Shutter speed, also referred to as exposure time, is the duration for which the camera's image sensor is exposed to light. The minimum shutter speed is the shortest possible interval for which the camera can keep the shutter open. This value is expressed in fractions of a second, such as 1/4000 s or 1/8000 s. Very short shutter speeds allow for "freezing" even very fast motion, which is useful when photographing sports, flying birds, or moving vehicles. The resulting image is therefore sharp and free of motion blur. Using a short shutter speed means that less light hits the sensor. To achieve a correctly exposed image, it is often necessary to compensate for this light loss, either by setting a lower aperture number, which opens the lens aperture wider, or by increasing the sensor's ISO sensitivity.
