Last updated on August 16th, 2023 at 04:29 pm
Understanding camera metering modes is integral to understanding the basics of exposure. This is an often-overlooked setting on your camera that can make or break your images. Let’s master this aspect.
The first time I ever used a digital camera, a Nikon D7000, I started shooting pretty much the same way as everybody else does. Setting the camera on the P mode and firing away. I realized pretty much straight away that there was something wrong with the way I was shooting.
Some of my images would turn out to be wrong in terms of exposure. Many would be underexposed, while others would be grossly overexposed. This happened far too many times and especially when I was shooting in situations where there was a lot of difference in brightness across the frame.
Typical situations would be when I was shooting portraits, especially if the background was brighter than the subject’s face, or vice versa. Also, when shooting landscapes the highlights would be blown out, and there would be no way to recover details from those areas.
This problem lingered on when I transitioned to artificial lights. Often when I was using a spotlight set up the resulting photos would have the shadows completely crushed while the subject’s face was properly exposed. At other times the subject’s face was blown out while the background turned out to be properly exposed.
Now, there are a lot of things that contribute to these problems, and metering modes alone cannot be held responsible for all of them. Having said that, understanding how metering modes work and knowing when to use which particular metering mode can help a long way in overcoming these exposure issues.
Perhaps in a different discussion, I will talk about some of those other aspects, such as exposure compensation, using highlights warning, using shooting techniques such as exposure stacking, and of course a general overview of post-processing techniques.
For this discussion, I will limit myself to just discussing what camera metering modes are, when to use a particular metering mode, and how and when to override metering modes for specific shooting requirements.
Table of Contents
What is Metering in Photography?
If you have looked through the viewfinder of a mirrorless or a DSLR camera you must have noticed a metering bar at the bottom of the viewfinder. Depending on what you are looking at and how bright or dark the scene is the indicator on the metering bar would slide left or right as you move your camera and recompose.
What’s happening is that the camera is constantly monitoring the light coming through the lens and evaluating the brightness of the scene and seamlessly informing you how much over or under-exposed the shot would be based on the camera settings that have already been applied.
How does it do that?
A typical camera sensor is programmed to infer an average reflectance of 18% to be a normal exposure. In other words, if a scene is too bright the camera would determine how much overexposed it is and therefore how much the exposure should be brought down to match that 18% average exposure.
The 18% Grey Paradox
You will hear the term “18% grey” quite often in photography. It is considered an average exposure based on a given lighting condition.
Now, there is something inherently wrong with the way digital cameras meter a scene. You see, digital cameras meter a scene based on reflected light. So, if your frame is dominated by brighter tones the camera will meter it to be a bright scene and try to undercompensate.
In the same way, if a scene has a lot of darker tones the camera’s metering system would determine it to be very dark and then try to overcompensate to make it brighter and match the 18% average exposure.
This is the reason why when you shoot a scene that is predominantly white it turns out to be grey, or as we popularly call it in photography – “middle grey.” And the same way when you shoot a scene that is predominantly black it also turns out to be grey.
It is the inherent fault in the way the camera metering system is programmed. It always takes into account the colors around the subject, and how bright or dark they are to determine the correct exposure value.
So if the background is brighter than the subject the metering mode of your camera will give you a certain exposure value. Then again if the background becomes darker it will give you a completely different set of values.
This can be confusing for somebody who’s just beginning in photography. Ideally, if the lighting is the same and the subject is the same the meter should give you the same exposure values. But it does not.
And it gets worse. Depending on the metering mode that you select it can further skew its recommendations.
This is the reason why a lot of studio photographers would use an external light meter and not depend on the metering system of their camera to set their lights.
An external light meter measures the light in a scene using the incident light system. So it tends to be a lot more accurate than the camera’s metering system.
All you have to do is enter the ISO value and one of the other two parameters of exposure (aperture, shutter speed) and click to test the ambient lighting. The light meter will give you a reading for either the aperture value or the shutter speed depending on what are the two parameters you have entered.
From there on all you need to do is enter the values into your camera in the manual mode and you should be able to get a perfect exposure every time you click the shutter.
I’ll detail the process of metering with an external light meter in a separate discussion.
What are the Camera Metering Modes?
A camera’s metering modes take into account how much of the scene the camera is going to consider for metering.
Although we don’t have it in our hands to change the way a camera’s metering system works, we can certainly decrease the gap between what the camera thinks is the right exposure and what we feel as photographers is the right exposure by choosing the right metering mode.
Let’s now understand what are the different metering modes.
Different Types of Metering Modes
Depending on the camera make and model that you are using you may have access to several metering modes. Nikon cameras, for example, traditionally had three metering modes – matrix, center-weighted, and spot.
Canon cameras, on the other hand, have four metering modes. Apart from the three that Nikon cameras have the fourth one is the partial metering mode.
The latest generation Nikon cameras come with an additional mode known as highlight-weighted metering mode.
All the other camera brands have more or less the same types of metering modes except they are named differently.
