초록 ▼

Focus detecting device comprises a focus detecting optical system for guiding the light from an object onto a focus detecting plane, focus detecting means for identifying the focusing state from the image of the object formed on the focus detecting plane, means for generating a signal corresponding

Focus detecting device comprises a focus detecting optical system for guiding the light from an object onto a focus detecting plane, focus detecting means for identifying the focusing state from the image of the object formed on the focus detecting plane, means for generating a signal corresponding to the controlled actual F-number of the photographic optical system, means for generating a correction signal corresponding to the displacement of the optimum image plane of the photographing optical system according to the change of the controlled F-number, and means for correcting the output signal of the focus detecting means according to the correction signal.

대표청구항 ▼

In a camera system having an interchangeable lens barrel including therein a photographic optical system for positioning an optimum image plane of an object to be photographed in coincidence with a film plane, said optical system having optical characteristics in which the position of the optimum im

In a camera system having an interchangeable lens barrel including therein a photographic optical system for positioning an optimum image plane of an object to be photographed in coincidence with a film plane, said optical system having optical characteristics in which the position of the optimum image plane varies in the direction of the optical axis depending on the F-number of the photographic optical system, and wherein a diaphragm aperture of the photographic optical system is reduced to a controlled F-number in response to a shutter releasing operation, an improvement comprising: (a) a detecting optical system which is located rearwards of said photographic optical system for positioning the optimum image plane of the object on a predetermined surface, the detecting optical system having a fixed F-number; (b) focal point detecting means for detecting the positional relation in the optical-axis direction between said predetermined surface and the optimum image plane of the object through said detecting optical system based upon a focused condition where the image of the object is formed on said predetermined surface, the focal point detecting means generating a positional signal representing the detected positional relation; (c) means for detecting said controlled F-number of said photographic optical system to produce an F-number signal dependent upon the detected F-number; (d) optical characteristics detecting means for detecting said optical characteristics to produce an optical characteristic signal dependent upon said detected optical characteristics; (e) means for producing a distance signal representing the distance in the optical-axis direction between the optimum image plane of the object positioned by said photographic optical system at the controlled F-number and said film plane, based upon said F-number signal, said optical characteristic signal and said fixed F-number of said detecting optical system, when the optimum image plane positioned by the detecting optical system is substantially coincident with said predetermined surface; and (f) means for correcting said positional signal to a signal indicating positional relation in the optical-axis direction between said optimum image plane positioned by said photographic optical system and said film plane dependent upon said distance signal.