Photometric device

A light-integrating photometer for receiving light from a scene having a background portion, a foreground portion, and a central portion and determining the duration of a film exposure interval for the scene, said photometer comprising:

• a photo-responsive means for receiving a light from a scene, said photo-responsive means including a first photo-responsive portion adapted to receive the light reflected from the foreground portion of the scene and provide a first electrical signal responsive thereto, a second photo-responsive portion adapted to receive the light reflected from the background portion of the scene and provide a second electrical signal responsive thereto, and a third photo-responsive portion adapted to receive light reflected from the central portion of the scene and provide a third electrical signal responsive thereto;
• first electronic circuit means coupled to said first and said second photo-responsive portions for selecting the maximum electrical output of said first and said second electrical signals and providing a time-integrated output of the so-selected signal;
• second electronic circuit means coupled to said third portion of said photo-responsive means for providing a time-integrated output of said third electrical signal;
• third electronic circuit means coupled to said first and second electronic circuit means for providing an indication signal that determines the duration of the film exposure interval when the outputs of said first and said second electronic circuit means correspond to a predetermined signal relationship.

An exposure control system for controlling the exposure interval of a photographic camera of the type having a shutter means that is adapted, upon initiation of a film exposure interval, to admit light from a scene to be photographed into the camera to expose photographic film within the camera and which is adapted to terminate the exposure interval in response to a shutter close command signal, said system comprising:

• a photo-responsive means for receiving light from the scene to be photographed, said photo-responsive means including a first photo-responsive portion adapted to receive the light reflected from the foreground portion of the scene and provide a first electrical input responsive thereto, a second photo-responsive portion adapted to receive the light reflected from the background portion of the scene and provide a second electrical output responsive thereto, and a third photo-responsive portion adapted to receive light reflected from the central portion of the scene and provide a third electrical output responsive thereto;
• first electronic circuit means coupled to said first and said second photo-responsive portions for selecting the maximum electrical output of said first and said second electrical outputs;
• and
• second electronic circuit means coupled to said third photo-responsive portion and said first electronic circuit means for providing a shutter close command signal responsive to said third electrical output and said so-selected maximum electrical output of said first and said second electrical outputs, the exposure indication being increased when the illuminance of the light incident on said so-selected photo-responsive portion as indicated by said so-selected maximum electrical output exceeds the illuminance incident on said third photo-responsive portion as indicated by said third electrical output and the film exposure indication being decreased when the illuminance of the light incident on said third photo-responsive portion as indicated by said third electrical output exceeds the illuminance of the light incident on said so-selected photo-responsive portion as indicated by said so-selected maximum electrical output.

An exposure control system for controlling the exposure interval of a photographic camera of the type having an integrating shutter means that is adapted, upon initiation of a film exposure interval, to admit light from a scene to be photographed to a film plane in the camera and to a photometer in correspondence with the scene light admitted to the film plane, which shutter means is adapted to terminate the exposure interval in response to a shutter close command signal, said system comprising:

• a photo-responsive means for receiving light from the scene to be photographed in correspondence with the scene light received by the camera photometer, said photo-responsive means including a first photo-responsive portion adapted to receive the light reflected from the foreground portion of the scene and provide a first electrical output responsive thereto, a second photo-responsive portion adapted to receive the light reflected from the background portion of the scene and provide a second electrical output responsive thereto, and a third photo-responsive portion adapted to receive light reflected from the central portion of the scene and provide a third electrical output responsive thereto;
• first electronic circuit means coupled to said first and said second photo-responsive portions to select the maximum electrical output of said first and said second electrical outputs;
• and
• second electronic circuit means coupled to said third photo-responsive portion and said first electronic circuit means to provide a shutter close command signal responsive to said third electrical output and said so-selected maximum electrical output of said first and said second electrical outputs, the exposure indication being increased when the illuminance of the light incident on said so-selected photo-responsive portion as indicated by said so-selected electrical output exceeds the illuminance incident on said third photo-responsive portion as indicated by said third electrical output and the film exposure indication being decreased when the illuminance of the light incident on said third photo-responsive portion as indicated by said third electrical output exceeds the illuminance of the light incident on said so-selected photo-responsive portion as indicated by said so-selected electrical output.

A photographic exposure control system for a photographic camera of a type having shutter means adapted, upon initiation of a film exposure interval, to admit light from a scene to be photographed to a film plane in the camera and to an averaging photo-responsive cell located to receive scene light in correspondence with the scene light admitted to the film plane, said exposure control system comprising:

• a first photo-responsive means for receiving light from the foreground portion of the scene to be photographed and for providing a first output signal responsive to the light from the foreground portion;
• a second photo-responsive means for providing and receiving light from the background portion of the scene to be photographed and for providing a second output signal responsive to the light from the background portion;
• a third photo-responsive means for receiving light from the central portion of the scene to be photographed and for providing a third output signal responsive to the light from the central portion;
• selector electronic circuit means coupled to said first and said second photo-responsive means for providing an output signal that is responsive to the maximum signal of said first and second signals;
• and
• exposure interval determining circuit means for providing a corrected shutter close command signal to terminate the exposure interval, said exposure interval determining circuit means being coupled to said third photo-responsive means and said selector electronic circuit means for providing a shutter close command signal corrected in response to said third electrical output and said so-selected maximum electrical output of said first and said second electrical outputs, the corrected shutter close command signal causing an increase to the film exposure when the illuminance of the scene light incident on said so-selected photo-responsive means as indicated by said so-selected output signal exceeds the illuminance incident on said third photo-responsive means as indicated by said third output signal and a decrease to the film exposure when the illuminance of the scene light incident on said third photo-responsive means as indicated by said third output signal exceeds the illuminance of the light incident on said so-selected photo-responsive means as indicated by said so-selected output signal.