| 摘要 |
PURPOSE:To make accurate, speedy automatic focus adjustment by arranging focus detectors in an image plane in an expected focus plane, and selecting the detector with the best contrast for the automatic focus adjustment. CONSTITUTION:One of light beams which are transmitted through a fiche film F is reflected by a half-mirror 52 and projected on a screen 6 and other optical paths are transmitted through the mirror 52 and reflected by a reflecting mirror 53 to reach the focus detectors 54a-54c. The detectors 54a-54c are provided with three CCDs respectively and detect a focus state from a difference in contrast. The detector having the best contrast is selected among those detectors 54a-54c and a specific CPU is used to make the automatic focus adjustment. Consequently, the proper adjustment is made in a wide focus area and the best detector is selected for the speedy automatic adjustment. |
