Exposure control system
AssigneeCanon Kabushiki Kaisha
InventorsYukio Mashimo, Takashi Uchiyama, Kanehiro Sorimachi
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Abstract
In the exposure control system disclosed, a first photoelectric element responds to light from a scene to be photographed. A second photoelectric element is a spot sensor set to respond from a portion of the scene to be photographed. An exposure control circuit which is coupled to the first and second photoelectric elements controls the shutter and aperture on the basis of at least the relationship between the responses of the first and second photoelectric elements.
Claims41
An exposure control system for a camera capable of carrying film and has supplemental lighting means, comprising exposure forming means for regulating the aperture and exposure speed to which the film is to be subjected, first photoelectric means for responding to overall light from a scene to be photographed, second photoelectric means for responding to light from a predetermined portion of the scene to be photographed less than the overall scene, and exposure control means coupled to said first and second photoelectric means and said exposure forming means for controlling said exposure forming means to expose the film on the basis of at least the relationship between the response of said first photoelectric means and second photoelectric means.
An exposure control system of a camera mechanism for producing an appropriate exposure overall and to an object to be photographed in a flash photographing comprising a flash illumination means, exposure control means forming an exposure sequence by opening and closing operations and having a variable aperture, control circuit means having the first photoelectric conversion element for converting intensity of illumination of the main object in a scene to be photographed into a quantity of electricity, the second photoelectric conversion element for converting intensity of illumination of the remaining portions of the scene to be photographed into a quantity of electricity, a comparison circuit for connecting said first and second conversion elements, and a control circuit being connected with said comparison circuit for determining the operation of said exposure control circuit, an impedance member connected with said control circuit, an impedance value of said member being determined in response to the distance onto the main object portion among objects to be photographed and the guide number of said flash illumination means, said exposure control means being set by said control circuit to an aperture in response to the distance onto the main object portion, the guide number of said illumination means and the brightness of both the main object portion and the remainder of the scene as well being set to full opening and closing corresponding to the quantity of light of the remaining portions of the scene on the basis of said aperture.
A camera exposure control system for affording appropriate exposures on the basis of overall illumination and the illumination of an object to be photographed with flash, comprising flash illumination means, exposure control means for forming an exposure sequence by an opening and closing operation, said exposure control means including a variable aperture, control circuit means having a first photoelectric conversion element for converting the illumination of the main object in a scene to be photographed into an electrical quantity, said control circuit means including a second photoelectric conversion element for converting the intensity of illumination of the remaining portions of the scene to be photographed into a second electrical quantity, a comparison circuit connected to said first and second conversion element for comparing the outputs of said first and second conversion elements, and a control circuit connected with the output of said comparison circuit and coupled to said exposure control means for controlling the operation of said exposure control means, said control circuit including an impedance member the impedance value of which is determined in response to the distance of the main object to be photographed and the guide number of said flash illumination means, said exposure control means being set by said control circuit to an aperture in response to the distance to the main object being photographed, the guide number of said illumination means and the brightness of the main object portion and the remainder of the scene being set for opening and closing in correspondence to the quantity of light of the remaining portions of the scene on the basis of said aperture.
Dependencies are inferred from the claim text.