Last year, I stumbled upon a mob of kangaroo while hiking through the bush. The lighting conditions were tricky, but I was in a hurry to snap some pictures of this unusual (for me) discovery. As I suspected, the large--but shy--animals didn't stick around very long, so I only got a few photos before they disappeared into the brush. When I got home, I was disappointed to find that none of the pictures were very good. They were all underexposed, thanks to the strong backlight in the direction I had to shoot. Rats! If only I had bracketed my exposures.
Bracketing is an old pro-photographer trick from the days of film photography. In a nutshell, bracketing is the practice of taking several photos instead of just one, but varying the exposure a little in each shot. Most of the photos will probably be throwaways, but if you aren't sure what the right exposure is, one of the shots should be just right.
If bracketing sounds like a good idea to you, then you'll be happy to know that your digital camera might already have a bracketing feature built right in. Many modern digital cameras--especially digital SLRs--make it easy to bracket your exposures. Even some point-and-shoot models have a bracketing feature.
Generally, you have to make two decisions when you start bracketing your pictures: You can control how many pictures are taken in a bracketing series, as well as how much the exposure changes from one picture to the next.
The most common bracketing mode uses three exposures. When you configure your camera for a three-exposure bracket, the camera will take, not surprisingly, three pictures. The first picture will be properly exposed according to whatever the camera's exposure meter thinks is correct for this scene. That picture is exactly the same as what you would get if you simply took a picture on automatic exposure. The next picture will be somewhat underexposed, and the final picture will be somewhat overexposed. When you download these pictures to on your computer, you can see which one was best, and discard the two you don't need. It's a great insurance policy.
Your camera's bracketing may vary. Many point-and-shoot models offer the three-exposure bracket only, while some cameras let you dial in five or even seven photos. Some cameras don't let you configure how much you over- or underexposure each image. Other cameras let you choose as little as one-third of a stop to as much as a full stop between each image.
After you turn on the bracketing mode, using it is easy. Frame your photo, and then press and hold the shutter release as the camera takes all the pictures in the bracketing series, one after the other, and then stops automatically when it's done.
Bracketing on Your Own
Suppose you don't have a bracketing feature built into your digital camera. Are you out of luck? Of course not. You can simulate bracketing with any digital camera, though it won't be quite as automatic.
Suppose you want to take a three-exposure series--the first picture at the camera's recommended exposure, the second underexposed, and the third overexposed. Simply take the first picture the way you ordinarily would. Then change the exposure compensation setting on your camera to underexpose the picture by one stop. Recompose the picture and take it again. Finally, switch the exposure compensation to overexpose by one stop, line it up, and shoot. Don't forget to change the exposure compensation back to zero so the next picture will be properly exposed.
You may not be completely in the dark about what the right exposure should be. For instance, you might realize that your environment is likely to produce an underexposed picture. Using bracketing to create an overexposed image just wastes storage space. So why bother? If you're confident enough to try it, check your camera for a bracketing mode that adds only underexposed (or overexposed, as the case may be) images to your camera's chosen exposure. If you're bracketing manually, take a series of photos with increasingly higher levels of over- or underexposure, but don't bother adjusting in the other direction.
What's it all look like? Here is a three-photo series I took with my camera's bracketing control set on one stop.