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AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorsKazuo Nakamura, Katsuhiko Miyata, Seijiro Tokutomi
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In a single lens reflex camera a focus detecting device is provided to identify or control the in-focus condition of a lens. The detecting device operates on the same principle as that used in visual focusing, namely the bringing together of a split image or the observation of the clarity of an image or both. A group of photo-electric light detecting elements is positioned to receive a part of the object's image, which part corresponds to that watched by the photographer in determining an in-focus condition. For split image focusing the group is divided into two lines of elements located adjacent to and on opposite sides of the line splitting the image. Each line of elements effectively measures the spatial light intensity impinging thereon. When the spatial light intensity detected by both lines are the same, an in-focus condition is detected. For image clarity focusing the adjacent elements of a line of photo electric elements are connected so as to subtractively combine their photo current outputs. Thus a maximum output is achieved when the image has maximum clarity. A combination of both techniques is particularly suitable for providing increased accuracy of detection.
In a single lens reflex camera of the type having a reflecting mirror for directing light towards a finder optical system during pre-photography operation, a focusing plate positioned to receive said reflected light, a pentaprism positioned to receive light passing through said focusing plate, and a finder optical system positioned to receive light reflected from the surfaces of said pentaprism, whereby said camera can be focused by a photographer adjusting a lens system and observing an object's image through the finder optical system, the improvement characterized by,
A single lens reflex camera of the type having a mirror for reflecting light from an object after passing through a lens system, a focusing plate to receive said reflected light, a pentaprism, and finder optical means for permitting viewing of the image of said object by a photographer whereby visual determination of focusing is possible, and a pair of wedge shaped prisms located at a position optically equivalent to a film frame position in said camera, for splitting said object's image into a first half image and a second half image separated by a center line, the improvement characterized by;
Dependencies are inferred from the claim text.