| 摘要 |
PURPOSE:To find the quantity of movement of a focusing lens accurately and speedily and to perform high-accuracy focusing operation by performing specific arithmetic operation by utilizing the quantity of defocusing of a photography system, the displacement position of the photography system, and various characteristic optical numerals that the photography system has. CONSTITUTION:The photography system 1 has a power variation system 12 and the focusing lens 11 and a focus detecting means 2 detects the quantity of defocusing from the expected image formation plane of the photography system 1 or a quantity equivalent to it. A storage part 3 provided in the photography system 1 is stored with various optical numerals characteristic to the photography system, e.g. two reference coefficients delta and N concerning the movement of the focusing lens. A power variation position detecting means 6 detects one of power variation areas which are divided having different ratios between the wide-angle and telephoto sides of the entire power variation range and an arithmetic means 4 calculates the expected quantity chi of movement of the focusing lens from the reference coefficients from the storage part 3, the quantity (d) of defocusing found by the focus detecting means 2, and a power variation signal from the power variation position detecting means 6. A driving means 5 drives the focusing lens 11 by a specific quantity on the basis of the arithmetic result obtained by the arithmetic means 4.
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