How to use the gray card for photography? What are the camera settings when shooting a gray card (D300S)?

First, set the camera white balance to custom white balance. Nikon is not sure. Take Canon as an example, shoot a gray card with a custom white balance, then play back the photo, make custom settings, and then your white balance color will be accurate.

Gray cards are rarely used now, if not under certain circumstances. Because the white balance can be adjusted in the later stage of ps, generally speaking, no one uses such a stupid method, because the light will change frequently, unless you shoot in the shed. If not, you can adjust the white balance in ps and have whatever hue you want. Why do you take a gray card?