Should you bother to learn about metering modes? I’m confident I can sell you on it. Your camera’s automatic metering will only carry you so far. As your digital photography ability grows, you’ll start to feel frustrated in scenes with mixed light. Learning metering modes is the key to making tricky light conditions seem much less intimidating.
Let’s jump right into this beginner’s guide to metering modes.
What is metering?
This is vital to understand before you learn about your camera’s individual metering modes. “Metering” means taking a light reading. A properly exposed image is made up of three tones of light: the shadows, mid-tones, and highlights.
The image below demonstrates these three tones well. The forested hills in the foreground and dark cloud represent the shadows, the temple roof and figure represent the mid-tones, and the bright clouds represent the highlights.
Your camera has an ingenious tool called a light meter that enables it to determine a correct exposure with a balance of shadows, mid-tones, and highlights. You’ll see it at the bottom of the frame when you put your eye to the viewfinder.
Taking light readings from the scene
Your camera’s metering modes control which part (s) of the scene your light meter uses to take a reading. Consider the example below. If you were to meter only off the dragon and take the photo, the dragon would be correctly exposed. However, the sky would probably be too bright.
Alternatively, if I was to meter only off the sky, the sky would be correctly exposed but the dragon would be a bit too dark. However, if I metered from a wider section of the scene, I would get a more balanced exposure.
The four main metering modes
Now, let’s get down to the crux of the article. Here, I’m going to explain what each of your camera’s four metering modes does and how this affects your images.
But before we begin, a note about how your camera meter works. Very bright and dark tones can trick your light meter. Why? Because it is designed to bring every tone to something called “18% gray.” Imagine a snow-covered mountain or a jet black car. Would you want your camera to correct these tones to appear 18% gray? Or would you want their tones to be rendered as truly as your eye sees them? The answer is obvious, but not to your light meter.
So it is your job to review your image on the histogram and decide if it is correct for your scene or not. If it’s not you can use Exposure Compensation to adjust it (when shooting in Aperture or Shutter Priority modes).
Evaluative (or Matrix) Metering Mode
Evaluative metering is the natural mode to explain first because it’s the one your camera uses as standard or default. Your light meter takes a reading from across the whole scene. With that information, your camera’s onboard computer makes multiple calculations to determine a correct exposure with balanced highlights, mid-tones, and shadows.
Center-Weighted Metering Mode
Imagine that you’re now zooming into the frame slightly. Whereas Evaluative Metering mode reads the light from across the entire scene, Center-Weighted Metering mode reads light with a preference towards the middle. It still reads from a large proportion of the frame, just not the whole thing. This varies between camera manufacturers, but it’s usually between 60 % and 80 % of the frame.
Partial Metering Mode
If Center-Weighted metering meant zooming in a little, Partial Metering is a huge jump inwards again. This time, your light meter will read the light from an area the size of 6-15 % of the center of the scene, depending on your camera manufacturer.
With the Varanasi boatman above, I was shooting in Aperture Priority mode. I aimed my center focus point at his face before composing the shot. This allowed my camera to read the light from 10 % of the frame around his head.
Then, I used the exposure lock button (read that article if it’s the first time you’ve heard about it). Note that this is for use mainly with Aperture or Shutter Priority mode. With this button held down, you lock in the exposure and can recompose the shot without the settings changing.
Spot Metering Mode
The final push inward; Spot Metering mode reads light from between 1-5 % of your scene. I personally use Spot Metering mode more than any other, but it may be more challenging for you if you are just learning about your camera and metering.
It is particularly useful to use spot metering in conjunction with the exposure lock button and the center AF point selected. Aim the center point of your viewfinder at the subject or light source to meter from it. Lock in the exposure and recompose, then focus and shoot.
I find that spot metering mode is goodfor portraits and getting the correct skin tones. Also, I use it for specific light sources, such as a beam of light through a window, but only when I’m also happy for other regions of the photo to be underexposed. I do not recommend using it for landscapes unless you are looking to experiment with silhouettes.
The next step on from here is full manual mode, in which the exposure lock button is not required. But first, master metering modes using Shutter and Aperture priority modes.
Now that you’ve learned about each metering mode, get out your camera and go practice. Don’t forget to share your thoughts and images in the comments.