What is shutter speed?
Shutter speed is the measurement (in fractions of a second)
of time the camera's shutter allows light
to strike the film or censor.
It is used to freeze action, create smooth waterfalls and
eliminate camera shake from the operator.
The standard shutter speeds include the following:
1s 1/2s 1/4s 1/8s 1/15s 1/30s 1/60s 1/125s 1/250s 1/500s
You'll notice that each speed is half that of the preceding
one. This is known as halving/doubling. Each speed either
halves or doubles the amount of time light allowed to
strike the film or sensor of the preceding speed. Modern
cameras are able to use settings in-between the above to
give greater exposure accuracy.
Most modern cameras can exceed 1/1000 of a second and can
often reach 1/8000s. Most SLR cameras also have a B (Bulb)
setting that allows you to hold the shutter open for as
long as you need.
To obtain acceptably sharp results from a telephoto lens
you should aim to use a shutter speed that is the
reciprocal of the lens focal length. In other words, if
you're using a 200mm lens then you should aim to use a
shutter speed of no less than 1/250s of a second. If using
a 500mm lens then 1/500s of a second should be used. This
is a rule of thumb for hand-holding the camera. If you
happen to have a tripod with you then you can use whatever
shutter speed you like.
The longer the shutter is held open the more likely you are
to blur the resulting image.