I use to think that perfect white balance was the way of the "pros" and that I needed expensive equipment or hassle with grey cards to achieve such great quality. Oh, how I have been wrong. My friend, Ken Ockler, let me borrow this spiffy device called the Expo Disc when I travelled to Yellowstone. He instructed me as to how to use it and told me it would make a HUGE difference to my results. At first I was a bit skeptical but I tried it anyway. This little disk was a god send!!! It works miracles with your image results! Sadly I had to return it to him, but this shall be my next photography purchase, and should be anyone else's as well if you don't already have it! I cannot rant and rave enough about this plastic miracle disc. Check them out! They are also fairly inexpensive.