Chapter 01: Camera and sensor types
Metering is the process your camera uses to measure the brightness of a scene so it can determine the correct exposure settings, typically shutter speed, aperture, and ISO. There are different modes of metering; matrix metering might expose for the whole scene. If there are very light areas in the frame this may make the darker areas very dark. Note that this can be fixed in image editing later on. In centre‑weighted metering the camera measures the whole frame but gives extra importance to the centre. Spot metering measures a very small area of the frame (often 1–5%) of your choice.