Why matrix metering is the worst kind of metering ever.

For me, matrix metering is a black box. Matrix metering meters the whole frame in different sections and compares it to a pre-determined set of scenes. The computer in the camera then makes it's best guess as to what is actually being photographed and adjusts the exposure accordingly.

For example, the scene has a big bright spot in the middle and everything else is dark. For the sake of discussion, let's assume that the background and the bright thing differ by 4 zones. The camera might guess that you are doing a portrait on a black background, it also assumes that a face is supposed to be in zone VI, so it returns an exposure that would put the bright area in zone VI instead of the normal zone V and gives you the exposure. All is good. The face is not gray, as it would be if you used the other "dumb" metering modes and the background is black at a nice zone II, hiding any creases and patterns that you might have in the black background cloth.

But what if I am actually photographing a lamp with a lamp shade against a wall and I would love to see the intricate pattern on the wall paper? The camera would still put the lampshade in zone VI and letting the wall fall into zone II. I would get a black wall with only minute details of the wallpaper design. Not what I wanted. It would be better to sacrifice some detail in the lampshade and get the details of the wall instead. So I would place the wall in zone IV and the lamp would fall into zone VIII. That gives me the shadow detail of the wall at the expense of loosing detail in the lamp shade.

The biggest problem of matrix metering is that you never know what zone it placed the subject in and most of the time you don't even know what part of the scene the camera thought was the subject.

I'll put this example here to get ahead of myself and bring everything together, i.e. how the inherent limitations of digital manipulation would affect exposure decisions. Consider the case where I wanted detail both in the lampshade the wall, I would instead place the wall in zone III letting the lamp shade fall into zone VII knowing that I have a better chance of getting usable detail by adding digital light to the zone III part than pulling the highlights of the zone VIII part which usually gives grays instead of the real colours of the lampshade.