What are the shutter speeds?
The shutter speeds usually run between 1/30 sec. and 1/500 sec. A shutter speed wheel at the top of the camera controls the shutter speed. The different shutter speeds give you different possibilities: You can control the light amount/exposure time, and freeze the action. Thus by shooting at 1/500 sec. you can freeze moving action that would be blurred at 1/30 sec. if you are not using a tripod the it is better to use short speeds, like 250 or 500. To change aperture, just lift the ring about 3-5 mm and turn to desired speed.
