On occasion, I use the preset WB when I need a custom WB not in the D100's menu. I use a Kodak 18% grey card. I find it easiest to place the grey card on the ground and do the WB proceedure. Is this best, or should it be placed at the subject, facing back toward the camera, as it would be if using it for exposure? (I shoot landscapes, so placing it "at the subject" is a relative term, which seems to require an extra hand I don't have!) Interested in thoughts and discussion........if you have an opinion, please explain/back it up. Thanks.