Shutter Speed
The shutter is fairly easy to understand. You can imagine it as a door which
opens and closes to let in the right amount of light. So do you want a fast
or slow shutter (if your camera gives you a choice)? A fast shutter allows
the camera to get a sharp picture of objects which are moving. A slow shutter
is more suitable for stationary subjects or if you want the subject to be blurred
to show that it's moving.
Shutter speeds are normally given as a fraction of a second e.g. 1/100 is one-hundredth
of a second. Many camera's will allow shutter speeds between a few seconds
(very slow) and say 1/4000 (very fast).
To understand how this affects your picture, imagine you take a photo of someone
running. In the space of a second they may run right across your picture in
which case they are going to be very blurred (which might be what you want).
Even 1/100 would probably look a bit blurred. At 1/4000 it's almost certain
to be sharp. So if you want a sharp image of a moving object use the fastest
shutter that you can. If you want a bit of blur slow it down until you get
the effect you're after.
But...the shutter speeds you can use depend how much light there is and how you've
set the aparture. If it's a really dull day there may simply not be enough
light around to get a photo with 1/4000 even with the aparture wide open (see below).
The choice for both shutter speed and aparture often end up being a compromise.
Examples
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Fast Shutter
- Freezes the motion of the plane as it takes off (and the propellers too) |
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Slow Shutter -
Shows motion and allows you to create nifty effects
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Shutter Priority
Most modern SLR cameras have a shutter priority mode.
On this setting you set the shutter speed that you want to get the effect you have
in mind and the camera adjusts the exposure itself just using the aperture.
Obviously, there's a limit to what the camera can do and it will usually warn you
if it can't get the exposure right for the shutter speed you've chosen.
Shutter priority is really useful for shooting things like birds which move quickly
and move in and out of shade. If you tried to set an SLR camera entirely mannually
the bird might well have gone by the time you've got the exposure right. Using
this mode you can set a fast shutter (to freeze the bird in motion) but not worry
about the changes in light as the subject moves about.
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