Abstract: An exchangeable lens photographic camera of automatic focussing type capable of focussing objects between a minimum and an infinite focussing distance. The camera has an exchangeable lens exchangeable in the camera body. The lens has a first switch providing a signal associated with focussing an object at the infinite distance, and a second switch providing a signal associated with focussing an object at the minimum distance. A focussing motor is coupled to the lens for moving the lens for focussing objects lying between the minimum and infinite distances. A first pair of contacts coupled between the exchangeable lens and the camera body transmits therebetween signals indicating the presence and direction of rotation of the focussing motor. A second pair of contacts, coupled between the exchangeable lens and the camera body, transmits the signals produced by the first and second switches from the exchangeable lens to the camera body.

Abstract: A photographic camera of automatic focussing type capable of focussing objects between a minimum and infinite distance. A focussing motor is coupled to a movable objective lens for moving the lens for focussing an image of an object to be photographed. A photoelectric focussing detector has a photoconductive element responsive to light rays passing through the objective lens. The photoconductive element provides a maximum response when an image of the object formed on the photoconductive element is in the focussed condition. A first electrical circuit determines the direction of movement of the focussing motor for moving the objective lens to focus the object image. A responsive zone is defined within which the output of the detector varies in accordance with the position of the objective lens, and a non-responsive zone is defined away from the responsive zone and within which the output of the detector is invariant independent of the position of the objective lens.