Shutter lag time simply means the time it takes from when you press the shutter button to when the camera actually records the picture. Although the shutter lag time often is less than one second, that small amount of time can be just enough to cause the subject to move out of frame and cause you to miss a great photo.
Modern DSLRs suffer far less with this problem, but some small traces of lag time can sometimes be noticed. Compact cameras, especially inexpensive ones, often suffer from shutter lag.
There are three distinct components of shutter lag, which results in problems with slow cameras.
- Autofocus lag. This refers to the amount of time from when you press the shutter button halfway to when the camera finds an autofocus lock. Obviously, autofocus lag can be affected by outside factors, such as whether you're shooting a still or moving subject, for example.
- Shutter release lag. This refers to the amount of time it takes from when you fully press the shutter button -- from an already half-pressed shutter button -- to when the shot is recorded. In other words, it's the amount of time to record a shot that has already been pre-focused.
- Total lag. This measures the amount of time it takes from when you fully press the shutter button -- without any half-press pre-focusing -- to when the camera actually records the photograph. It is only really noticeable if using the camera in a quick snapshot, where there is no time to press the shutter halfway to pre-focus the image.
Reducing the effects of shutter lag is something you can do with a little practice ... although it's much more difficult with an inexpensive point and shoot camera than with a nice interchangeable lens camera. Try shooting in good lighting to reduce the effects shutter lag. If you have a moving subject, try shooting it as it moves toward you, rather than shooting as the subject moves across the camera's field of vision. Use the pre-focusing method discussed earlier, by pressing the shutter button halfway. Finally, if you have the option of shooting in manual control and manual focus modes, try it to reduce the effects of shutter lag.