A sector drive assembly for a camera with reduced power consumption has a base plate having an aperture, one or more sectors capable of opening and closing the aperture, an electromagnetic actuator for driving the sectors, a drive force transmitting mechanism for transmitting a drive force of the electromagnetic actuator to the sectors, a first detecting unit for detecting when the sectors are open, and a second detecting unit for detecting when the sectors are closed, wherein the supply of power to the electromagnetic actuator is controlled based on signals from the first and the second detecting units.