Digital Photography Tips and Tutorials · Exposure Bracketing

What this is about:

The correct exposure is perhaps the most fundamentally important aspect of taking a good photograph. It doesn`t matter how well a picture is composed or how well it tells the story, if a photo is under or over-exposed its value is lost. So learning to manage the exposure compensation options on your digital camera shouldn't be bypassed. The fact is it's very easy to do with exposure bracketing.

Improving Your Exposures with Bracketing

Photo bracketing instructs the camera to take more than one picture of the same scene, each with different exposures, to ensure you cover the possibility of under or over-exposure. Doing this manually would involve taking one picture, then making adjustments to either shutter speed or aperture and taking another picture... and again making more changes before taking a third. Digital cameras make this procedure much easier.

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When you expose for a scene, your camera's light meter will select an aperture / shutter speed combination that it believes will produce a properly exposed photo. Most contemporary digital cameras have an automatic bracketing feature that can be selected as often or as little as required. When selected, the camera will take multiple images with incremental changes in exposure. In the camera owner's manual this is generally referred to as AEB. This option can sometimes be turned on with a button on the camera and other times it is found within the menu settings.

With most digital cameras it is possible to choose the degree of compensation used, so you could have the bracketed photos exposed by an extra half stop, full stop, or even two stops. This simply means the degree negative or positive compensation used by the camera for each additional picture. It is usual to take two extra photos, but some cameras have the option for taking five pictures in all, two "lighter" and two "darker" than the settings the light meter selected for the first image. The amount of under and over-exposure usually defaults to -1/3EV and +1/3EV, but can also be specified in the preferences setup.

When Should You Use Exposure Bracketing?

Difficulties in getting the right exposure generally occur when lighting conditions are tricky. For example, when there is a lot of contrast between the dark areas of a scene and the light areas. The camera's light meter can be tricked into misreading the lighting in a scene — back lighting and snow scenes are two common scenarios when photographers can be disappointed with their results. In both cases the meter misreads the amount of available light and the shutter speed is too fast, failing to allow enough light in. It is worth using bracketing whenever the photo you are taking really matters.

Anytime you feel your photographic subject has a challenging lighting situation — for example, sunrises and sunsets are usually better photographed slightly under-exposed, or a canopied forest would turn out better with over-exposure compensation — that is the proper time to use bracketing. After all, you aren't using film anymore, so the additional images saved to create the bracket don't cost a thing.

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Should you delete the extra photos right away? No, if you aren't storage constrained, keep all three (or five) shots until you get them uploaded to your computer. Once gone from the camera, data recovery is impossible, and it would be a shame to use bracketing and still miss out on the best image. Using the layering features of photo editing software, you can load the entire bracket into different layers and then carefully erase the under or over-exposed sections of one or more of the layers to end up with a final image where the focal point and the surroundings are properly exposed.

Another option to consider with bracketed photos is HDR; high-dynamic-range imaging. HDR is a set of techniques that allow a greater dynamic range of luminance between the lightest and darkest areas of an image than current standard digital imaging techniques or photographic methods. This wide dynamic range allows HDR images to more accurately represent the range of intensity levels found in real scenes, ranging from direct sunlight to faint starlight. Merging multiple photographs is one common methodology for applying HDR to your images.