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.
In your camera's viewfinder, a shutter speed of 1/4 is displayed just as 4. A shutter speed of 4 seconds is displayed as 4  (with a double quotes afterward to indicate whole seconds). Shutter speed is the amount of time that the camera is permitting light from the lens to hit the film or digital sensor.