Abstract: A single lens reflux camera of the type in which actuation of a first electromagnet causes sequential operation of the diaphragm, mirror and shutter, and in which the start of the opening operation of the shutter is followed, after an electronically timed interval, by actuation of a second electromagnet which controls closing operation of the shutter. In one embodiment, a device for preventing faulty operation of the shutter includes a voltage detector responsive to the drop of voltage of a battery below a satisfactory operating level for preventing the first electromagnet from being actuated when the shutter button is depressed, and an arresting mechanism arranged upon detection of abnormal operation of the second electromagnet at the start of operation of the mirror to stop a mirror drive means from further movement which would otherwise cause actuation of the shutter release.