Appendix A: How to Use the Gray Card and Color Checker
Perfect and consistent color doesn’t happen by accident. Knowing how to use your included gray card and color checker could save you a lot of postproduction hassle. While they aren’t tools I would often use at a wedding, they are a must-have for studio or product photography.
The Gray Card
The color temperature of light varies and is dependent on the source from which it comes. You may even see variances in color temperature from the same light source, such as a speedlight or studio strobe, when the power settings are changed. Color temperature changes can also occur as the light source ages or, in the case of the sun, as it moves across the sky. Although you may believe that you have a neutral item in your scene from which you can select a custom white balance ( ), the best way to know for sure is to use a gray card. A gray card is designed to reflect the color spectrum neutrally, providing a standard (or baseline) from which you can measure white balance in other images taken within the same scene and with the same light source. By taking a test shot that includes the gray card, you guarantee that you have a neutral item against which you can adjust colors later if you need to. Make sure that you place the gray card in the same light as the subject for the first photo, and then remove it and continue shooting.