Adjusting Shutter Speed

The shutter controls the length of time that light is allowed to enter the camera, and is usually expressed in a standard series of fractions of a second, such as:

1/8 1/15 1/30 1/60 1/125 1/500 1/1000

Conventionally cameras used this set list of speeds. Some modern electronically controlled shutters using LCD panels for setting, allow speeds between these. It is one of those "added features" that make operating a camera slower and less intuitive, and is seldom if ever of use.

Correct exposure depends on the light level and film speed (or sensor sensitivity.) As mentioned above, there is always a choice of suitable combinations of shutter speed and aperture, all of which give the same amount of light. See example below.

1/500 f4 1/250 f5.6 1/125 f11 1/60 f16

Shutter Speed and Subject Movement

The shutter controls the length of time that light is allowed to enter the camera, and is usually expressed in a standard series of fractions of a second.

Conventionally cameras used this set list of speeds. Some modern electronically controlled shutters using LCD panels for setting, allow speeds between these. It is one of those "added features" that make operating a camera slower and less intuitive, and is seldom if ever of use.

Correct exposure depends on the light level and film speed (or sensor sensitivity.) As mentioned above, there is always a choice of suitable combinations of shutter speed and aperture.

Shutter Speed and Focal Length

Shutter speed is also important in cutting down camera shake. For 35mm cameras a good rule of thumb is always to use a shutter speed that is equal to or faster than 1/focal length. So with a standard focal length lens of 50 mm, you should use shutter speeds of 1/50 or faster, while a 500 mm lens needs 1/500.

When working with a digital camera, you should use the '35mm equivalent' focal lengths for similar calculations. As you zoom out towards greater magnification you need to remember you are also zooming your camera shake. If you can set a faster shutter speed you should consider doing so.

The faster speeds are needed because the longer the focal length the more any slight movements are magnified in the image. Some recent lenses incorporate image stabilisation using motion sensors; in some digital cameras the same function is performed digitally. Image stabilisation enables you to use significantly slower shutter speeds without getting camera shake, but does not of course reduce any problems caused by subject movement.

In the traditional SLR camera design, one cause of camera shake was the mirror which had to flip up immediately before exposure to allow the light to reach the film. Cameras without this - including most digitals except some of the interchangeable lens SLR digitals - have an advantage in avoiding shake. Many photographers have used rangefinder cameras such as the Leica series handheld with standard 50mm lenses with success at 1/15 or even 1/8 second.

Here are a couple of links that might help to explain it better: Shutter Speed Help and Shutter Bug.