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It’s important to select the best metering mode for your camera, and to understand how it works. If your camera is consistently getting exposure wrong it may be because you don’t understand how the selected metering mode works. You may also have accidentally knocked a dial and changed the metering mode without realizing it.
Other reasons that your camera may get exposure wrong are covered in Why Cameras Get Exposure Wrong
Metering modes vs Exposure modes
It’s also important to understand the difference between metering modes and exposure modes, as they aren’t the same.
An exposure mode sets the exposure settings (aperture, shutter speed and ISO) for you, or gives you full or partial control over them. Most cameras have shutter priority, aperture priority, manual and program exposure modes, for example (although the names can differ).
The metering mode determines how the camera measures the quantity of light coming through the lens. It doesn’t tell the camera which aperture, shutter speeed or ISO to use, only how much light there is to work with.
You can learn more about exposure modes in How To Choose An Exposure Mode On Your Camera
Most digital SLRs have the following exposure modes.
Center-weighted average metering
Center-weighted average metering works on the basis that your subject is most likely to be located in the center of the frame. The camera measures exposure from the center of the viewfinder.
This diagram shows how it works. The gray circle shows the area metered by the camera.
This is the sort of photo that center-weighted average metering is suitable for. The subject is central and there are no large bright areas likely to influence the camera’s meter into under-exposure.
If the subject is off-center, you can measure exposure by pointing the center of the viewfinder at the subject. Hold the shutter button half-way down to lock in the exposure settings, and reframe.
For example, if you’re shooting a scene that contains a bright sky, you need to point the camera down to exclude it, hold the shutter button half-way to set exposure, then recompose.
This is the type of photo where the bright sky, which takes up half the frame, gives problems with center-weighted average metering.
This metering mode has been around a long time. If you own an old film camera it may be the only metering mode it has. Center-weighted average metering is predictable and easy to use once you understand how it works.
In spot metering mode the camera takes an exposure reading from a circle in the center of your viewfinder.
This diagram shows the metered area. There may be a circle in the center of the viewfinder to show the area covered by the spot meter.
Using spot metering takes practice. If your camera is behaving strangely in regards to exposure, it’s worth checking that you haven’t accidentally set it to spot metering mode.
Remember that cameras measure reflected light, and that the camera expects the tones within the area that it meters to average out to mid-gray.
If you point the spot metering circle at a tone that is lighter or darker than mid-gray, the camera will give you an incorrect exposure reading.
For example, in a photo like this you would different exposure reading if you pointed the spot metering circle at the white sign, than you would if you pointed it at the red wall.
Here are three ways you can use spot metering.
1. Point the spot meter at something in the scene that is naturally mid-gray, such as grass.
2. Take the exposure reading from an 18% gray card placed in the scene.
3. Take an exposure reading from a subject that’s heavily backlit, or from a bright subject positioned against a dark background (such as a performer in a theatre or a singer at a concert).
As you can see, spot metering is a lot of work. It makes sense to use it only when you really have to, and when you understand how to use it.
Center-weighted and spot metering both take an exposure reading from the center of the frame. The obvious flaw with this is that most photographers prefer to place the subject off-center. The process of metering with the subject in the center of the frame, then recomposing, slows you down. A better metering mode is required.
That brings us to evaluative metering*, the most advanced metering mode on your digital camera. It has been developed by camera manufacturers to make it easier to measure exposure with off-center subjects, like this portrait.
The camera divides the viewfinder up into zones. It compares readings from each zone to come up with a suggested exposure setting.
As cameras get more advanced manufacturers pack more zones into their metering systems. The Canon EOS R5 has 384 metering zones, the Fujifilm X-T5 has 256 and the Sony A7 IV has an incredible 1,200 zones. I’m not sure that more zones equals better exposure, but it shows how sophisticated cameras are now.
The camera weights the exposure reading towards the active autofocus point (or points) as they are likely to indicate the location of the main subject. It also takes into account readings from nearby zones and analyzes the contrast of the scene to come up with a suggest exposure setting.
Each camera manufacturer uses a slightly different process in their evaluative metering modes. While they don’t release precise details of how their systems work, there’s normally a guide in the instruction manual. It’s well worth a read so you understand how it works on your camera.
Evaluative metering really comes into its own when you are using an automatic flash to light the subject. Modern cameras are capable of analyzing the flash to subject distance and balancing that with ambient light levels (as in the portrait below). It would take you much longer to work out all that stuff yourself.
* Note: Everybody uses a different name for this metering mode. Canon and Sigma use the term Evaluative metering. Nikon uses matrix metering, Sony and Pentax use multi segment metering, Fujifilm uses multi metering and Olympus uses digital ESP metering.
Which metering mode should you use?
My advice is that you take the simple approach to exposure. Set your camera to evaluative metering and forget about it. I haven’t used a metering mode other than evaluative metering (on my Canon EOS cameras) or multi metering (on my Fujifilm cameras) for years. As far as I’m concerned the others are redundant.
The other big benefit of evaluative metering is that it’s by far the best metering mode to use with automatic flash.
Evaluative metering isn’t magic. It’s more accurate than center-weighted metering, but it still gets exposure wrong if the scene doesn’t average out to 18% gray. It also underexposes your photo if there’s a lot of bright sky in the frame. Pay attention to your histogram and learn how your camera reacts in different situations.
For example, I know that if I’m photographing a low contrast subject in the shade, then my camera tends to underexpose the subject by up to a stop. In this situation I set Exposure Compensation to +1.0 to counter it. With practice and experience you’ll soon learn what to expect from your camera.
My ebook Mastering Exposure gives you the knowledge you need to get the correct exposure every time you take a photo. Reading this ebook helps you master your camera’s exposure modes and metering tools. You’ll learn why your camera gets exposure wrong, and how to put it right when it does.
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