Shutter speed

The camera's shutter speed, the lens's aperture or f-stop, and the scene's luminance together determine the amount of light that reaches the film or sensor (the exposure).

Reducing the aperture size at multiples of one over the square root of two lets half as much light into the camera, usually at a predefined scale of f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, and so on.

[citation needed] In addition to its effect on exposure, the shutter speed changes the way movement appears in photographs.

Soon this problem resulted in a solution consisting in the adoption of a standardized way of choosing aperture so that each major step exactly doubled or halved the amount of light entering the camera (f/2.8, f/4, f/5.6, f/8, f/11, f/16, etc.

For example, for handheld use of a 35 mm camera with a 50 mm normal lens, the closest shutter speed is 1⁄60 s (closest to "50"), while for a 200 mm lens it is recommended not to choose shutter speeds below 1⁄200 s. This rule can be augmented with knowledge of the intended application for the photograph, an image intended for significant enlargement and closeup viewing would require faster shutter speeds to avoid obvious blur.

Image stabilization on digital cameras or lenses can often permit the use of shutter speeds 3–4 stops slower (exposures 8–16 times longer).

[citation needed] Shutter speed is one of several methods used to control the amount of light recorded by the camera's digital sensor or film.

For instance, a running person may be caught with both feet in the air with all indication of movement lost in the frozen moment.

The exact point at which the background or subject will start to blur depends on the speed at which the object is moving, the angle that the object is moving in relation to the camera, the distance it is from the camera and the focal length of the lens in relation to the size of the digital sensor or film.

Motion picture cameras used in traditional film cinematography employ a mechanical rotating shutter.

A spoon falling in water, taken at 1 ⁄ 2000 s
Shutter speed can have a dramatic impact on the appearance and quality of photographs, especially when moving objects are involved. For instance a slow shutter-speed often results in a blurred image as the slight shudder of the shutter itself, or the motion caused to the whole camera by the index pressing on the shutter-release button create vibrations that are faster than the shutter itself; this will cause the appearance of the objects in the view-finder and on the photographs having moved when in fact it is the camera that moved.
The shutter speed dial of a Nikkormat EL
Slow shutter speed combined with panning the camera can achieve a motion blur for moving objects.
Different shutter speeds for a CPU fan. Shutter speeds from first to last: 2 s, 1 s, 1 ⁄ 10 s, 1 ⁄ 100 s, 1 ⁄ 200 s, 1 ⁄ 500 s, 1 ⁄ 1000 s, 1 ⁄ 2000 s, 1 ⁄ 4000 s
An extended exposure can also allow photographers to catch brief flashes of light, as seen here. Exposure time 15 seconds.
Sparklers moved in a circular motion with an exposure time of 4 seconds. This is an example of light painting .
Images taken with a lower shutter speed evoke a visual sense of movement. Exposure time 3 seconds.