The 18% Gray Card has several uses. It can be used to determine the correct exposure (hence the 18% bit) and can also be used in a couple of different ways to help set up the correct color balance for the shot
Exposure
Taking a light reading from an 18% gray card guarantees you a correct exposure, provided that your main subject is lit at the same level. Get your subject to hold the card and zoom in so that the card fills the frame. To get the best result, you need to set the exposure manually.
Color Balance
One way to get the color balance set correctly is to take a picture of the card, making sure that you fill the frame as much as possible with the card, and then store the
Keep the picture you shoot and you can use it in a different way in the computer. Read the rest of this entry »