Average metering takes all of the light values for a given scene—highlights, shadows, and mid-tones—and averages them together to establish an overall exposure. Average metering is best used for front-lit subjects under average lighting conditions. Backlit subjects tend to be silhouetted when metered in average mode. For more on this subject, see the explora article, ://www.bhphotovideo.com/explora/photography/tips-and-solutions/understanding-camera-metering-modes Understanding Camera Metering Modes.bhphotovideo
Evaluative through the lens flash metering pattern that weights all metering segments equally.
A measure of contrast of a photographic image, representing the slope of a portion of a characteristic curve. The term that refers to a numerical means for indicating the contrast or the photographic image.