Camera controls for coupled and non-coupled objectives

Claim 1

In a single lens reflex camera adapted to use interchangeable objectives of the coupled and non-coupled type, and having a photosensitive means for measuring light after the light has travelled through a selected objective which is mounted on the camera, manually operable shutter-tripping means movable by the operator from a starting position to a shutter-tripping position and automatically returning to said starting position when released by the operator, electrical circuit means electrically connected with said photosensitive means for automatically determining the exposure time, said electrical circuit means including a main switch means having with respect to said shutter-tripping means a position which closes said main switch means and thus said electrical circuit means for energizing the latter upon movement of said shutter-tripping means away from said starting position thereof toward said shutter-tripping position thereof, releasable retaining means coacting with said main-switch means for retaining the latter in its closed position after said shutter-tripping means is released for return to its starting position until the shutter closes, said releasableretaining means responding automatically to closing of the shutter for releasing said main switch means for return to its open position, said electrical circuit means further including a variable resistor means for coacting with a coupled objective to introduce into said electrical circuit means a resistance value in accordance with a preselected diaphragm setting when a coupled objective is mounted on the camera, manually operable switch means forming part of said electrical circuit means and having a fully-open diaphragm position connecting said variable resistor means into said electrical circuit means in series with said photosensitive means and a stopped-down diaphragm position connecting said photosensitive means into said electrical circuit means while disconnecting said variable resistor means from said electrical circuit means, and control means for automatically opening said main switch means to terminate operation of said electrical circuit means upon release of said shutter-tripping means for return to its starting position in the event that said manually operable switch means has not been displaced to its stopped-down diaphragm position when a non-coupled objective is mounted on the camera, so that in the latter event the equivalent of a bulb exposure is made.