DSLR Camera Basics
Exposure compensation is used to alter exposure from the value selected by the camera, making photographs brighter or darker.
In modes P, S, and A, the camera automatically adjusts settings for optimal exposure, but this may not always produce the exposure the photographer intended. Exposure is a matter of personal preference, and an exposure brighter or darker than that selected by the camera may sometimes better reflect the photographer's intent. The feature used in such situations is called exposure compensation. DSLR Cameras allow you to check the results immediately, so you can take a photograph, display it in the monitor, and then raise exposure compensation for brighter results or lower exposure compensation for darker results and take another picture.
Sample Camera Displays
Displayed as …–1.0, –0.7, –0.3, 0.0, +0.3, +0.7, +1.0…, where “–1.0” is one step darker than the optimal exposure value selected by the camera.