This is a very simple type of exposure reading where the camera’s light meter just measures the total amount of light in the whole scene. It often leads to underexposure because bright areas in the scene have a disproportionate effect. Today’s digital cameras offer a range of more sophisticated exposure metering patterns and only a few still over averaged metering amongst these – some photographers still like it because although it’s a crude way of measuring the light, it’s quite predictable and easy to interpret.