Photography basics – Shutter Speed

The shutter speed is the duration during which the shutter of the camera stays open to let light shine on the sensor or film.
 

Think of the shutter as a very fast opening and closing curtain.
 
The longer the curtain stays open, the longer the sensor or film is exposed to the light.
 
This allows the photographer to use the shutter speed to control the exposure. All other things remaining the same; if you double the shutter speed, you double the amount of light that hits the sensor.
 
The required shutter speed for correct exposure depends on the ISO and the aperture.
 
The shutter speed is also important for photographing things in motion. A ‘fast’ or short shutter speed is needed to capture moving things without blur. For example, a speed of 1/60 or 1/125 is often enough to freeze a moving person. On the other hand, a faster speed of 1/500 or 1/1000 will be needed to freeze the motion of a car.
 
A ’slow’ or long shutter speed is needed when there is not much light. The drawback to this is twofold:
1. You cannot freeze moving objects anymore: Since the shutter speed is long, they will move during the exposure and therefore will be blurred.
2. Your shot will be affected by camera shake. If the shutter is speed is slow enough, the camera shake caused by your hand will be visible in the shot.
 
To prevent camera shake, the usual rule of thumb is that your shutter speed should be 1 / focal length that you are using.
 
Since shutter speed is usually expressed as 1 / x seconds, it is easy to work out what sort of shutter speed you need to prevent camera shake.
 
We always think of a picture as a frozen instant of time. Of course this is never completely true, the picture is usually taken in a small but measurable time. The shutter speed allows you to choose how long this time should be.