I need to buy some silk (etc.) for a 12 x 12 overhead butterfly, and I was thinking about "1/4 stop" (which is really .6 stop) white imitation silk. The purpose, of course, is to reduce contrast in the sun. My thinking is this: I don't want to knock the light down too much, just diffuse it a little, so that whatever is in the background will be at about the same exposure as my subjects. Does this make sense? What am I missing? Thanks for your help.