Shutter speed refers to the time it takes for the shutter to open and close, and is a critical component in determining correct exposure, as well as the creative look of the image.
Shutter speeds are always expressed in fractions of a second. For example, 1/1000 of a second would be a fairly fast shutter speed, and would freeze a moving subject. On the other hand, ½ a second would be quite a slow shutter speed, and would create blur in the image – either by a subject moving, or the camera itself being moved. Generally speaking, the better the camera, the faster you can set the shutter speed.
Faster shutter speeds are typically used in sports photography, or any situation where you want to create a sharp, blur-free image. On the other hand, slower shutter speeds are used when you want to intentionally blur a subject to capture the movement, such as with exploding fireworks.
Commonly, shutter speeds are adjusted in increments that have a halving or doubling relationship, ie., every time you adjust the shutter speed, you are either halving the shutter speed, or doubling it. As with adjusting aperture – or ISO Speed for that matter – these increments are known as ‘stops’.
The important thing to bear in mind with shutter speed is that whenever you increase the shutter speed by a full ‘stop’, you are halving the amount of light that passes through to the imaging sensor. To compensate, you would need to increase the size of the aperture, or increase the ISO speed by a full stop. Be aware that this will change the image, either by narrowing the depth of field, or by increasing grain in the image.
The job of the photographer therefore is to balance shutter speed, aperture
size, and ISO
Speed, to get the creative outcome they desire.