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.
There are three exposure parameters â aperture, time (shutter speed), and sensitivity (ISO), and in different modes these are each set automatically or manually; this gives 2 3 = 8 possible modes. For a given exposure, this is an underdetermined system, as there are three inputs but only one output.