Here's how: 1  Stand with your feet shoulder-width apart and knees bent slightly. 2  Lean forward, placing your hands just above your knees. 3  Round your back so that your chest is closed and your shoulders are curved forward.  Then arch your back so that your chest opens and your shoulders roll 1  back. Repeat several times.
Typically this count is between 100,000 and 300,000 shutter actuations, with the latter limit associated with the EOS-1D models. In fact, the Camera Shutter Life Expectancy Database is a really neat user-based site for DSLR models of several brands, including Canon.
actuator. A mechanical, electrical, or hydraulic device, or their combination, used to effect some predetermined linear, rotary, or oscillating movement. An actuator essentially converts hydraulic or air pressure into mechanical force. Basically, there are two types of actuators: single-acting and double-acting. In the single-acting actuator, the piston moves in a single direction as a result of system pressure. In a double-acting system, the actuator's piston moves in either direction.