blue screen help

[Andy Fortenbacher]

I am currently in preproduction for a short 16mm film. We are looking at doing several scenes with the aid of blue screen. I am looking for advice on two particular things. First, when using blue screen outside, what is the best way to light the screen? Should we use diffused (artificial) light , or just use let the sun do all of the work? We also have a scene where we will be suspending someone from a harness (for a falling sequence.) The blue screen will be hung above the suspension riging. This image will be added to a night exterior scene, where a person has fallen out of an apartement complex window. My concern is lighting the person so it looks realistic as they fall . Should I have them fall through a pool of light (resembling the ambient light from street light,) while having the rest of the vertical fall darker? Or should I have them lit evenly the entire way? How bright should we light the blue screen for that shot? Any help would be greatly appreciated! Thanks. -Andy