In this section we will learn about the following metering systems:
- Spot metering mode
- Evaluative/Matrix Metering
- Center-weighted/Average metering mode
- Partial metering mode
- Highlight-weighted metering mode
Spot Metering Mode
Spot metering mode uses a small area in the form of a spot, no bigger than 1.5% of the frame that you can see through the viewfinder. This metering mode uses the active AF point to meter a scene.
Because spot metering mode uses the active AF point it is ideally suitable for off-center compositions.
Spot metering mode is ideally suitable in situations where a subject occupies a small part of the scene. E.g., if there is a small bird in the frame and you want to accurately meter off of it, spot metering is your best bet. Like in the below case.
Spot metering is also useful when you want to ignore the brightness information across most of the frame and just focus on a small part of the scene.
Because spot metering takes a precise sampling of the scene it is a lot more accurate than partial metering in certain situations.
That said, spot metering can also result in wildly incorrect metering results if you use it in situations where the frame is dominated by a single.
E.g., if you are photographing a groom wearing a black tuxedo and standing against a dark-colored wall, it is likely going to meter the scene too dark and therefore apply the 18% grey average.
Evaluative/Matrix Metering
Evaluative or matrix metering is the most commonly used metering mode. This mode can be used in a wide variety of shooting situations. Evaluative or matrix metering pretty much covers the entire frame by taking a series of readings and then averaging those readings to give you an average exposure value.
As you can imagine this particular metering mode is ideally suitable for landscape, street, travel, and other photography genres where the entire frame is important.
Evaluative metering cannot be used in all kinds of photography genres though, particularly where there is a lot of difference in the brightness levels across the frame or where only a part of the image is illuminated and the rest of the frame is dark. Matrix metering is also unsuitable for backlit situations.
For me, this particular metering mode is only suitable for landscape photography because that is the only time when I would want an average exposure. Even then I tend to watch out for the highlights and use exposure compensation to ensure that I’m slightly under the advised exposure value.
Center-weighted/Average Metering Mode
We can compare center-weighted or average metering mode as a combination of evaluative/matrix metering and spot metering. This is because in center-weighted metering the whole of the scene is considered for determining the correct exposure value, but at the same time, greater emphasis is placed on the center part of the frame.
Please note, that unlike in spot metering where the focusing point is considered the cue for determining the exposure value, in center-weighted metering mode, the emphasis is always the center of the frame.
This is why it is particularly useful for capturing images where the subject is at the center of the frame. This mode is my preferred mode for natural light portraits, shots of wildlife, and a bit of flower photography.
Learn more about wildlife photography by checking this resource out.
Partial Metering Mode
Partial metering mode is available on Canon camera systems. This mode isn’t available on Nikon systems. It uses only a part of the frame to determine the correct exposure value.
As the name suggests partial metering mode takes into consideration only a small percentage of the view through the viewfinder. Partial metering uses only about 6-10% of the view through the viewfinder.
The difference between spot metering and partial metering is that in the former a sampling area of 1.3 – 1.5% of the viewfinder is used, while in the latter a larger sampling area is used.
This metering mode is also suitable for portrait photography. Particularly for situations where the background is considerably brighter than the subject.
Highlight-Weighted Metering Mode
The highlight-weighted metering mode is a new metering mode introduced by Nikon. As the name suggests this metering mode is aimed at assisting photographers by properly metering for the highlights and ensuring that they are not blown out. As you are aware it is nearly impossible to recover details from blown-out highlights.
This metering mode is ideally suitable for situations where you are using a spotlight or any kind of hard directional lighting to focus on a particular aspect, such as the face of a subject.
Highlight weighted metering mode will come in handy when using artificial lighting sources such as studio strobes and speedlights.
Why Should You Adjust the Metering Mode of Your Camera?
Changing the metering mode of your camera is like giving the built-in metering system a cue as to what the scene is all about and how much of the frame should be taken into consideration for determining the correct exposure value.
Choosing an incorrect metering mode will likely result in an exposure that is over or under what is the right exposure.
Which Mode to Use in Different Situations?
I have already discussed in some detail the various shooting situations where a particular metering mode is more likely to give you better exposure.
Among all the metering modes I feel spot metering is the most difficult to work with. The reason is spot metering only takes into account a small part of the frame which is often no more than 1.5% of what you see through the viewfinder. Since spot metering is heavily dependent on the active AF point, choosing the wrong AF point means you are likely going to skew the exposure either to the left or to the right.
This is a major reason why I do not recommend spot metering mode to photographers who are just starting. It’s very difficult metering more to work with and often results in incorrect exposures.
As I have already mentioned above, the best user-case scenario for matrix metering is a scene that is uniformly lit. So there is no huge difference in brightness levels across the scene and the camera can meter it well enough.
You could perhaps also use matrix metering in scenes where there is a lot of difference in brightness across the frame. The matrix metering mode does a good job of averaging everything out. However, please note that averaging exposure is not always the best approach in photography. An average exposure will likely result in an image that is low in contrast. You have to take that image and further post-process it to render the final look.
