Using a Gray Card for Photography: What is It & Do I Need One? by Jen Golay

Written by Jen Golay

Have you ever heard of a gray card? Do you know what they’re used for? Why and when? If you answered “no” to any of these questions, don’t worry! I’ve got you covered.

And even if you answered “yes” to any of those questions, come along anyway, and see if I have any new information for you up my sleeve. I’ll start with this one: There is a gray card on the moon!

What Is a Gray Card?

A gray card is just what you think it is: a card that is gray in color. Gray cards are used to help you get a consistent exposure in your images.

However, it is not just any gray color; it is 18% gray. You may have heard that number before in connection with light meters. Light meters, whether reflective or incident, will give you an exposure reading that attempts to match this number.

It is called 18% gray because this particular shade of gray reflects 18% of the light that falls on it. But if you look at a scale that goes from pure black to pure white, 18% gray lands smack in the middle. (Eighteen percent gray is also known as “middle gray.”)

If you’re familiar with the Zone System, 18% gray is Zone V.

Find a gray card on Amazon.

Know that all gray cards are not created equal. Be sure you get a gray card that is meant for photography. They aren’t expensive. I have one in every camera bag I have.

If you don’t have one or forgot to bring it, there are some various hacks that can help in a pinch—some better than others. I would not recommend going to the paint store and grabbing a bunch of gray paint samples, as I saw suggested somewhere on social media. I’ll talk about some more reliable options a little later on.

You can see a few of my gray cards in the image below. All of them are smaller than a postcard when folded.

My favorite is the largest one that twists up into the smaller zipper pouch. The one that looks the worse for wear is the first gray card I ever had or used. It was a tear-away bonus from a photography book. The three cards have a clip on/off lanyard that you can wear around your neck so you don’t lose your gray card during a portrait session (like I have).

You might have noticed that some gray cards come with a black and a white section or additional black and white cards. If you’re wondering why those are included, they are also useful to film and digital photographers.

These cards can be included in the initial gray card photograph at the beginning of a session as references used to make measurements to aid in control development and exposure. The gray card became the standard for color balance in color negative film, color slides, and color prints.

The History of Gray Cards

Some history: During the 1930s, two gentlemen from the Kodak Laboratory learned that on average, a usual sunlit scene integrated to a reflectance of around 18%. This is also about the same time that light meters were available to photographers.

Kodak suggested using a Kodak film box as the first gray card since the box reflected about 18% of ambient light. They told photographers to measure the reflected light from the box and use that measurement to set their exposure.

During the 1940s, Ansel Adams and Fred Archer put out their method of exposure called the Zone System that offered a way for photographers to be more precise with their exposures. This system focused on Zone V, which was also 18% gray, and this became the standard for a balanced exposure. Kodak began including a gray card in their film data books.

When to Use a Gray Card

A gray card is a simple, easy, and inexpensive way to get precise exposures most of the time. You can use one if your camera has a built-in light meter instead of a hand-held incident light meter.

You can use one when trying to balance out the exposure in a high contrast scene. But remember that you may want to choose to expose for the highlights or shadows for artistic reasons.

You can use one when photographing something or someone that is heavily backlit.

You can use one when there is a light source in front of your camera or in the frame.

You can use one controlled shooting environments—like portraits, product, or food photography for beautifully exposed images.

You can use one when shooting slide film or black and white film—both of which have less latitude than color negative film—to have an exact exposure.

Depending on the type and age of your film camera, its light meter may not be as advanced as more recent cameras. Or it may be a rather primitive light meter.

For example, the light meter in my Nikon FM camera consists of three red dots. When the middle one is the only one lit, the exposure is correct. If the left or right dots is the only one lit, that means the exposure is either under- or over-exposed. If the middle and one of the left or right dots are lit that means that the exposure is only slightly (?!) under- or over-exposed. It’s definitely not very precise. And as you might expect, a scene with bright highlights and dark shadows makes it throw up its hands in despair. This is the perfect camera with which to use a gray card!

Even more recent cameras like the Nikon F6 have meters that can be tricked. Remember the meter in your camera wants to make everything it sees 18% gray. So, your meter would look at a black cat in a coal bin and think this scene is too dark, and it would tell you that your exposure needs more light, making the cat and the coal washed out and over-exposed.

Conversely, when your meter sees a white cat on snow, it will think that it’s too bright and tell you that your exposure needs less light, making the cat and the snow look a shabby gray.

What about mixing it up: a white cat in a coal bin and a black cat on snow? You’ll still have the same problem because the meter will try to compensate for one or the other—either over-exposing the coal or under-exposing the snow.

Using a gray card will get your blacks black and your whites white in any of these situations.

