Hi! I have 3 set-ups in a greenscreen stage: - 3 girls walk on water (on 3m x 6m pool); - walk on a wall of skyscraper (on 4m x 10m piece of mirror wall); - stand on the roof of skyscraper. All of this must be wide-shots shooting in different angles and movement of a crane. This shots will be combine with shots of real river, real skyscraper and high angle view of the city. I need some advice with greenscreen and day effects simulation. In a stage I have to simulate overcast and sunny day. What is the best natural and simple way to simulate an overcast day: spacelights or big batterfly frames (or maybe something else)? 1) in the case of spacelights: a] is there any formula to calculate how many fixtures I have to hang by set area? b] any formula to calculate an exposure with spacelights? c] I want to add a little cool quality to a sunny day. Is it real to cover all (or half) spacelights in 1/2 CTB? Is it common way? 2) in the case of butterfly frames: a] how much area of frames will I have to have (taking into account the set area)? b] will it be more naturalistic either light through frames (silk, etc...) or light in reflection? 3) I have several reflection surfaces in a set: mirror floor (4m x 10m) and waterpool (3m x 6m) and I have to shoot this set-ups in many angles. Are there any advices about working with such kind of surfaces and greenscreen/lighting approach etc. 4) can I use some lens diffusion with greenscreen? Thanks for answers!