| 摘要 |
In a focus detecting device for a camera in which, from an object light passed through a focus plate removably provided on the image formation plane of a phototaking lens, a first image and a second image are formed by a pair of re-imaging optical systems with the in-focus condition of said phototaking lens with respect to an object is detected from the variations in position of said first and second images with respect to a pair of photoelectric converters disposed on or near the focal planes of said re-imaging optical systems, said focus plate being provided with a field lens, there are provided means for shielding, substantially symmetrically with respect to the optic axis of said phototaking lens, part of light beams forming said first and second images formed on said pair of photoelectric converters by said phototaking lens and said pair of re-imaging optical systems, and means for driving said shield means in response to the mounting of said focus plate onto the camera.
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