This invention is directed to a camera in which an ordinary or normal photographing image-plane size, a photographing image-plane size narrower or smaller than the normal photographing image-plane size, for example, a panoramic size, and the like are changeable, the camera comprising a back closure openable and closable with respect to a camera body, an aperture arranged between a film and a photographing lens, for regulating an exposure range corresponding to the normal photographing image-plane size, a light shielding unit arranged between the film and the photographing lens and so arranged as to be movable between a saving position where the light shielding unit is saved (i.e. spaced) from the inside of the aperture so as not to interrupt an exposure luminous flux incident upon the aperture and a projecting position where the light shielding unit projects inwardly of the aperture to interrupt a part or substantially all of the exposure luminous flux, an operating unit for assigning the narrow photographing image-plane size, a detecting unit for detecting at least one camera operating condition including a power source condition of the camera, an opening and closing condition of the back closure, a forcible rewinding condition of the film and an exposure condition to a film surface, and a drive unit for driving the exposure unit, the drive unit driving the light shielding unit to the inward-most projected position or a saved position in spite of assignment of the operating unit in accordance with an output from the detecting unit.