Originally Posted by ARTFORMS
I tried setting the white balance on my Canon and used a white card to
set the white balance. I put the white card in the same light as the subject
and shot a picture of it as instructed in the manual. Shot the card using
auto balance and then went to the custom balance on the camera settings.
I have been told that a gray card also works.
You can use gray or white card (the card should actually be white). Here are two photos that show CWB on a Canon 20D using a white card for one and gray card for another:
The first show is with a white card, and the second with the gray card.
Keep in mind that you need be close enough to the card so that the center circle in the viewfinder totally covers the card. I usually find you get best results when you fill the whole frame with the card (whole viewfinder).
With the 20D you must remember two points after taking the reference shot. One is to pick that show in the Menu for Custom White Balance, and then be sure to change the Camera to the CWB setting using the upper LCD.