digital photography- Shutter speed..

digital photography- Shutter speed..

What is shutter speed...?????

The camera's shutter speed, the lens's brightness (f-number), and the scene's luminance together determine the amount of light that reaches the film or sensor (the exposure). Exposure value (EV) is a single quantity that accounts for the shutter speed and the f-number.

Multiple combinations of shutter speed and f-number can give the same exposure value. Doubling the exposure time doubles the amount of light (subtracts 1 EV). Making the f-number one stop brighter (reducing the f-number by a factor of ) also doubles the amount of light. A shutter speed of 1/50 s with an f/4.0 lens gives the same exposure value as a 1/100 s shutter with an f/2.8 lens, and also the same exposure value as a 1/200 s shutter with an f/2.0 lens.

In addition to its effect on exposure, the shutter speed changes the way movement appears in photographs. Very short shutter speeds can be used to freeze fast-moving subjects, for example at sporting events. Very long shutter speeds are used to intentionally blur a moving subject for artistic effect.^[2] Short exposure times are sometimes called "fast", and long exposure times "slow".

Adjustment to the aperture controls the depth of field, the distance range over which objects are acceptably sharp; such adjustments need to be compensated by changes in the shutter speed.

In early days of photography, available shutter speeds were not standardized, though a typical sequence might have been 1/10 s, 1/25 s, 1/50 s, 1/100 s, 1/200 s and 1/500 s. Following the adoption of a standardized way of representing 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.), a standardized 2:1 scale was adopted for shutter speed so that opening one aperture stop and reducing the shutter speed by one step resulted in the identical exposure. The agreed standards for shutter speeds are:^[3]

• 1/1000 s
• 1/500 s
• 1/250 s
• 1/125 s
• 1/60 s
• 1/30 s
• 1/15 s
• 1/8 s
• 1/4 s
• 1/2 s
• 1 s

An extended exposure can also allow photographers to catch brief flashes of light, as seen here. Exposure time 15 seconds.

With this scale, each increment roughly doubles the amount of light (longer time) or halves it (shorter time).

Camera shutters often include one or two other settings for making very long exposures:

• B (for bulb) keeps the shutter open as long as the shutter release is held.
• T (for time) keeps the shutter open until the shutter release is pressed again.

The ability of the photographer to take images without noticeable blurring by camera movement is an important parameter in the choice of slowest possible shutter speed for a handheld camera. The rough guide used by most 35 mm photographers is that the slowest shutter speed that can be used easily without much blur due to camera shake is the shutter speed numerically closest to the lens focal length. For example, for handheld use of a 35 mm camera with a 50 mm normal lens, the closest shutter speed is 1/60 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. Through practice and special techniques such as bracing the camera, arms, or body to minimize camera movement longer shutter speeds can be used without blur. If a shutter speed is too slow for hand holding, a camera support, usually a tripod, must be used. Image stabilization can often permit the use of shutter speeds 3–4 stops slower (exposures 8–16 times longer).

Shutter priority refers to a shooting mode used in semi-automatic cameras. It allows the photographer to choose a shutter speed setting and allow the camera to decide the correct aperture. This is sometimes referred to as Shutter Speed Priority Auto Exposure, or TV (time value) mode.