METERING MODES
Why do cameras have different metering patterns, and what do they actually do? Rod Law ton explains
Getting the exposure right is both an art and a science. The art lies in working out how you want your picture to look and the interplay of light and shade, while the science is getting your camera to measure the light in the scene in the way you want.
To help measure and understand the light, cameras come with a variety of metering modes. The default option is multi-pattern metering, and most of us probably use this all the time without even thinking about it.
But while this is the most sophisticated way of measuring the light, it’s also the one where the camera’s own algorithms play the biggest part. Camera makers have gone to a great deal of trouble to train their cameras to understand and deal with a variety of lighting conditions, so that most of the time they will arrive at a very good outcome.
However, it’s not clear how they’ve done it, and results may vary with even small changes in framing. So while it’s very clever, multi-pattern metering is also very difficult to second-guess. It’s not always predictable. You can just use regular multi-pattern metering and your camera’s EV compensation control to make your pictures look right. But this won’t teach you very much about exposure or what’s happening with the light in the scene. This is why more-experienced photographers often prefer to swap to a simpler or more precise metering mode that puts all the control in the hands of the photographer.
Just about all serious cameras will offer multi-pattern metering as a default, with centre-weighted and spot metering as options.
But these are not the only metering modes you might encounter.
Depending on your brand of camera you may get other metering options which are even more useful.
We’ve shown what these do and how they work below, using generic icons that you’ll probably recognise from your camera, though they can vary from one model to another.
METERING PATTERNS EXPL AINED
Multi-pattern metering (or ‘Evaluative metering’ for Canon users) measures the light at multiple points across the scene and then uses algorithms to match the light distribution to a database of typical scenes. This is how Nikon used to do it at least – camera makers are typically quite coy about technical details like this.
The camera averages the light levels across the scene but assigns more prominence to the central area. On many more advanced cameras you can change the size of this central area. Centre-weighted metering is like a blend of average metering and spot metering so that you get some of the advantages of both without the weaknesses.
