Setting Shutter Speeds

Shutter speed determines how long the shutter remains open

Shutter speed is one of the most basic important controls on a camera. Shutter speed controls the amount of time that your film, or digital sensor, is exposed to light. In effect, the shutter determines what image is captured on your sensor. The shutter is a small plastic membrane that opens and closes to let light onto the sensor or stop light from reaching the sensor. The shutter is opened when you press down on the shutter release button of your camera to take a photo

Wolf moving at a pretty fast pace
Slow shutter speed in combination with panning the camera can achieve a motion blur for moving subjects. The wolf was moving at a pretty fast pace, as you can the focus was on his head.

Other issues that have a bearing upon the overall photograph exposure include; the size of the aperture (the f-number), the time of the exposure (shutter speed) and the scene luminance; photographers can exchange aperture and shutter speed by employing units of stops. One stop either up or down for each unit will cut in half or double the volume of light controlled by each; exposures containing equal exposure values can be readily calculated and chosen. For any particular exposure value or total exposure, a high speed shutter necessitates a bigger aperture (a smaller f-number). In the same way, a slow speed shutter, a longer time length, can be compensated for by selecting a smaller aperture (bigger f-number).

Slower shutter speeds are typically used in poor light situations, prolonging the amount of time before the shutter closes down, which increases the volume of light collected. This fundamental photography principle, the exposure, is employed for both digital and film cameras, as an image sensor effectively acts like film as it's exposed from the shutter.

Shutter speed (Exposure time), is calculate in seconds, although often labeled in reciprocal seconds. The typical photograph exposure time taken in bright sun is 1/125th of a second, most often labeled as 125 on a typical shutter speed dial. Besides to its outcome upon exposure, shutter speed alters the appearance of movement in a photo. Very brief shutter speeds are employed to freeze quick-moving subjects, for instance photographing at at sporting events. Extremely long shutter speeds may be used to purposely blur a subject in motion to obtain an artistic feel.

Waterfall Stabilization Comparisons
Shutter speed can have a dramatic impact impact on moving objects. Changes in background blurring are apparent from the need to adjust the aperture size to achieve correct exposure. as in this image that compares two shots of a waterfall.

Adjusting the aperture has an effect the field depth, the distance reach over which objects appear acceptably sharp; although any adjustments usually need to be offset by also changing the shutter speed.

Early on in the days of photography, offered shutter speeds were to some extent makeshift. Later a uniform way of denoting aperture sizes was adopted so that each main step precisely halved or doubled the light volume flowing into the camera (i.e, f/2.8, f/4, f/5.6, f/8, f/11, f/16), a uniform 2:1 scale was embraced for shutter speeds so that decreasing a shutter speed by one step and increasing one aperture stop resulted in identical exposures. The adopted shutter speeds standards are:

    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,

Each standard increment either doubles the amount of light (longer time) or halves the amount of light (shorter time). For example, if you move from 1 sec to 1/2 second, you have effectively halved the amount of light entering the shutter. This scale can be extended at either end in specialist cameras. Some older cameras use the 2:1 ratio at slightly different values, such as 1/100 s and 1/50 s, although mechanical shutter mechanisms were rarely precise enough for the difference to have any significance.

Shutter Speed Chart
Shutter Speed Chart

The term "speed" is used in reference to short exposure times as fast, and long exposure times as slow. Shutter speeds are often designated by the reciprocal time, for example 60 for 1/60 s.

Camera shutters typically include one or two additional settings for acquiring extremely long exposures:

  • B (for bulb) keep the shutter open for as long as the shutter release is set
  • T (for time) keep the shutter open until the shutter release is pressed a second time

The capacity of a photographer to shoot photos without noticeable camera movement blur is an important consideration in choosing the slowest available shutter speed for handholding a camera. The general rule used by most 35mm photographers is the slowest shutter setting which can be easily used without a lot of blur because of camera shake becomes the numerical shutter speed closest to the focal length of the lens. For instance, for handholding a 35mm camera while using a 50mm standard lens, the nearest shutter speed is 1/60 s. The guideline can be tweaked with awareness of the proposed application of the image, a photo proposed for considerable enlarging and close up presentation would need a faster shutter speed to avoid apparent blur. Through much practice and learned techniques like bracing the arms, camera, or body to lessen camera movements longer shutter speeds may be employed without noticeable blur. When using a shutter speed that's too slow hold by hand, a camera support, typically a tripod, should be used. Also, Image stabilization can many times allow using of shutter speeds as much as 3-4 stops less (exposures that are 8-16 times longer). updated article Sep 16, 2011

Setting Shutter priority

Shutter priority is in reference to a shooting method that may be used with a semi-automatic camera. It permits the photographer to select a setting for shutter speed and let the camera to choose the proper aperture. Sometimes this is called Tv (time value) or Shutter Speed Priority Auto Exposure.

This is different than manual mode, where a photographer must select both values, or aperture priority where a photographer chooses an aperture where the camera picks a matching shutter speed, or program mode whereas both are chosen by the camera.

Shutter priority using longer exposures is selected to create a feeling of motion. For instance, a waterfall will turn out fuzzy and blurred . Panning the camera with a subject that's moving such as the wolf above, the background will seem blurred. When shooting sports or fast action, shutter priority using a short exposure can assure that the motion becomes virtually frozen for the image that results. Typically, shutter priority is abbreviated as Tv (literally for, "time value") or just S on a camera mode dial.

Creative Efficacy in Photography

Shutter speed is just one of various methods employed for controlling the volume of light captured by the camera's image sensor or film. It is also employed to control the visual results of the final picture beyond its radiance. A slower shutter speed is typically chosen to imply movement within a still image of an object that's moving. Overly fast shutter speeds may cause a subject that's moving to have an unnatural frozen appearance. For example, a person running may be captured with both their feet off the ground and any indication of movement will lost within the frozen instant.

When a lesser shutter speed is chosen, a longer period of time goes by from the instant the shutter is opened until the moment it is closed. and consequently more time is on hand for subject movement to be captured by the camera. Using a somewhat slower speed for the shutter will let the photographer introduce a touch of blur, either for the moving subject, as in the above example, their feet, which were the fastest moving things within the frame, might become blurred while the balance remains sharp; or by panning the camera to follow a subject that's moving, the background becomes blurred letting the subject stay sharp.

The precise spot at which the subject or background will become blurred depends upon the subject's distance with relation to the camera, the speed the object is traveling, and the lens focal length with relation to the image sensor or film speed.

Using slower shutter speeds, exceeding a half a second or more, for running water, the resulting image will feature a ghostly white look reminiscent of fog. This technique can be used with landscape photography.

Zoom burst is another technique which involves a variation of a zoom lens's focal length during a lengthier exposure time. In the instant that a shutter is opened, zooming the lens in, thereby altering the focal length while the shutter is open. The image center remains sharp and in-focus, letting the details nearer the edges form a radial blur, causing a strong visual result, compelling the eye to move into the middle of the image.

updated article Sep 16, 2011

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