Extremely bright light
I have a client that wants to use a shot in an upcoming commercial where the actors open a door and all that is seen is a bright wall of light. I'm curious to know, how would I accomplish this? What kinds of lights would I use, how powerful would they have to be, where should they be positioned, etc?
Probably could be accomplished fairly easily...
If you want to do it practically on location.... I would try hanging a silk or other diffusion material outside the door (if not a cloth rag, maybe a roll of Lee 250 or something along those lines).
Then from the outside simply blast the diffuser with as big an instrument that you can get your hands on. Something in the 1200w HMI range would probably be more than sufficient. If you design your interior lighting with levels that are on the lowish side (but still sufficient for your camera without jacking up the gain) you will have an easier time blowing out the door lighting. Alternately, if you don't want to light through the diffuser, then put a white background at a bit greater distance behind the door (could be a white solid rag in a frame, or just a roll of white seamless background paper from the photo shop). Then front light that with similar instruments. A 1200w HMI (or maybe even an 800w Joker-Bug) would probably be enough.
If you want to do it in post, hang a well evenly-lit greenscreen outside the door. In post, replace the green (or blue, if you prefer bluescreen) with pure (or near) white. Also use the chromakey shot to create a matte to add some "glow" around the edges (could be as simple as adding a blur filter to the matte).
Either will work well, but give different results. If you go the practical route, the opening door will also illuminate the interior scene as the door opens. If you go the post route, it will not (unless you were to ramp up the brightness of the shot as the door opens).
Just depends on the look you are going for....
Fantastic Plastic Entertainment, Inc.
I'd recommend using a diffusion fogger in the space to enhance the glow of the wall of light.
October is the perfect time to pick up a cheap Halloween fog machine and fluid at many local stores, this will really help the effect you're trying to do, especially if the fog wafts in from the light side of the door.
You can use white foam core somewhat larger than the door frame as a "white mirror" reflective source (smaller panels gaffer taped together will do), angle that about 45 degrees to the door and hit that with some 1k totas from just inside the next room/ opposite side of the set wall. Or make a wood or PVC frame or using a butterfly frame if you have them, hang an translucent white diffusion material on that and as has been said, pour on the lights from behind it.
Diffusion for this effect could be something like a plain white shower curtain from the dollar store or white gift wrapping tissue, but warning: those things are not heat-proof so be careful not to melt or ignite it with light palced too close. In this use, you want the lights farther back anyway, to maximize the coverage and eliminate hot spots. Otherwise, yeah, a Rosco or similar tough Opal frost is what I'd try first, in the frame and hit from behind.
You can do a little ramping up of the iris to help blow things out, and finish it off in post, but I'd be careful with the manual iris settings so as not to throw off theparts of the shot we want to keep, and to match the shot before the door opens.