Automatic focusing apparatus
First Claim
1. A focus detecting apparatus that includes an optical system having a group of focusing lenses, and means for measuring a defocus amount for an image of a specific object formed by said focusing lens group, comprising:
- means for determining a contrast of said image of said specific object; and
means for selecting a defocus amount such that, when said contrast determining means determines that said contrast of said specific object image is not low, said measured defocus amount is selected, and when said contrast determining means determines that said contrast of said specific object defocus amount is low, said defocus amount measuring means operates to re-measure said defocus amount, so that said re-measured defocus amount is compared with a previously obtained defocus amount to select a smaller defocus amount.
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Accused Products
Abstract
A focus detecting apparatus that includes an optical system having a group of focusing lenses. An object distance measuring device measures a defocus amount for a specific object imaged by the optical system. A focus judging device determines a focus state in accordance with a measurement of the object distance measuring device. A lens driver then drives the focusing lens group to a focal position, in accordance with the amount of defocus, wherein the apparatus includes a controller for repeatedly operating the object distance measuring device and the lens driver. A moving object judging device determines that the specific object is a moving object when the focus judging device determines an out-of-focus state more than one time during the repeated operations.
65 Citations
10 Claims
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1. A focus detecting apparatus that includes an optical system having a group of focusing lenses, and means for measuring a defocus amount for an image of a specific object formed by said focusing lens group, comprising:
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means for determining a contrast of said image of said specific object; and means for selecting a defocus amount such that, when said contrast determining means determines that said contrast of said specific object image is not low, said measured defocus amount is selected, and when said contrast determining means determines that said contrast of said specific object defocus amount is low, said defocus amount measuring means operates to re-measure said defocus amount, so that said re-measured defocus amount is compared with a previously obtained defocus amount to select a smaller defocus amount. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A focus detecting apparatus that includes an optical system having a group of focusing lenses, measuring device that measures a defocus amount for an image of a specific object formed by said focusing lens group, comprising:
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a contrast device that determines a contrast of said image of said specific object; and a selecting device that; selects said measured defocus amount when said contrast device determines that said contrast of said specific object image is not low; and re-measures said defocus amount so that said re-measured defocus amount is compared with a previously obtained defocus amount in order to select a smaller defocus amount when said contrast device determines that said contrast of said specific object defocus amount is low. - View Dependent Claims (8, 9, 10)
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Specification