If you dive down the rabbit hole of exposure or metering, you won’t get too far before you come across the term “middle gray.” It may also be referred to as “neutral gray,” “18% gray”, or “Zone V.”
Most simply defined, middle gray is the very center tone between absolute back and absolute white.
The light meter in your camera is a reflective meter (also known as a spot meter). It measures the light that reflects off of the subject, but it has one catch; It wants everything to be middle gray at perfect exposure. To understand how to use a reflective meter with total accuracy, you have to also understand what middle gray is and where to find it, even amid nothing but color. We’re going to show you how.
It may come as no surprise that I bring up the master of tone, Ansel Adams. Around 1939-40, he and portrait photographer, Fred Archer developed a method and technique for determining optimal exposure. They dubbed it The Zone System.
The Zone System consists of a full tonal scale, ranging from absolute black to absolute white. The scale is divided into 11 sections, each with its own tone and value. The value ranges from 0-X, (That's Roman Numeral, 10), with “Zone V(5)” in the very center, representing middle gray.
Each section also represents one stop of light. So, one stop brighter than Zone V would be Zone VI, and one stop closer to white.
Utilizing the system to find Zone V, or middle gray gives us photographers a standard to reference so that we can nail exposure every time, no matter the lighting conditions.
Check out the graph below that shows The Zone System, as well as how it relates to an in-camera meter.
So how does this apply to color and shooting in everyday scenarios?
Meters aren’t programmed to interpret color, only tonality. So middle gray could also be referred to as middle “tone.”
You can find this middle point everywhere you look. It’s like most anything else. The more you do it, and the more you practice, the easier it will become. Try to imagine that what you’re seeing is in black and white. Take a look at the image below.
And now take a look at where I found middle gray in the scene.
You can see that, in this lavender field, I was able to find middle gray tone on the lavender flowers themselves, in the grass, in the deepest blue of the sky, and on the shirt of the subject.
Common places to find the middle gray tone out in the wild are in lighter grass or foliage, pure reds, pure greens, deep sky blue, gray stone, weathered asphalt, lighter black skin, and tanned, white skin.
For practice in spotting middle gray, I would suggest going to your digital photo archive (or even just the most recent shoot that you’re still editing away on) and selecting a well-exposed image. Make that image black and white and see if you can spot the middle grays. You might even take it a step further and bring it into Photoshop to check it with the eye-dropper tool. Our eyes play tricks on us, so it can become quite the game and challenge. Take a look at the fun optical illusion below:
What about situations with super tricky lighting?
If you understand The Zone System, and how the tones work together, you don’t have to only look for Zone V. You can search for other tone zones as well and adjust for middle gray. In a situation where there is a lot of contrast, which would make it more difficult to find middle gray tones, you can rely on shadows.
If you can’t find middle gray (V) but you can find Zone II, which would be deep shadows with visible texture, middle gray is going to be about three stops of light higher. That means that when you meter on Zone II, it should be three stops below perfect exposure and that’s where you set it. As long as the light remains the same, you’ll be shooting with exposure precision, in middle gray.
Refer to the images below:
With a backlit subject, you have to be careful not to set your exposure from the light shining right at you, which would result in an underexposed image. In this case, instead of finding middle gray, I can easily find Zone II (very dark shadow with details). I find it here in the shadows of the trees, mountains, and even on the back of the subject.
Because I know that Zone II is three stops below Zone V, (perfect exposure), I can meter for that. With my spot meter on a Zone II area, I set my camera to expose three stops under in that area. This configuration of settings will give me the correct exposure of my subject.
You can use this same technique with any Zone that you can accurately pinpoint.
A straightforward solution to finding Zone V is to use an 18% gray card. A gray card is a standardized tone used in reflective/spot metering to obtain an accurate meter reading. It is the same tone that your camera and other reflective meters are programmed to aim for, so that tone metered at center will result in correct exposure for the scene. You can carry one of these around with you, but chances are, you won’t always have it, and understanding The Zone System enables you to find many different tones and gives you the formula for the perfectly exposed shot.
We would encourage you to save the photo of the graph and keep it on your phone for reference. Even better, consider printing it and keeping it in your camera bag!