Abstract This specification discloses a focus detector device which utilizes the fact that when a target image is formed in focus on the surface of a photoelectric element such as CdS cell or the like through an objective lens the resistance of the photoelectric element is maximum and when the formed image is out of focus the resistance of the photoelectric element is decreased. At least one focusing light-receiving element is disposed in the optical path provided by the objective lens with a focusing lens interposed between the element and the objective lens. Means for limiting a light beam passed from the target or object of the photoelectric element is provided to control the amount of light so as to cause a predetermined brightness of the object light to be received by the photoelectric element. A second photoelectric element is provided to control the diaphragm of the objective lens and a second auxiliary diaphragm in front of the focusing phtotelectric element. The photoelectric element may be located either substantially conjugately with or forwardly and rearwardly of a secondary real image plane provided by the objective lens with respect to the focusing lens.
A single lens reflex camera having a photometric detector comprising in combination, a. a photographing objective with an aperture means having a fully opened and a stopped down condition; b. disphragm presetting means for controlling said aperture means; c. a photoelectric element receiving light coming through said photographing objective at its fully opened aperture condition and producing a signal in response to an object to be photographed; d. focus detector means including a photo-detector which receives light coming through said photographing objective at its fully opened aperture condition and through an auxiliary aperture means disposed between said photographing objective and the photo-detector along the path of said light; e. control means receiving the signal from said photo-electric element to control said auxiliary aperture means as well as said diaphragm presetting means; and f. a focus adjusting means for positioning said photographing objective at a position in which said focus detector means distinguishes a focused condition.
Claim 2
Dependent Claim
155 words
A single lens reflex camera having a photometric detector comprising in combination, a. a photographing objective with an aperture means having a fully opened and a stopped down condition; b. disphragm presetting means for controlling said aperture means; c. a photoelectric element receiving light coming through said photographing objective at its fully opened aperture condition and producing a signal in response to an object to be photographed; d. focus detector means including a photo-detector which receives light coming through said photographing objective at its fully opened aperture condition and through an auxiliary aperture means disposed between said photographing objective and the photo-detector along the path of said light; e. control means receiving the signal from said photo-electric element to control said auxiliary aperture means as well as said diaphragm presetting means; and f. a focus adjusting means for positioning said photographing objective at a position in which said focus detector means distinguishes a focused condition.
Claim 3
Dependent Claim
19 words
A single lens reflex camera according to claim 1, in which said focus detector means is of contrast-dependent characteristic.
Claim 4
Dependent Claim
32 words
A single lens reflex camera according to claim 1, wherein said focus adjusting means comprises an electric drive circuit responsive to electric signals produced by said photo-detector of said focus detector means.