The term shutter speed describes the fraction of time that the shutter - a device that blocks light from reaching the film or sensor - is open for when you take a photograph. Shutter speed is normally quoted in fractions of second (e.g. 1/60) although in some situations, shutter speeds of over a second may be used.

What shutter speed you use depends on a number of factors. Firstly, it is the shutter speed together with the aperture that determine exposure. If you want to shoot with a certain aperture setting, perhaps a small one to create a large depth of field, this will restrict the range of shutter speeds that you can use. The higher the aperture setting (f/number), the smaller the hole in the front of the lens, and the longer the shutter speed that you will need to obtain a correctly exposed image.

Secondly, you may wish to adjust the shutter speed to achieve a particular effect. If you are shooting fast-moving action, such as a football match, you would normally choose a fast shutter speed to freeze the action. On the other hand, if you are shooting a waterfall, you might choose a slow shutter speed in order to blur the scene and create an artistic effect.

A third factor to account for is camera shake. If you are shooting without a tripod, then the longer the shutter speed the greater the chance that you will shake the camera during the exposure and produce a blurred photograph. There are two solutions: either use a tripod, or alternatively bear in mind this rough rule of thumb:

In other words, if the focal length of your lens is 50mm, then keep the shutter speed set to 1/50s or quicker. Remember that most digital cameras allow you to change the ISO rating each time you take a picture. If there is not enough light to shoot at the shutter speed you wish to, try increasing the ISO.