Light passes through the camera’s lens, but is only allowed to reach the film or sensor when a mechanical curtain, called the shutter, is opened by pressing the shutter button. Â The length of time that the shutter is open is called the shutter speed, and it is expressed as a fraction of a second.
A fast shutter speed, like 1/2000 of a second, will stop motion in an image. Â A long shutter speed of several seconds could be used to reveal the motion of a flowing river, or other dynamic subjects. Â Shutter speed is one of the three pillars of exposure, along with ISO and aperture. Â It gives us incredible creative control and the ability to convey motion, even in a single image. Â In automatic exposure modes the camera will select a shutter speed for you, in shutter speed priority mode (TV), the photographer selects the best shutter speed for the subject, and the camera calculates the correct aperture for a properly exposed image.
