An ACC system includes a controllable amplifier having an input coupled to receive a chroma input signal and an output for providing an chroma output signal of controllable amplitude. The lens barrel unit is covered with a front cover cylindrical member connected to the front cover, and a front exposed portion of the front cover cylindrical member is covered with an exterior cylindrical member as a detachable metal cylindrical member. The valve may be movable to fill chambers of the crowd cylinder with fluid pressurized by the pump and to drain the chambers of the crowd cylinder to cause extension and retraction of the crowd cylinder.