the 1st and 2nd groups of photodetectors 13 so that the outputs come to equal to each other, then written in a memory previously. Then when actual focus detection is performed, the correction coefficient which is stored previously in the memory is used to correct the output of the photodetector array. Unbalance based upon the influence of the image height of the quantity of light made incident on the photodetector array and the relative position shift between the pupil splitting means 12 and photodetector array can, therefore, be corrected effectively. Consequently, the focus state can be detected with high accuracy at all times and an optical system which uses no correcting lens can be used, so the optical system is simplified and reduced in size and cost. |
