I used to be an expert at using color-correction filters to prevent or remove color casts in film slides and prints. I'd place them in front of the lens or flash to balance tungsten or mixed lighting sources. Then I'd use a set in the darkroom when making color prints. Now, white balance systems built into digital cameras and image-editing software threaten to neutralize my filter mastery.
But WB systems even on expensive DSLRs can be fooled, forcing you to fix the color in the digital darkroom or printing kiosk. Why waste time after shooting when you can do it right in the camera? Here's how to keep your WB from being fooled: