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Why You Need to Understand Camera Metering

Have you ever taken a picture on a digital camera, looked at the monitor and thought, “Why is it so dark?” I have two words for you – camera metering!

learn to out think your camera
Photo by Pok Rie

Do you want to take photos that look more like what you imagined they would look like in your head? Do you wonder why your pictures don’t come out the way you thought they would? Well, I can tell you who the culprit probably is – your camera! Your camera is DUMB! Yes, it is a sophisticated piece of equipment that can process complex image data in fractions of a second, but does it know what picture you want to take? No. It does what it is told.

You Need to Be Able to Out Think Your Camera’s Internal Metering System

You, the person taking the picture, need to out think your equipment if you want to take consistently better photos that match up to what you envision. You need to consider the light, your subject, and what ‘end result’ you are looking for. To help with that, I will post a series of articles on ‘out thinking’ your camera. First up, metering modes! Metering is how your camera determines the exposure settings for a picture when you have your camera set to anything other than ‘Manual Mode’. You have probably seen this icon on your camera…

But do you know what it means? By clicking on the button on your camera that has this icon next to it (it is in different places depending on who manufactures the camera and what model it is), you can switch back and forth between the various metering modes on your camera. Do you know what all the different metering modes available on your camera actually do and what situations they are best suited for? If you do, great! If not, keep reading…

Understanding Camera Metering Modes

Your camera has a variety of different modes to determine the exposure for the picture you are taking. The first step to choosing the right one is understanding how each of them works.

Evaluative (Matrix) Metering Modecamera metering evaluative mode

The default metering mode for your camera, and if you are in ‘auto’ mode it can be the only option. In this mode, your camera read light in the entire frame, weighing the area around your current focus point most heavily. You will probably have your camera set on this mode most of the time.

Partial Metering Modecamera metering partial metering

This mode measures the intensity of light in a circular area taking up approximately 8 to 12% of the center of the frame, regardless of where the focus point is set.

Spot Metering Mode

camera spot metering mode

Similar to the partial metering mode, spot metering measures and even smaller area, about 2 to 4% of the frame, around your focal point. So, wherever you have set your focus, that’s where the camera is going to meter. Now, if you don’t refocus the image but your recompose the image, the camera is still going to meter for that part of the frame when you hit the shutter.

Center Weighted Metering

camera center weighted metering mode

This mode is similar to evaluative metering mode in that it takes the entire frame into account. However, it ignores the focus point and ‘weighs’ the center part of the frame more heavily.

When To Use Each Metering Mode

Each different mode has its own strengths and can be used to greatest advantage in different situations.

When To Use Evaluative (Matrix) Metering

There is a reason that this is the default setting on cameras. It is great for evenly lit scenes where there is not a lot of contrast between the subject and the background. It is also a good setting if you want to take in the entire setting – such as a wedding where there is a great backdrop view and you want to ‘see’ it all. This is, to paraphrase a certain infomercial, the ‘set-it-and-forget-it’ metering mode. If you don’t have a lot of time to think about which mode to use or you are not yet comfortable with the other metering settings, evaluative metering is the way to go.

When to Use Center-Weighted Metering

Center-weighted metering is very good for photos where you are more concerned about the lighting on your subject than that on the background. Remember, you are concerned about lighting your subject, not what is filling the rest of the frame. It has a more predictable output that evaluative metering which means you will end up with more consistent photos. Center-weighted metering is good for outdoor portraits in direct sunlight and high contrast scenes where your subject is taking up at least 1/3 of your frame.

When to Use Partial and Spot Metering

Partial and spot metering are powerful tools. They can be used to great effect in situations where there is a large amount of back light – you can keep your subjects from becoming silhouettes by using these metering modes (depending on the amount of space your subject, or the area you want to expose for, takes up in your frame). They are also effective when taking photos of subjects that are very far away and therefore taking up only a small amount of the frame, as well as high contrast scenes such as a bride in a white or light colored dress against a dark background or a man in a dark suit against a very light background. Spot metering is also highly effective for detail or macro photos.

Want to take great pictures of the moon? Use spot metering! If you try to take a photo of the moon using evaluative metering, your camera is going to try to expose for the black sky as well and you will end up with a white circle with no detail.

Locking Your Exposure

You may be thinking after reading the information above that you can only take pictures using any mode other than evaluative only if your subject is right in the center of the frame. This is not true. Your camera most likely has a function that locks in your exposure for a short period of time. Where to find this function depends on who makes your camera and what model it is (sorry, you will have to do some research on this as there are so many different settings I can’t reasonably discuss them all here). Most DSLR cameras allow you to choose a button on the camera that enables the “AE Lock” function (Auto Exposure), which allows you to lock your exposure settings, usually until you press the button again. Once you know how to ‘lock’ your exposure, you can use any of the metering modes your camera has available to do the following:

  1. Focus on your subject in the center of the frame (I do this because the strongest focus point on any camera is dead center)
  2. Lock the exposure setting using the ‘AE Lock’ function
  3. Recompose the shot, if necessary, and take the picture. IMPORTANT NOTE: If you want to recompose the photo after getting your focus/metering, use back-button focusing (more on that in a later post) or the ‘AF Lock’ function (Auto Focus). Otherwise, recomposing your image may result in your camera refocusing as well.

Bonus Information: TTL Flash

If you are using TTL flash (Through The Lens) or ETTL as opposed to manually setting your flash output power, your metering mode determines how much power the flash will use. Properly metering for the photo you want will help get better results from your flash as well. How about that?

In Conclusion

I hope you found this tutorial helpful. Please let me know what you think or if there are any subjects you would like to see covered in future blog posts by using the comments section below.

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The Nerdy Photographer
The Nerdy Photographer

With more than a quarter century as a professional photographer, The Nerdy Photographer's goal is to spread knowledge and laughter throughout the photo industry. Please follow along on social media and subscribe to the podcast.

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