White Balance...

Okay, White Balancing on a DSLR. Any takers?

I wanted to find out how to use and how the Custom White Balance on my EOS 400D works. Anybody use it?

The manual says take a picture of something white and then run it through the custom white balance menu. Is it just take the picture in any old AutoMode of a white surface.

Obviously this wasn't the white surface I used but I upon furthar inspection, the area of it slightly higher up without the logo wasn't exactly white.

My understanding is that you take the picture, your telling the camera that this is meant to be white even thought the light falling upon it makes it slightly orange. The camera then says that's okay TFP, I see that tint so I'm going to even it off by doing a few tricks you can't see and make it look more white.

Is that how it does it?