Learning how to use your camera's shutter speeds correctly helps to create dramatic and correctly exposed images. The shutter speed controls the length of time the shutter of the camera is open, and, therefore, how much light is allowed to strike the image sensor.
Shutter speed is primarily used for freezing action or for long nighttime exposures. A good way to start experimenting with shutter speeds is to put the camera into "shutter priority mode." This is represented by either an "S" or the letters "TV" on the mode dial on the top of your DSLR camera. Some advanced point and shoot cameras also offer a shutter priority mode.
Continue reading to answer the question: What is shutter priority mode?
When Would a Photographer Use Shutter Priority Mode?
As mentioned, the primary reasons for using this mode are to freeze action or for long exposures. In other words, shutter priority mode is used when a photographer needs to use the extremes of the shutter speed range.
If a photographer is shooting fast moving objects -- such as cars (as shown above), people playing sports, or wildlife -- a fast shutter speed of between 1/800th of a second and 1/8000th of a second will be needed. The exact shutter speed used usually depends on available light, as, at 1/8000th, very little light will enter the camera and strike the image sensor.
The shutter speed you will want to use will also depend on how much motion blur the photographer wants to keep in the image. For instance, at 1/8000th, everything will be frozen, including the background, and this can make things such as cars look a little static. So photographers sometimes drop the shutter speed a little so that action is still frozen, but some movement in the background occurs.
Photographers also use shutter priority mode when shooting at night or when photographing water. In this case, a slow shutter speed is needed -- anything from a few seconds right down to the "Bulb" setting, which allows the photographer to keep the shutter open for as long as he or she chooses. A long shutter speed is needed at night if the photographer doesn't want to use any artificial lighting. This allows for natural shots of the stars, or shots of buildings that are lit up at night. Photographers also often use a long shutter speed when shooting waterfalls, as keeping the shutter open for a longer time turns the water into an ethereal mist, which can be far more flattering in an image.
What to Watch For When Shooting in Shutter Priority Mode
First, remember that if you shoot at any speed below 1/60th, you're likely to encounter camera shake, which may cause blur in your images. For long exposures, you need to use a tripod, a pod, or -- as a last resort -- a secure wall on which to rest your camera. When shooting with a slow shutter speed, don't forget to use the self timer to take the shot, otherwise you could slightly jar the camera when you press the shutter, which again may cause camera shake.
Second, you need to remember your aperture setting! If you're shooting at a very fast shutter speed when the light isn't particularly bright, your camera will chose a large aperture to compensate. This will then leave you with a very narrow depth of field. Obviously, that's fine if it suits the style of your photo but, if not, you'll need to possibly lower your shutter speed slightly and, if all else fails, push your ISO up to get more light into the camera's image sensor.