How to use 18% grayscale card?

The gray card is used to customize the white balance.

The specific operation is as follows:

The camera enter a user-defined white balance interface,

Then aim at the gray surface or white surface of the gray card and take photos. If autofocus cannot be completed, you can put a small object on the card surface to complete focusing and take pictures.

At this point, the camera will prompt you whether you want to use the white balance of the image as a custom white balance, and just select "OK".