Shutter Speed is measured in fractions of a second, and refers to the length of time the camera shutter is open to allow light to make contact with the camera sensor (or camera film). The traditional way cameras indicate this setting is with fraction notation, though some camera now use the denominator (bottom) number of the fraction. In this format, a shutter speed of 60 equals 1/60th of a second, not 60 seconds. Most cameras allow exposures longer than a full second. In that case, the number is noted with a ” after. For example, 30″ would be a 30 second exposure.
SHUTTER SPEED AND AVAILABLE LIGHT
The longer the shutter is open, the more time the camera is allowing visible light to make contact with the sensor. When there is not much available light (e.g. indoors, late evening) the shutter needs to stay open longer for the image to be bright enough to be properly exposed. On bright light days, the shutter needs to open and close extremely fast to avoid photographs from being over-exposure.
THE CAMERA CONNECTION When shooting action photos, the “Sports Mode” on most camera places priority on Shutter Speed. The camera will try to take the fastest possible shutter speed with the amount of light available. When in “Sports Mode” however, some cameras won’t take the image if the camera can’t select a fast enough shutter speed. You can take control of the camera by selecting the Shutter Priority shooting mode. This is usually indicated with the symbol (Tv), or (S) on the Shooting Mode dial. When shooting in Shutter Priority, YOU select the shutter speed, and the camera balances the exposure by choosing the aperture. Depending on the setting, you may need to adjust ISO to gain balance available light for a good exposure.
USES AND TRADE-OFFS
The primary use for shutter speed is to stop motion. The potential trade-offs for selecting a slow shutter speed are possibly introducing image blur. On the other end, selecting a shutter speed that is fast enough to stop fast motion requires the camera to capture more light; either through setting the ISO to a higher sensitivity rating (e.g. ISO 800) or by selecting a wide aperture (e.g. f/3.5)
Since action photography often requires the action to be frozen in time, Shutter Speed is most often the highest priority. The drawback most often arises during low light situations. Fast shutter speeds require more light. If more light is attained through a larger aperture (f/2.8) the loser is the depth of focus your image has. (e.g. a swimmer doing the butterfly might have a sharp focus on the face, but out of focus arms).
THRESHOLDS
You may think this is unnecessary for doing portraits, or still photography, but even in these situations the photographer has to be able to hold the camera still – which can sometimes be challenging. The following thresholds may serve as a guide for gauging an appropriate shutter speed.
- less than (<) 1/60 second – a tripod is necessary for most people even when shooting still life, or portraits.
- 1/60 – 1/125: portraits, or still photography without a tripod
- 1/125 – 1/250: slow action such as long distance running, walking, slow biking, pets moving, gentle flowing streams, flags in light wind, reactions such as laughter.
- 1/250 – 1/500: faster action such as sprinting, small birds flying, spinning objects, sledding downhill, rushing water.
- 1/500 – 1/1000: baseball pitches or hits, hockey shots, waterfalls
- greater than (>) 1/1000: race vehicles, hummingbird wings, soap bubble popping
FINER POINTS: FACTOR IN THE LENS LENGTH
Camera lens length can also be a factor is stability since both the weight of the lens, and the amount of magnification of the image can introduce lens shake into the image. A good rule of thumb is to make sure you are shooting at a shutter speed where the fraction of a second is as fast, or faster that the length of the lens, PLUS compensates for the type of motion going on.
For example, if photographing a baseball game with a 200mm lens, the photographer would select a minimum of 1/200 shutter speed to compensate for the lens. To capture players standing around, 1/200 would be fine, but to capture a runner the photographer would choose 1/200 for the lens, plus an additional 1/125 for the speed of the runner to assure stop action. Greater than 1/400 would be a good shutter speed to start. If the photographer wanted to try to capture a swing of the batter, selecting 1/1000 second or greater would be a recommended starting point to account for the lens magnification, and action.
The following video illustrates a series of photos taken in Shutter Speed Priority, and how the camera adjusts the aperture to create the correct exposure.
[youtube https://www.youtube.com/watch?v=vMiVTbGtIiE&w=420&h=315]