A fast shutter speed means that the shutter is only open for a short period of time; a slow shutter speed means the shutter is open for longer.
HOW IS SHUTTER SPEED MEASURED?
Shutter speeds are measured in seconds, or fractions of a second. For example, a shutter speed of 1/100 means 1/100th of a second, or 0.01 seconds. This is also known as the “exposure time”, because it’s the amount of time the sensor is exposed to light.
Most cameras offer a wide range of shutter speeds, starting at just a few thousandths of a second and going up to several seconds. SLRs also have a “Bulb” mode where you can hold the shutter open for as long as you want.
CHOOSING THE BEST SHUTTER SPEED
In automatic mode, your camera will try to guess the best shutter speed to capture your scene. Unfortunately it doesn’t always get it right, and your photo can end up poorly exposed or blurred.
A better option is to switch to manual mode and take control of shutter speed yourself. When doing so, you need to consider the following: