Understanding Metering Modes: Spot vs. Center-Weighted vs. Matrix

You may have seen something called ‘Metering Mode’ on one of your camera’s menus, and wondered what it is and what it does. It’s also called ‘Camera Metering’, Exposure Metering or just ‘Metering’.

You may be wondering why this matters to you, but it’s important that you understand what each metering mode does, because it helps you to control exposure and take photos in unusual lighting situations.

Remember in the last article we talked about using your camera’s exposure meter to help you figure out the correct exposure? There are different modes you can have your camera’s metering on, and each one has a different way of measuring the light to find your optimal exposure.

We’re going to look at the different ways each of the metering modes works, and when you might want to use each one.

Spot Metering

Spot metering, as the name suggests, only evaluates the light around your focus point and nothing else. It measures a single, small zone and calculates the correct exposure measured on this area and nothing else.

If your subject doesn’t take up much space in the frame, and is back-lit, spot metering is the best mode to choose for this scenario. The exposure is worked out from your focus point, and it will ignore the bright light behind your subject, even on a sunny day. If you took the same shot with center-weighted or matrix metering modes, your subject would probably come out as a silhouette.

You can also use spot metering for a bright subject against a dark background, such as the moon in the night sky. It will only measure the brightness of the moon, not the sky around it.

Because the area being metered is around your focus point, you can change the focus to a different area of your image and thereby change the exposure measurement, depending on how light or dark it is.

Center-Weighted Metering

Center-weighted metering uses the center of the frame to base the exposure on. It evaluates the light in the middle of the frame and surroundings, ignoring the corners. It doesn’t change position when you change focus points, unlike spot metering, so it will always base its reading on the center of the image.

Center-weighted metering works well when you want to utilise the center of the frame, such as in a close-up portrait or abstract image. If your subject is backlit like the example used with spot metering above, this metering mode will expose the center of your image correctly, but the background will probably be horrendously overexposed.

Matrix/Evaluative Metering

Matrix metering, which is also known as evaluative metering on Canon cameras, and by yet still more different names by other camera manufacturers, is the default setting on most DSLR’s. It divides the frame up into separate zones, and analyses all the light data available in these zones. By reading this information, it aims to produce a balanced exposure over the whole scene.

Unlike the other two modes, matrix/evaluative uses the whole frame to determine how it will suggest optimum exposure. Like spot metering, matrix/evaluative is affected by the focus point your camera is set to. Basically, the system reads the information from all the zones, then checks where you have set focus to. It then marks that area as the one of most importance compared to the other zones.

Possible Problems

Built-in camera meters only measure reflected light, unlike hand-held meters which measure incident and reflected light. These days, most built-in camera meters are very accurate, but there are scenarios when it becomes confused. We covered this in the last article, but I’ll briefly remind you again that tonal extremes often fool the meter: bright white scenes, or dark black scenes.

It doesn’t matter what type of metering mode you have your camera set on, these extreme light and dark scenes will still come out badly exposed, so you will still have to adjust your exposure to compensate.

Final Thoughts

So, that’s what your camera’s metering modes do! It’s worth getting to know them, so you can decide which mode to use in different situations.

Dig your camera manual out, or look online, and find how to change the metering modes. Then start playing around with them, taking photos of the same thing in the same light, but changing the metering mode. For instance, try taking a photo of something that’s backlit by the sun in matrix mode, then take the same image in spot metering mode. Do you see the difference?

Try to work out which metering mode will work best for you in different scenarios, and start paying closer attention to the light in scenes you want to shoot. Think of what you want to achieve with the light in your photo, and see if you can visualize what each metering mode will do with that light. Will it give you the image you want? Would you be better changing it?

The metering modes are one of those small but important functions that are often overlooked by photographers. I personally know several who have never moved theirs off the default mode since they bought the camera years before! They are happy doing that, but understanding metering can make a significant difference to how you shoot your images.

Will you be experimenting with different metering modes, or would you be happier to stick to the one you’ve always used up until now?

Next time, we’ll be looking at understanding dynamic range in photography.