Your camera probably has at least three or more light metering modes.
Evaluative Metering, Matrix Metering, Center-weighted Metering, Partial Metering, and Spot Metering.
But what do they mean? How are they different, and which one is right for you?
First, you should understand that there are two different ways to measure light for proper exposure:
- Incident Metering, which measures the light that falls directly on the meter.
- Reflective Metering, which measures the light that bounces off of your subject.
For example, If you’re outside and measuring the sunlight bouncing off of your subject’s face (which you can do with your camera), this is reflective metering.
Measuring the sunlight itself for exposure (which must be done using a light/exposure meter) is incident metering.
The light meter in your camera measures light using reflective metering. So, whatever you point your lens at, the meter will measure that specific reflection of light.
So how does each in-camera metering mode affect this measurement? Let’s walk through the most common ones.
Evaluative or Matrix Metering Mode: This is the default mode for most all metering cameras with multiple options, and if you’ve never touched the metering mode it’s most likely this one that you’re shooting in. This mode may be called one or the other, based on the camera manufacturer you’re using. For instance, Canon calls this mode “Evaluative,” whereas Nikon refers to this mode as “Matrix,” (and there are still others, such as “multi-segment,” “multi,” and “ESP”), but they mean the same thing.
In evaluative/matrix mode, your camera evaluates all of the highlights and shadows in the entire frame with a slightly greater emphasis on the selected focal point. What’s great about this mode, and why it makes sense for it to be the default for your camera, is that it’s most likely to ensure an even exposure of your image in most scenarios.
Center-weighted Metering Mode: As with evaluative/matrix metering, this mode also evaluates the entire frame but with one key difference; It does not take the focal point into account and instead emphasizes exposure toward the center of the image.
Spot Metering Mode: In this mode, your camera will measure only the light at the selected focal point and will not take any other light in the frame into account.
This mode might require a bit more work or thought, but it is great for more complicated lighting situations. Such as, when you’re shooting a back-lit subject. Using spot metering, you can precisely meter your subject for exposure without your camera taking the bright light behind them into consideration. Another example would be shooting a live band in a dark venue. Using spot metering, you will be able to more easily evaluate the exposure of the performer without the darkness surrounding them, affecting the light reading.
For Canon users, there is also Partial Metering Mode. It’s basically like spot metering but covers a slightly larger area.
Which camera metering mode is right?
Like so many other tools in photography, this is not the thing that is going to make or break your images. No matter how “smart” cameras get, all of these tools and options are only as good as the hands that use them.
If you just want to set it and forget it, leave it on the default mode. It’s going to serve you well, almost always. I would encourage you to play with spot metering. It’s the mode that I shoot in most of the time. I often enjoy complex lighting situations, though, so it makes sense for me.
In general, as long as you’re shooting in RAW, it’s a good rule of thumb to err on the side of overexposed. An image that is a little overexposed is much easier to correct than an underexposed image. Just make sure you don't blow out your whites.
Something else to know about your in-camera meter (and reflective metering in general), is that your meter reads and balances for neutral gray. The meter doesn’t see color but tonality.
If you’re photographing a white dog against a white fence, your in-camera reflective meter will try to balance them both to neutral gray, which will give you an improper reading and the image will be underexposed.
Shooting a black dog against a black fence would pose the same problem but in reverse. Your camera would try to balance the scene for neutral gray and give you an overexposed image.
There are two ways to work around this. The general method is to increase your exposure two stops for the white dog and decrease your exposure two stops for the black dog.
The other and more specific way would be to check your exposure using a neutral or 18% gray card. (Checking exposure with a gray card would utilize the spot metering mode.)
If you set your exposure based on the exposure of the card, then all images taken in that same light with those same settings will be properly exposed for shadows and highlights.
Carrying and using a gray card in every scenario may not be necessary, but it certainly wouldn’t hurt to have one on hand for super bright or dark situations.
As always, keep practicing, keep playing, show us what you create, and let us know if you have any questions!