Questions and Actions: 18% Gray
The question I am answering this week is one that’s pretty timely given the coming winter. While this topic has absolutely nothing to do with winter and snow, it’s one that gets brought up quite a bit this time of year.
Question
“Some professional photographers talk about things like 18% grey. Is this stuff still relevant to photographers, and if so, is it something we should know and use?” – Mike Cook. Asheville, North Carolina
When you hear people speak about such things as 18% gray, or the Sunny 16 Rule for that matter, understand first and foremost that these are concepts that harken back to the early days of photography. While 18% gray is still relevant because it’s how our cameras read light, the question is does it matter anymore, to us, the photographers behind that camera?
To start with, I guess we should take a moment to describe what 18% gray even is.
18% gray is the dead center mid-tone between featureless black and featureless white and there was a time when photographers actually carried a card around in their pockets just for acquiring their exposure based on this tone.
Everything about the way your camera reads light is built around 18% gray. The TTL (through the lens) light meter you see inside your viewfinder is designed around this one tone of light. Aperture priority, shutter priority / time value (that’s what Tv stands for on some camera’s exposure modes), and auto-ISO are all built around the concept of 18% gray.
The reason that this mid-tone plays such an important role in how our cameras function is because it creates predictability. If you know your camera is exposing whatever tone of light as an 18% gray mid-tone, then you always know what to expect. Are you photographing a black bear, or is it a polar bear? Your camera doesn’t know. It just sees light. Left put to decide itself, the camera will offer up an exposure that gives you an 18% gray polar bear and an 18% gray black bear. Understanding this allowed you to then decide on to add or subtract light from the exposure and render a black bear black or a polar bear white.
Looking through the viewfinder on your camera, you will see your light meter. Some cameras have this across the bottom. Some have them running up the side. Regardless of where it is located or what it looks like, that point smack in the middle of the light meter is always 18% gray.
It doesn’t matter if it’s a deep red cardinal or a mountain bluebird. The color all comes later. The light meter only sees in shades of gray – and black and white, of course.
When we use automatic exposure modes like aperture priority, shutter priority, or auto-ISO, our camera adjusts the exposure so that the dominant tone of the photograph is 18% gray.
In the winter, this means you get gray snow. In the arctic, a gray polar bear. In the forest, a gray colored black bear. That is, unless you adjust your exposure through the use of exposure compensation.
It’s called “compensation” because you are using it to compensate for the tones of light you want to record. Don’t want an 18% gray polar bear? Add exposure compensation. Don’t want 18% gray snow? Just add light via your exposure compensation.
All of this applies to manual exposure as well, of course, so long as you are using your TTL light meter to set your exposure - though this is rarely needed in the field now-a-days because there are easier ways of doing this than worrying about 18% gray if you’re going to shoot in manual mode.
Oh, and just to be clear, if you are using auto-ISO you are NOT shooting in manual – you are still using an auto-exposure mode.
Again, 18% gray is used to create predictability so we can work with our camera’s TTL light meter and auto exposure modes. You always know how your camera is going to operate in each situation.
Sometimes its easiest when we distill things down to an if this than that bullet point list. So, here you go. . .
18% gray is still relevant and something you need to consider when:
You use auto-ISO, aperture priority, shutter priority / time value, or any other auto-exposure mode because your camera will always adjust it’s exposure to render the dominant tone of light (which can vary in a given situation depending on which metering mode you use) to be 18% gray. You then compensate for this by using your exposure compensation to add or subtract light based on how YOU want that tone to be adjusted from 18% gray.
You still set your exposure based on the TTL light meter within your viewfinder.
If there was one single governing truth to all aspects of photography, I think it is this: there are multiple ways of achieving the same outcome.
This applies to post-processing and field craft alike.
There are several ways to go about achieving a proper exposure. I would argue that some are needlessly more complicated now than others, but there is not a right or a wrong way to do this.
