All About Shutter Speeds

Background
The shutter speed is the amount of time that the film or CCD sensor is exposed to light, also known as the exposure or exposure time.

Theory
Shutter speeds are normally quoted in fractions of a second, written as eg. 1/30, which would mean one thirtieth of a second. Like apertures and ISO speeds, they normally follow a standard pattern:

1/1000th, 1/500th, 1/250th, 1/125th, 1/60th, 1/30th, 1/15th etc.

This list runs from shortest/fastest (1/1000th of a second) to longest (1/15th). Some cameras will take shorter exposures (perhaps up to 1/8000th of a second). Longer shutter speeds are often written with the following notation:

0"5, 1", 1.5", 2" ... bulb

This means half a second, one second, etc. BULB is a special case, usually only available withe some SLR cameras, which basically means the shutter is held open for as long as you hold your finger on the button (known as Bulb from an old sort of cable release, with an air tube and bulb at the end, which was used to fire the shutter). Not all cameras will display the shutter speed they are using in the viewfinder, but most SLRs should. They usually just show the portion under the dividing line, so 1/500th would be displayed as 500 in the viewfinder.

Examples
What does this mean for your pictures? Here are some advantages and disadvantages of two extremes of the shutter range:

1/1000th

• Best in sunny conditions outdoors
• Good at freezing movement in water or moving objects such as racing cars
• Unlikely to result in blurred pictures due to camera shake
• Usually requires the use of the lens's largest aperture setting, eg f/4

[1/400th at f/8 with ISO200 - the water droplets are distinct and the main flow from the gargoyle's mouth breaks up at the end. An even higher shutter speed (1/1000th) would have frozen the droplets even better]

1/15th

• Better in dull conditions - overcast days or indoors without flash
• Good at portraying movement lines, such as flowing water, fireworks
• Prone to unwanted blurry pictures if not using a tripod or Image Stabilised lens
• Can be used with higher aperture settings in bright conditions, eg f/16

[1/30th at f/32 with ISO200 - the water droplets blur into lines showing their flow. An even longer shutter speed (1/10th) would have made the movement lines even more obvious]

Usually, camera shake (unintentional movement blur) due to long exposure times is unwanted. But you can use a slow shutter speed and deliberately move the camera to make some abstract patterns:

[Thames Impression IV - 1 second at f/5.6 and ISO800. The camera was deliberately moved during the exposure time]

As good practice, why not turn your camera to TV (shutter-priority) mode and take a few pictures of the same subject, but using different shutter speeds. This will show you exactly what the effects of controlling the exposure time can do for your photographs.