If you own a DSLR camera, the chances are that at some point you have come across the “meter” functions on there. Most newbie photographers tend to be a little scared to change this from the default setting that it comes in. The reason being that they may not understand what metering is and how to use it effectively for their photography. But it’s actually a really simple function to understand. The hard part is knowing when to use it effectively for your photos. But by the end of this article, you will have a better understanding of what the different metering modes do on your camera.

What is light metering?

Back in the days of film, photographers use to carry a little handy device called a light meter. This device would measure the amount of light available and so the photographer was then able to set their camera accordingly to achieve the correct exposure. The reason for this was that old cameras did not have a built-in light meter like modern DSLRs do.

In DSLRs metering is basically how your camera decided what settings to use to achieve the correct shutter speed, aperture and ISO – in other words, the exposure triangle. It does this by measuring the amount of reflected light from the source you are photographing. So if something is very bright it adjusts your settings so that your photo isn’t overexposed or if it’s dark it’s not underexposed.

Most cameras these days have the following metering modes (some also offer partial metering which is similar to spot metering but just a bigger area):

• Evaluative metering
• Centre-weighted Metering
• Spot Metering

These are the different ways that you can ask the camera to measure the amount of light that is coming from the source.

Evaluative metering

This tends to be the mode that people use most often. It’s also the default metering mode on most DSLR cameras. Evaluative metering means the camera looks at the entire frame that you are looking at and works out what each individual section’s light and dark tones are. It then looks at where the most important element is, in other words where you have focused and makes its setting selection based on all of the information it has gathered. It will of course sometimes make an error where your image is overexposed or underexposed but the vast majority of the time it will be pretty accurate. If you do find that it has made an error you can manually adjust your exposure to combat the issues.

This is the mode that you will probably need to use for most of your photography including for landscape, cityscape and even most of the time, portraits.

Centre-weighted Metering

The reason I stated “most of the time” on the portrait part above is that it isn’t always the right solution depending on the scenario. Portraits are the most obvious time where evaluative metering might have its shortcomings. For example, if you are photographing someone with a strong backlight (i.e. the sun behind them), using the whole frame will mean you will end up with a dark image. This is because all of the bright areas in the image will make the camera think that it has to reduce the amount of light coming in to stop your highlights being clipped. In situations like this centre-weighted metering will mean that the camera will measure the amount of light just in the centre of the image. So, in other words, it ignores all of the bright areas and so you’ll get better exposure for the persons to face.

One thing to keep in mind is that this metering mode doesn’t look at where you have focused like evaluative metering. It just looks at the centre of the frame. The other potential issue with this metering mode is that as the camera adjusts for the light in the middle of the shot (i.e. a persons face) then it’s likely that the surrounding area will be overexposed. You can either zoom in so that your subject fills that frame more, or you can manually underexpose your shot a little to tackle the issue.

Spot metering

As the name indicates, spot metering looks at a small area in the centre of the image and only evaluates that and it and ignores everything else. This mode is very useful where you need more accuracy on where you need your camera to read the light from. As with centre weighted metering, for times where your focus point may not be the centre of the image then this metering mode might cause issues. For example, if you are photographing a scene where your focus is to the side, you will need to use evaluative metering.

As with centre-weighted metering, the issues that you may face will be that as the camera is adjusting for a small area in your frame, the rest of the shot might be overexposed or underexposed. So there will always be times where you may need to tweak the exposure manually to achieve the result that you want.

The camera doesn’t know best

Light meters in digital cameras are very good these days and usually, they are very dependable and accurate in establishing a good exposure for the image. However, they are not always perfect and can sometimes be fooled. For example, let’s say you are using evaluative metering and you are photographing someone dressed all in white standing in front of a white wall. The camera will asses that as a very bright image and so naturally reduce the brightness. This will end up with your white areas having a shade of grey to them because they are underexposed. The way to combat this is to overexpose your image a little to adjust for this camera error. So if you really want to capture great photos learn about each metering mode in more detail and make adjustments when you need to manually. Because the camera doesn’t always get it right.

So there you have it. A short summary of the different metering modes. Hopefully, you have a little more confidence now to try them out and also to learn more about them. Because the more you know especially about their limitations the better you will be equipt to be able to capture great photos.

Photo credits: Kav Dadfar – All rights reserved. No usage without permission. Dreamstime.