Once you understand how shutter speed works you need to know how to measure it. The numbers you see on your camera dial/display are different from the actual shutter speed. This lesson will explain what the numbers mean.
Measuring shutter speed is relatively simple. Shutter speed is generally measured in fractions of a second. A shutter speed of "5000" means that the shutter will open for 1/5000th of a second. Shutter speeds of 1 second and longer are generally marked with a ', or other similar mark, after the number. This means that 16' on your camera's display would stand for 16 seconds. The letter "B" is often used to indicate the shutter will remain open as long as you hold down the shutter release button.
Slow Shutter Speed
Shutter speed is considered to be "long" or "slow" when it is slower than 1/60th of a second. (Remember, this is marked as 60 on your camera dial or display.) This numbers comes from the fact that most people can only hold a standard lens (between 35mm and 70mm) steady for 1/60th of a second or less. This is different from the commonly used term "long exposure" which usually refers to shutter speeds of over 1 second.
Fast Shutter Speed
Fast shutter speeds are generally considered to be those shutter speeds faster than 1/500th of a second. These shutter speeds are used to freeze, or stop, motion for a clear image when shooting fast subjects.
Rule of Thumb
A good rule of thumb for knowing the slowest shutter speed you can use with a particular lens, without using a tripod, is to use the number of the lens size. For example, a 300 mm lens can be hand held at shutter speeds of 1/300th of a second and faster. Note that the minimum hand held speed should never be below 1/60th of a second without image stabilization assistance from your camera or lens.