Hi, I found an incredible TurboCAD newsletter the other day. This is their subscribe page [URL="http://www.cadcourse.com/CCCSubscribe01.asp"]www.cadcourse.com/CCCSubscribe01.asp[/URL]. They have an article on lights, categories & luminance in a back issue I found interesting (complete with movie). And other useful tips & tricks. All the best, Geoff.