For scenes that have a lot of difference in brightness levels, I would recommend that you use the spot metering mode and choose one of the brightest areas of the frame to meter off of. For Nikon users, you can also use the highlight-weighted metering mode that I have explained above.
Matrix metering is by far the easiest of metering modes to work with because it by default takes into account the entire frame. Because of that, it’s very difficult to get things wrong, unless there is a lot of difference in brightness levels across the frame.
Overriding the Camera Metering Modes
The need to override the metering modes comes from the fact a camera’s built-in metering system is not exactly the perfect way to meter light. Algorithms have changed over the years but fundamentally it still is pretty much the same.
Even with spot metering, which I consider to be the best metering mode you will come across a situation where your camera gets it wrong, thus making it pertinent to override the recommendation of the camera’s metering system.
I mentioned the snow scene earlier in this discussion. It is a classic example of a situation where the camera’s metering mode can get things wrong. Usually, when you are shooting in a very bright scene – such as a snowcapped landscape, the camera will see all that bright white and it will meter the scene to be too bright. The 18% grey algorithm will kick in and it will try to underexpose the scene and in the process make it appear middle grey.
Similarly, when you are photographing a subject wearing black clothes standing against what is essentially a dark background, it will easily spoof the metering system to think that the scene is too dark. Again, the middle grey algorithm will kick in and the black will appear grey in the final picture.
So, it becomes necessary to override the metering system of your camera from time to time.
Using the Exposure Compensation Technique
The simplest way to override the camera’s metering system is by using the exposure compensation technique.
Let’s first understand what exactly is the exposure compensation technique. It is basically a way of overriding the camera’s metering system by telling it that you want to under or overexpose the scene based on the readings that the camera thinks are the right exposure value.
How do you achieve that?
You use a combination of buttons and dials on your camera to achieve exposure compensation. It’s usually a button that has a plus and a minus sign on it. You press and hold that button and then turn one of the command dials to apply exposure compensation.
The exact combination of buttons and dials and the symbols that identify the exposure compensation button will vary based on the camera make. So please check your camera manual for the exact details.
How Much Exposure Compensation Should You Dial?
The application of exposure compensation can sometimes seem like guesswork. If you are just beginning to play with the metering modes and exposure compensation techniques, it will take some time to get the perfect results.
It may even seem like a non-exact science. I would recommend that you play around with the Sunny 16 Rule, understand the fundamentals that govern that rule and have a basic understanding of exposure values so that it becomes a lot easier for you to apply those principles out in the field.
Let’s break it down in simpler words.
When we talk about exposure values we’re talking about a combination of aperture and shutter speed. Any combination of those two values will give you the exact same exposure, considering that you do not tinker with the ISO value and the lighting stays the same, there is no change in the subject, and basically, nothing else changes.
Let’s say in a situation like this you know for sure that a combination of f/4 aperture with a shutter speed of 1/500 sec will give you a good exposure. Let’s also consider that the ISO value is 100.
If you now decide to drop the aperture to f/5.6, so that you’re able to get a larger depth of field, your shutter speed must compensate for that loss of light. In other words, your shutter speed must slow down to let in more light.
Now we know that there is an inverse relationship between shutter speed and aperture. That means a drop of one stop in aperture value must be compensated by an increase in one stop of shutter speed value. So, in this case, your new shutter speed should be 1/250 sec.
F/4 at 1/500 sec and f/5.6 at 1/250 sec will give you the exact same exposure.
Coming back now to the Sunny 16 Rule, it states that if it is really bright outside and you’re shooting at ISO 100, at an aperture of f/16, your shutter speed should be the inverse of your ISO value. That means 1/100.
Now, if I take that as our starting point, regardless of the subject that I’m shooting and the color of the background, I can apply the exact same exposure value to get a perfect exposure. Which in this case is f/16, ISO 100, and 1/100 sec shutter speed.
So, even if I do not have an external light meter in hand I can still get a perfectly decent exposure just by calculating this on the fly in my head out in the field.
What if I don’t need a large depth of field?
This is a valid question and in certain situations, an aperture of f/16 may be an overkill. For example, you might be shooting a portrait session and you want to blur things in the background by using an aperture of f/2.8.
All you have to do is count how many stops from f/16 to f/2.8, which in this case is five stops, and then adjust your shutter speed accordingly. So your aperture becomes f/2.8 and your shutter speed becomes 1/3200 sec. Easy peasy!
Conclusion: Camera Metering Modes are Just a Guideline
To round off this discussion I’d like to reiterate that metering modes are just a guideline for you to set your exposure correctly out in the field. It’s just a guideline to get you into the ballpark. From there on it’s all your experience and the tools you use that determines if you are going to nail the exposure every time.
Getting the right exposure in any kind of lighting is a challenge. Considering that the metering system of our cameras is inherently flawed, it becomes imperative that you know when to use your judgment to override the metering system and how.
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