Understanding Exposure and Shutter Speed
Knowing how to manipulate exposure on your camera can create a big impact on your photographs. There are 3 main elements to getting the right exposure for your pictures: the ISO, Aperture and Shutter Speed. Knowing this exposure triangle can spell the difference between a good and bad photograph. ISO refers to your film speed, or the amount of light your film is able to absorb. Though digital photography foregoes film, the ISO is still in place and the principle stays the same. The Aperture refers to the shutter opening, and this controls both amount of light and depth of field.
Shutter Speed settings in your cameras refer to the duration by which your shutter stays open. Usually this is in increments of quarters of a second. The faster your shutter snaps, the less light is registered in your photograph. But this setting does not only control the amount of light; Shutter Speed is also vital for controlling the appearance of moving images.
Fast Shutter Speed
Depending on your lighting condition and your other exposure settings, a fast shutter speed is utilized most during bright daylight. The fastest shutter speed found on a professional DSLR is 1/8000, and this can capture and freeze very fast moving objects - such as a hummingbird in flight. In most consumer DSLRs, you can find 1/4000 to be the fastest shutter speed. This benefits sports photography most, as you can capture any action and movement and freeze it dramatically. The average shutter speed for daylight is 1/500 and 1/250, depending on your other exposure settings. This is good enough to freeze any normal everyday motion without causing a blur.
Slow Shutter Speed
If you want the effect of motion blur, opt for a slower shutter speed. With a good lighting condition, a shutter speed of 1/250 can achieve minimal motion blur. This is usually used when following a moving object, and keeping the subject in focus while the background looks swished. Slower moving objects can still benefit from this effect with a speed of 1/60 or lower. At this speed, photographing moving water will create a dynamic and dramatic effect.
Shutter speeds of 1/15, 1/8, and even lower, are often used for very low lighting conditions. At these speeds, it is advisable to use a tripod. Otherwise, it will almost definitely result in a badly blurred photograph. This speed is also utilized for deliberate motion blur, such as shooting a merry-go-round at night.
The bulb setting in SLRs are for keeping your shutter open for an
indefinite time. This is most useful for nighttime photography, but
under no circumstances should be used without a tripod. Usually Bulb
mode is turned on for exposures requiring longer than 1 second. For
instance, capturing taillight movements in traffic, depending on the
lighting condition, would require a shutter speed of about 30 seconds.
Bulb is also useful for nightscapes or moonlight, when sometimes you
need several minutes' worth of exposure to get the ample effect you
need. Astrophotographers can even keep their shutters open for several
hours in the night.