EV2: Shutter Speed
Nov 15th, 2006 by Larry
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If you read my first post on exposure value (EV) you know that shutter speed is one component. For most people the idea of shutter speed (unlike aperture) is easy to understand. Shutter speed is exactly what it sounds like it is; the speed of the shutter. It’s a designation of the amount of time the shutter is open and, except for very long exposures, is measured in fractions of a second. Consequently a shutter speed of 250 indicates that the shutter will be open for only one 250th of a second.
Shutter speed is set by the camera under normal conditions. This means that unless you take specific steps to control it, you probably don’t think about shutter speed very much. Shutter speed can be used creatively, however. It’s shutter speed that stops action and allows shots that show the beautiful patterns of droplets splashing. Shutter speed also allows blurring of motion to produce ribbons of light from cars moving along a highway, this meteor tail, or arced star trails revolving around the North Star.
Let’s say you want to take a picture of your kids sliding downhill on a toboggan. Do you want to see the toboggan and your children and their fingers and hair in perfect focus, or will that be too static to communicate the sense of fun and excitement? If so, slow the shutter speed and allow some amount of blurring. Knowing how much to slow the shutter is the most difficult part. It takes experimentation.
On the other hand, sometimes you want to stop the motion completely so normally invisible details are rendered in beautiful detail. This calls for the shutter to be open for a very short time as in this shot where chips of sunflower seed fly when bitten by a house finch.
If you are shooting in very bright light, short exposures are a must and you’ll be using very high shutter speeds. Conversely shooting at night often requires shutter speeds of several seconds or more. To make a trail of headlights you’ll need to expose for around eight seconds, for example.
More information can be found at Wikipedia and here.
–Larry