If you haven't already, you should get the book "light: science & magic" by Hunter, Biver & Fuqua. It is quit enlightening (pun alert). It's a good book with a lot of info. My first copy got so dog eared that I had to buy another. Sometimes I forget what I know and have to go back and remind myself that I knew this or that but I use the trick of making the light source larger with fabric a lot.