Iris mechanism in body of interchangeable-lens camera

Claim 1

In a camera having a camera body, a film holder in said body adapted to hold film in a desired position during exposure, lensreceiving means in the camera body adapted to hold any one of a plurality of lenses in spaced relation to the film holder, a shutter adapted to move between a closed position in which said shutter protects film in the film holder from light passing through a lens in the lens-receiving means and an open position in which the shutter permits the passage such light, and shutter control means for moving the shutter from the closed to the open position when said shutter control means is activated, the improvement comprising a plurality of interchangeable lenses of the type that has no adjustable iris and is therefore of a fixed f-value, said lenses having different focal lengths but the same f-value and said lenses being adapted to be held by the lensreceiving means; an iris located within the camera body in the light path between the position occupied by the rear element of a lens in the lens-receiving means and the film holder, said iris being movable between a wide-open position and any one of a plurality of partially shut positions, said iris when in a partially shut position partially occluding the light path between the lens and the film holder, through-the-lens exposure meter means for measuring scene brightness by measuring the intensity of light which has passed through a lens held in the lens receiving means and through the iris, and control means linking the exposure meter means to the iris for moving the iris from the wide-open position to a desired partially shut position selected in accordance with the intensity of light measured by the exposure meter, said movement occurring immediately before the activation of the shutter control means.