Most cameras have three options for how the exposure or light meter works: spot metering, center weighted metering and matrix or evaluative metering.
Matrix metering
It is the standard setting on most DSRL and mirrorless cameras. In this mode, the camera reads the exposure from all areas of the frame. Based off the lighting of your frame, it will tell you a balanced exposure for the entire scene. It might be the best option when running around with your camera in different lighting situation.
Spot metering
The camera only evaluates the light around a single focus point. Typically, this will be the center point of the frame, but it can also be moved around to any other part of the frame with many different cameras. The camera will read the exposure of that specific point and tell if it is exposed or not. Using the spot metering mode is good when photographing smaller subjects in a larger frame that has a contrasting exposure, such as a bright moon in a dark sky or a dark animal in the middle of a snowy field. The spot metering mode also changes depending on where you are focusing, if you are focusing on something very close or very far, it will change the exposure reading.
Center-weighted metering
It reads the exposure of the center point of the frame and the surrounding, ignoring the corners of the frame. It doesn’t take in account where you are focusing but just what is in the center of the frame. It is great when your subjects will be in the center, like portraits.
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