| 摘要 |
PURPOSE:To correct a shift in image formation position resulting from the update of the focal length of the whole system speedily and automatically by providing a focusing correction control means which determines the driving direction of a focusing lens group and controls a focusing driving means so that the focusing lens group is driven to a focusing position according to the correction quantity for the focusing lens group. CONSTITUTION:An up switch 13, a down switch 14, and a driving direction decision part 15 are provided as a power variation direction indicating means which outputs a power increase indication signal for indicating the driving of a power varying lens group 2 from the shortest focal length side to the longest focal length side or a power decrease indication signal for the opposite driving from the power increase to a power variation driving means. Further, a focusing correction arithmetic part 11 and a focus control part 12 are provided as a focusing correction control means for controlling a focusing driving means which calculates the correction quantity for correcting the image formation shift from the focal length when the power varying lens group 2 is driven by the power variation driving driving means, determines the driving direction of the focusing lens group 2 with the outputs of power variation direction indicating means 13-15, and drives the focusing lens group 2 to the focusing position according to the correction quantity. Consequently, the image formation position shift resulting from the update of the whole system focal length is corrected speedily and automatically.
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