Bracketing Exposures Automatically on Canon Rebel T3 Series Cameras
Many photographers use a strategy called bracketing to ensure that at least one shot of a subject is properly exposed. They shoot the same subject multiple times, slightly varying the exposure settings for each image. To make bracketing easy, your Canon Rebel T3 or T3i offers automatic exposure bracketing (AEB). When you enable this feature, your only job is to press the shutter button to record the shots; the camera automatically adjusts the exposure settings between each image.
Aside from cover-your, uh, "bases" shooting, bracketing is useful for HDR imaging. HDR stands for high dynamic range, with dynamic range referring to the spectrum of brightness values in a photograph. The idea behind HDR is to capture the same shot multiple times, using different exposure settings for each image. You then use special imaging software, called tone mapping software, to combine the exposures in a way that uses specific brightness values from each shot. By using this process, you get a shot that contains more detail in both the highlights and shadows than a camera could ever record in a single image.
When applied to its extreme limits, HDR produces images that have something of a graphic-novel look.
Whether you're interested in automatic exposure bracketing for HDR or just want to give yourself an exposure safety net, keep these points in mind:
Exposure mode: AEB is available only in the P, Tv, Av, M, and A-DEP exposure modes.
Flash: AEB isn’t available when you use flash. You can still bracket your shots — you just have to change the exposure settings between frames yourself.
Bracketing amount: You can request an exposure change of up to two stops from the auto bracketing system.
Exposure Compensation: You can combine AEB with Exposure Compensation if you want. The camera simply applies the compensation amount when it calculates the exposure for the three bracketed images.
Auto Lighting Optimizer: Because that feature is designed to automatically adjust images that are underexposed or lacking in contrast, it can render AEB ineffective. So it’s best to disable the feature when bracketing.