Gray card . . . 18% . . .?

A Gray Card is exactly as it sounds: A card that is gray. More specifically, a gray card is generally middle gray, or 18% gray. They tend to be small, portable, light, and easy to whip out of a camera bag when necessary.

Remember a gray card is middle gray, also known as 18% gray. This number is important because 18% is what your camera’s meter is trying to calculate when it determines a correct exposure for a scene. If you put a gray card in front of your subject and take a meter reading, you will get a balanced exposure regardless of any tonal contrast in the scene.

Now, you might be wondering: What about my camera’s meter? Why can’t I rely on it for a good exposure?

Camera meters are very, very good, but they make mistakes, especially when faced with significant tonal contrast, as well as scenes that are naturally very light or very dark.