Just to follow up on the gray card issue that came up in one of these threads a little while ago.....
I had been using the PhotoVision Digital Calibration Target and loved it...but it came up that the gray portion of that card may not be neutral enough to get a really good color balance. Someone "important" in ILP mentioned the RMI Digital Gray Card was the perfect color to use for white balance. It was fairly inexpensive, so I decided to try it out.
Well, I did discover that my white balance was much more accurate when using the RMI card than with the Photovision target. BUT...I missed the ease of checking exposure using the Photovision target. SO...what I did was:
I added some little velcro dots to the back of my RMI card and on the gray section of my photovision target...and now I have the best of both worlds! It's perfect! I get spot on exposure and spot on white balance.