[RSStory]

I also use and highly reccomend the calibration target from photovision. It is a great tool to have. When I shoot wedding if I dont have time to shoot the target prior to the shots then I just take one after the fact with the target in it and can then use that for white balancing later. As Roger said, it is ideal to fill the frame with the target, but in a pinch you can just shoot the target in the scene and then in post just crop in on the target. While this isnt ideal it can be better then nothing. You then just crop in on the target in your raw conversion to and make your adjustments and apply them to the rest of the shots. You do have to be a little more careful this way especially if the light isnt the same.

At any rate, this is a tool that is worth every penny.

Scott