Bracketing is taking several shots of the same subject using different exposure settings. Usually, three shots are taken.
- The exposure the camera thinks is correct
- One shot lighter
- One shot darker
Any of the settings that affect exposure (aperture, speed, ISO) can be used to manually bracket shots.
The main reason I bracket is to produce three shots that can be merged together as an HDR image. When bracketing to create an HDR image, don’t change the aperture. Just change the shutter speed. If you change the aperture, you will also change the depth of field in each of the bracketed shots. Changing ISO could introduce digital noise. Since HDR images are already noisy, reducing digital noise is the better choice. Another reason to bracket has to do with lighting conditions. If your camera is having problems finding the best exposure, you can turn on bracketing so that you have a range of exposures for every shot.
Automatic Exposure Bracketing (AEB)
Automatic Exposure Bracketing is a special setting in your camera that causes the camera to take three different shots. You determine the number of stops that will be in between each shot. AEB changes just the shutter speed to create the different exposures. You may have to dig into the menus of your camera to be able to turn on Automatic Exposure Bracketing. The location may change from model to model within the same product line. One of the features I like the most about my Canon 60D is that it remembers that I have turned on AEB even when the camera is turned off and back on. My Canon T1i didn’t do that. Every time that my T1i went to sleep or I turned it off, I had to go back into the menus to turn AEB back on.
Continuous Shooting (Burst) Mode
Continuous shooting mode and bracketing go hand in hand. By turning on continuous shooting mode, you only have to hold down the shutter button in order to take all three bracketed shots. Without continuous shooting mode turned on, you would have to press the shutter button for each shot. By turning on AEB and continuous shooting mode, I can take three shots in a row with one press of the shutter release. Sometimes, three shots aren’t enough to capture the full range of light in the scene. For instance, it is possible for the sky to be nine times brighter than the land. There are times when I have taken nine exposures. If you want help deciding what speed to use when taking more than three bracketed shots, use an iPhone/iPad app such as PhotoBuddy. This clever app can calculate the speed settings required to take many exposures without overlapping exposures.