A camera has a shutter release button, held in an initial position, that is movable from the initial position to a full-pressed position via a half-pressed position. The camera has three detectors for detecting that the shutter release button is in the initial, half-pressed and full-pressed positions respectively. When the first detector detects that the shutter release button is displaced from the initial position, it is determined that the shutter release is being activated, so the camera starts preparatory operations for shooting. When the second detector detects the shutter release button in the half-pressed position, the camera completes preparatory operations for shooting. When the third detector detects that shutter release button in the full-pressed position, the camera carries out an actual shutter release to write image data on a memory card.