Abstract: A camera having means for regulating the exposure area of a frame of film has one operating member extending to the outside of the camera body and arranged to operate a regulating plate inside the camera body to move said plate between two positions. In a first position, as shown in the drawing, a full frame of film is exposed and a whole picture can be viewed through the viewfinder, and in the second position, the side areas of the viewfinder are shielded by the plate and a pair of opaque movable blades are moved to shield the exposure window from the sides so that only half of the film frame is exposed. At the same time as the regulating plate is moved from the first to the second position, a clutch device for controlling the film advance wheel is actuated, so that the wheel will rotate only one half cycle for each photograph to reduce the length of the wound film to one half of the length that is wound for whole frame photography.