One of the best ways to improve your underwater photography skills is to learn about shutter speed. Understanding how this essential tool for taking underwater photos works will make a major difference in the way your photos turn out. It's not rocket science; in fact, shutter speed is very simple to understand. Grab your camera, and let's go over what shutter speed is, and learn how to use it to create great images.
What is Shutter Speed?
Shutter speed is a measurement of the opening and closing of the shutter, which determines how much light enters the camera. Shooting at "one over 15" or "1/15th" means that the shutter stays open for one fifteenth of a second.
When you change the shutter speed, the amount of light allowed into the camera changes. The slower the shutter speed, the more light is allowed in. In low light situations, slow shutter speeds are often preferable to faster ones, and vice-versa.
Very high shutter speeds freeze motion; capturing a fast moving sea lion, dolphin, or other animal calls for speeds of 1/200th or faster for crisp photos. Fast shutter speeds also help to capture sunbursts.
Medium shutter speeds between 1/30th and 1/100th are usually not adequate for capturing most moving objects, although they are ideal for getting nice color on still subjects. If you're interested in creative effects like motion trails, then go for slow shutter speeds from 1 second to 1/15th, and do not move the camera at all or the entire photo will blur. Using a slow shutter speed can also help achieve a beautiful blue background.
Freezing Motion and Getting Sharp Photos
Unless you're trying to get a blue background, shutter speed can be almost irrelevant when using strobes. If you're working mostly with ambient light, follow these basic guidelines to get crisp photos and freeze motion.
When the subject is still, you can us 1/20th to 1/125th, depending on the lens's focal length. If you're not the best at holding your camera steady or if you're working in current, go with a higher number.
When your subject is moving slowly, you'll get the best results with 1/50th to 1/125th, and when subjects are moving quickly, you'll need 1/125th or higher. The faster moving your subject is, the faster your shutter speed needs to be.
Synchronizing With Strobes
Your camera's shutter has a maximum shutter speed that will work with either an internal or external flash or strobe. This speed is known as sync speed, and varies from one camera to the next. if you try to use your strobes and have the shutter speed set faster than the maximum, your photos will come out mostly black because the shutter is raising or lowering as the strobe fires. Test your camera and strobes topside to see just how fast you can go to prevent this from happening underwater while you're trying to capture that once in a lifetime shot.
As you can see, shutter speed is an excellent tool you can use to get the best underwater photos possible. The more you practice, the more automatic your responses will be, and the better all your photos, topside and underwater both, will turn out.