I was wondering if anyone knows of a color chart that is 4'' by 6''. The reason I ask, is that I would like to get something that I could just attach to the back of my slate, which happens to be 4''x6'' without clappers. That way I could have all my info on the front, and just turn it around to have my color chart. If there isn't one that would fit, is it possible to print one with enough accuracy to be useful? I doubt the latter is possible, but I was just wondering. Also, how do you use a grey scale to adjust exposure? That would be helpful to have on there was well. Input would be greatly appreciated!