When I think of shutter speed, the first thing that comes to mind is its use in controlling the amount of blur (or lack of it) in a picture containing moving objects. If you want a moving object to appear sharp in a shot then you require a faster shutter speed than if you were taking a stationery object. When deciding what the speed should be you will need to take into account the speed of the object, direction of movement & how big it appears in the frame (eg. objects moving across your line of sight will need higher shutter speeds than those coming towards you; ones that fill your viewfinder require faster shutters speeds than those which are smaller). You may of course, not want everything moving to be perfectly sharp, instead opting for a more artistic blur to emphasize their motion. This latter idea really comes into it’s own when photographing moving water (eg. rivers, waterfalls etc.) to create a more dream like picture.
Another use of shutter speed, even when taking pictures of stationery objects, is to counter the effects of ‘camera shake’. If the shutter speed is fast enough it will compensate for the slightest movement of your body producing blurred images. How fast the shutter speed needs to be depends upon a number of factors such as, if you’re using an image-stabilised lens, how windy it is but the most important factor is the focal length of the lens. The more you zoom in, the harder it is to keep your body sufficiently still to obtain a sharp image.
The minimum shutter speed should be ‘one over’ the focal length eg. with a 50mm lens use 1/50sec or faster.
Naturally, all this ‘camera shake’ compensation is mute if you use a tripod.
All the photos below were taken using Tv mode.