A camera has a shutter release button that is held in an initial position while being not pressed, and is movable from the initial position to a full-pressed position via a half-pressed position. The camera is provided with first to third detectors for detecting that the shutter release button is in the initial position, in the half-pressed position and in the full-pressed position respectively. When the first detector detects that the shutter release button is displaced from the initial position, the shutter release button is considered to start being pressed down, so the camera starts preparatory operations for shooting, like photometry. When the second detector detects that the shutter release button reaches the half-pressed position, the camera completes the preparatory operations for shooting by carrying out aperture control and focusing. When the third detector detects that the shutter release button reaches the full-pressed position, the camera carries out an actual shutter release to write image data on a memory card.