Me, I don’t use any form of auto-exposure. You won’t find me using aperture priority or auto-ISO or anything other than manual exposure. That’s not because I take some jaded and high-minded attitude to any of this. I just find it to be far simpler to achieve my goals in the field.
One of the biggest challenges today for just about every photographer who wants to get into or learn nature and wildlife photography is that the world is full of so-called gurus and experts. With countless blogs and websites and “courses” and YouTube channels and crazy people like myself publishing magazines, the internet is saturated in what is often contrary and opposing information. And all these alleged experts come with their own thoughts and perspectives and ways of doing things.
This is the joy of writing about and teaching photography today. Everyone is an expert. Everyone has their opinions.
Heck, if you have read my book Mastering Exposure: Rethinking the fundamentals of wildlife photography, then you know what I mean. In that book, I make the argument that exposure is made out to be way more complicated than it needs to be and it’s high time we get rid of the mental lent and minutiae like the exposure triangle, for instance. My philosophy here is completely different than 99.9% of photographers out there teaching wildlife photography. Does that mean that my way is the right way? Absolutely not. It’s a methodology that works for me and the way I see and think about wildlife photography – AND THAT’S ALL.
That’s why it’s important to understand that there are many ways to achieve the same goal.
This discussion of 18% gray is a good example of this. Photographers who picked up a camera and learned during the age of digital photography never talk about 18% gray. Many don’t even fully understand its implication on our photography. Does that mean their knowledge is subpar? No, not at all.
Photographers who have taught themselves the craft after the so-called digital revolution never had to learn about mid-tones in the field because they could just look at the photograph on the back of the camera and associated histogram then adjust from there.
On the other hand, those of us who learned the craft back in the days of film had to understand the concept of 18% gray, how to read a light meter, what metering modes meant and how they affected the way in which cameras were reading light, and what impact all of that would have on the photograph. Some photographers would find a mid-tone in the same light as their subject, spot meter on that spot, set the exposure, then recompose and shoot. The flank of an elk was a good mid-tone and made life easy for instance, unless you had intense highlights reflecting off snow.
Highlights could be a real issue with film since the dynamic range was so small. Slide film, which most magazines preferred to work with, had a dynamic range of 5 stops. Compare this to the 12-16 stops of light found in modern flagship mirrorless cameras. For this reason, scenarios like the example of elk in the snow led others to argue that with wildlife photography, instead of finding a mid-tone in the scene, we should spot meter off the brightest part of the composition and adjust our exposure for that alone – which was school of thought I come from.
These were two radically different ways of approaching exposure with film. And they translated to fundamentally different ways of thinking about exposure when digital technology came out.
Do you remember the argument that a proper exposure should look like a bell-curve on the histogram? You can trace those roots back to the obsession with 18% gray and exposing for mid-tones with film. A bell-curve means most of the information is centered around 18-gray and plays it safe with both shadows and highlights – exactly what so many professionals and amateurs alike did with film cameras.
So, what do we do with this 18% gray stuff? I have told you that the way in which our camera reads light and creates exposures is built around this concept. But then I have also suggested that this is an antiquated way of thinking about photography. . .
Actions
Don’t worry about 18% gray. With modern digital cameras, and especially now with mirrorless cameras that provide live histograms within the electronic viewfinders, the histogram is the end-all-be-all of your exposure.
The easiest way to reconcile the fact that there is still so much conflicting information across the internet about 18% gray is to understand that this was once paramount to achieving a proper exposure with film cameras. This is how so many photographers learned their craft. And so, this is one of the many ghosts in the machine. It’s information that’s no longer necessary to consider in the field.
Even though our light meters, and the auto-exposure settings of our cameras, are still built around the principles of 18% gray to create predictability, the advent of the histogram radically changed the way in which the vast majority of us think of exposure.
If you want to know more about exposure and how I think we make it all out to be way more complicated than it really is, check out my book Mastering Exposure: Rethinking the fundamentals of wildlife photography in your membership dashboard at PhotoWILD Magazine.
- Jared Lloyd