The D7200 offers three exposure metering patterns. Matrix metering is the default, and this analyses areas across the whole scene and compares them to an internal database of scene types to arrive at the ideal exposure. It works well for most of the time, but because its operation is complex it’s quite difficult to anticipate those occasions when it might not work so well.
This is why centre-weighted metering is also popular. This is a simpler, older system that measures the average light level across the scene but with a greater weighting towards the centre – hence the name. To change the metering pattern, hold down this button and turn the rear command dial .
The third option is spot metering. This takes a light reading from a very small area of the scene (corresponding to the current autofocus point) and bases the exposure on that. It can work well for spotlit stage performers, for example, or other subjects which are in different lighting to their backgrounds.