To get the best from your digital camera, using a gray card is the most accurate method available for setting white balance. WhiBal's G7 White Balance Reference Gray Card (7.5x10") is extremely accurate, convenient gray card that can be used in any shooting situation. It can also be used to set neutral White and Black reference areas for setting dynamic range in digital capture using the Black and White Eyedroppers available within Lightroom and other RAW conversion software, Photoshop and most other editing software.
By photographing a gray card reference for each lighting situation, you'll be able to achieve a proper white balance for all of your pictures. The gray card reference picture can be used with software to balance the color casts that various lighting conditions produce with all digital cameras.