| 摘要 |
PURPOSE:To perform automatic high-precision focusing by utilizing the symmetry of picture element deviation near both sides of a focusing position. CONSTITUTION:Intensity distributions of two subject images of the same subject 11 which are formed by pieces of luminous flux passed through different parts of an objective lens 15 are detected by image sensors 20A and 20B respectively. While either of the lens 15 and subject 11 is moved toward or away from the other, the coincidence or dissidence between intensity distribution signals of the detected subject images of the sensors 20A and 20B is detected to obtain two change points of coincidence to dissidence or dissidence to coincidence transition. Then, a focusing position is calculated from the two change point by a specific function and the lens 15 or subject 11 is moved to the focusing position to perform focusing operation.
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