Below is a message someone here wrote about setting the Custom White Balance that I saved.
Disclaimer: I did not write this explanations.
I can tell you how it works on the 20d, other models in the same line should be similar or identical.
First, take a picture in the light you will be shooting in of the backdrop you are shooting (if it's clean white) or a white card if it's some other color. I have to set my lens to MF for this as the lens will not be able to lock onto it. Some might say an 18% gray card would work for this or any other color that was neutrally balanced (between RGB) whether dark or light. I can't say whether they would or not, I just use white.
Second, go into your menu and select the option "Custom WB" and activate it. The menu will tell you to select a source picture for it to reference to determine what true white is. Select for the source picture the picture you just took. By default on mine it is always the pic being displayed on the screen.
Third (or first if you were prepared for this and did it right off) set your White Balance setting to the Custom WB icon. The camera menu will show you a replica of this icon in the Custom WB menu from the second step, but it basically looks like two wedge shaped triangles placed on the long sides with the points facing each other forming something like a exaggerated wide flat V shape. Hovering above the center of the V is a small flat oval or rounded square. On my white balance menu on the top of the camera it's the 3rd option down in the left hand column.
Once you have this set in the menu correctly... all of the pictures that follow it will use the setting you provide to the camera until you change out of that mode back to a different type of WB. I try to do the step 3 first because when the White Balance selector is already set to Custom WB the menu will not remind you to set it there, thereby confirming that it's already done and that your Custom WB will take effect. I thought it was easier to explain it in the order I did to contrast the steps.
A custom white balance will not be a perfect help if you are using mixed temperature lighting from what I've seen. With different color lights I've had one side of the picture be correct white and the other take on a different tinge of color. It's good to be sure that your light temperature ratings are the same for the best results.
i got a quick question about Custom WB. How do you go about setting it?
I took a picture of my studio with not product just the white background and went to CWB setting. Now how do i select the WB i want to use as the Custom?
thanks in advance
