The gray card is used to render correct exposure by:

The gray card is used to render correct exposure by:

• A. A card with a color of halfway between black and white, often called 18% grey. It is what your meter will "see"
• B. A card that calibrates white balance
• C. A card used to block sunlight
• D. A card used to record scales

Answer: (A)

A gray card provides a known midtone reference for exposure. Camera meters are designed to treat a scene’s middle gray as about 18% reflectance, so when you meter off the card, the meter can determine the exposure that will render that midtone correctly in the final image. Using this known reflectance helps ensure overall scene tonality stays balanced, avoiding overexposure of bright areas or underexposure of shadows. The card isn’t primarily about white balance, which uses a color reference to set color temperature. It also isn’t used to block sunlight or to record scales; those serve different purposes in lighting control and documentation, respectively.

A gray card provides a known midtone reference for exposure. Camera meters are designed to treat a scene’s middle gray as about 18% reflectance, so when you meter off the card, the meter can determine the exposure that will render that midtone correctly in the final image. Using this known reflectance helps ensure overall scene tonality stays balanced, avoiding overexposure of bright areas or underexposure of shadows.

The card isn’t primarily about white balance, which uses a color reference to set color temperature. It also isn’t used to block sunlight or to record scales; those serve different purposes in lighting control and documentation, respectively.