Exposure compensation

Factors considered may include unusual lighting distribution, variations within a camera system, filters, non-standard processing, or intended underexposure or overexposure.

Many modern cameras incorporate metering systems that measure scene contrast as well as average luminance, and employ sophisticated algorithms to infer the appropriate exposure from these data.

In scenes with very unusual lighting, however, these metering systems sometimes cannot match the judgment of a skilled photographer, so exposure compensation still may be needed.

[2] An early application of exposure compensation was the Zone System developed by Ansel Adams and Fred Archer.

The Zone System is a very specialized form of exposure compensation, and is used most effectively when metering individual scene elements, such as a sunlit rock or the bark of a tree in shade.

Many cameras incorporate narrow-angle spot meters to facilitate such measurements.