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.
Also called film speed. the sensitivity of a film or paper to light, measured by an ASA or DIN index, which assigns low numbers to slow film and higher numbers to faster film. Also called shutter speed. the length of time a shutter is opened to expose film. the largest opening at which a lens can be used.