If you’ve ever been in the digital world, you know how important it is to not blow out your highlights and may have been told to expose for the highlights and bring up the shadows in post. This is pretty similar to shooting slide film.

There is almost no latitude in slide film, and over- or under-exposure will cause muddy images and unpleasant color shifts. I almost always use a gray card when shooting slide film to make sure I get a good exposure.

Black and white film photographers work under the adage to expose for the shadows and develop for the highlights. That’s because there isn’t much you can do if your shadows are under-exposed on black and white film—not in development, the darkroom, or the film scanner.

Black and white film photographers know how important it is to have enough information on the negative in the shadows. A gray card will help make sure you do.

Other Uses for a Gray Card

If you come from the digital world, you might be familiar with a gray card being used to set a custom white balance. There is a feature on most digital cameras that permits you to create a custom white balance, which is a simple and great tool to have if you’re working in light that might turn your subject’s skin green.

In film photography, your white balance is determined by the film that you use. Most film is daylight balanced, but there are other films that are tungsten balanced like CineStill.

Gray cards were also very important as a point of reference when making color photographic prints. A photographer would take a photo of the gray card in the same light as the images that followed it, and after processing the film (which when done by hand can vary slightly in developer temperature or time causing a change in density or a color shift) use a densitometer to set or change the printing settings. This is basically what the eyedropper in Photoshop or Lightroom does.

How to Use a Gray Card

Using a gray card is quite simple and can be done in many any photographic situations. Unless you are making prints, you’ll probably only use one to get an accurate exposure. If you don’t have a hand-held light meter (incident or spot), using a gray card is an easy and inexpensive substitute.

To use a gray card, place it in the same light as the subject you want to photograph. If it’s a portrait, have your subject hold it for you. If it’s a landscape, just make sure that the light on the gray card matches whatever you want to meter. This can be full sun or shade. You don’t have to put the card directly in front of the subject—just in the same light.

If your camera has a spot meter, be sure to switch to using it. Find your gray card in your viewfinder making sure it fills at least 15% of the frame.

If you can do more, you should. The less the camera sees that is not 18% gray the more accurate your exposure will be. You may need to tilt or reposition the card so that it is receiving the same light intensity and color as the subject.

Look at the meter scale. Dial in an exposure that zeros out the meter, that makes the marker land solidly in the middle of the scale. Move the gray card aside, and without re-metering or changing the exposure that you have dialed in, make your exposure.

If your camera doesn’t have a spot meter, no problem, you’ll just need to get up close to the gray card and make sure it fills the frame as you dial in the correct exposure.

If you’re using an older camera or one that does not have a built-in reflective light meter, you won’t find a gray card very useful without a hand-held spot meter like a Pentax Digital Spot Meter.

Not all photographers are able to use a gray card as an inexpensive light meter. As you’ve probably noticed in my examples, using a gray card to meter requires a mostly stationary subject. Using a gray card would not work well for sports photographers, street photographers, wildlife photographers, or parents-of-young-children photographers.

Gray Card Alternatives

If you’ve forgotten your gray card or want to go test out this idea right away, there are a couple of hacks that work in a pinch. These aren’t as accurate as an actual gray card, but they will get you pretty close.

You can use a blue sky or green grass as your gray card. The color is not important, it is the amount of light reflected by these two things that match the gray card.

You can also use the palm of your hand as a makeshift gray card no matter what color your skin is. But you will have to adjust your exposure by 2/3 of a stop from what your camera meter tells you.

If you want to be a little more accurate with the hand gray card, “calibrate” your hand by metering your gray card in good, soft light and then metering your hand in the exact same light. Note the difference and be sure to adjust your exposure accordingly when using your hand as your gray card.

Final Thoughts

Gray cards have been around in film photography for a long time. And while some reasons for using them have changed, others have stayed constant. They are a simple and inexpensive way to make precise exposures when faced with a high contrast scene or when using film with a narrow latitude.

And while there are some hacks you can use instead of a gray card, I think you’ll find that it’s just easier and more accurate to always have one stashed in your camera bag.

Have you ever used a gray card? Or do you think a gray card might be helpful to you?

Thank you so much, Jen! Jen is a regular contributor here at Shoot It With Film, and you can check out her other articles here, including How to Control Contrast in Your Photography and How to Balance High Contrast Lighting Situations in Photography.

You can also check out more of Jen’s work on Instagram.

Leave your questions about using a gray card below in the comments, and you can pick one up for yourself on Amazon here.

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Jen Golay

Jen Golay is a senior portrait and travel film photographer and a regular contributor for Shoot It With Film. Find her other articles here, such as How To Shoot Kodak Gold 200 and Olympus Pen F Half-Frame Film Camera Review.

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