| 摘要 |
PURPOSE:To correct a shift in image formation position due to the update of the focal length of the whole system characteristic to a vari-focal lens by simple constitution stably at a high speed by driving a focusing lens group to a corrected focusing position according to a correction execution signal. CONSTITUTION:A comparative decision part 13 compares its internal set reference value with a correction quantity based on focal length information and outputs the execution signal GO, correction quantity Dfp, and focusing direction information when the correction quantity exceeds the reference value. Consequently, a focus control part 5 compares the output of a focus counter 6 with the correction quantity Dfp successively to drive the focus lens group 3. Then a variable power lens group 2 is driven and corrective focusing operation is performed when a shift quantity reaches a specific value. Then when an up switch 16 is turned on during said operation, the corrective focusing operation is carried on and the focusing lens group 3 is driven.
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