NCFOM (9 replies and 6 comments)
Roger i am wondering about this lighting diagram?
There is no diagram for that coffee shop as it was a pretty simple set up. I had two large diffusions outside the window and something like 3 x 12K HMIs directed through it. The only tricky thing was turning around to shoot the reverse towards the windows, which we did secondly because we started shooting early in the morning before there was much daylight. Or maybe it was the other way around and we started late in the day and then continued as the light had gone. It was a long time ago!
3x12k HMIs only give large wrap source like sun light?
On a shot like this, if you had unlimited space outside (large parking lot and no need to cut overhead sun for example). How do you normally determine the distance (from subject) that you would place your diffusion outside? Are you quite particular about about how you want the light to fall off into the background and set the distance accordingly? Would you use the photometric charts for the lamps and say that you would like the background to be X stops under and set the distance accordingly?
Very much appreciated
I always do that by instinct, I guess. I never refer to a photometric chart in a case like this. I rarely use one at all, except, maybe, for large night exteriors. The physical space often dictates where you can put your lights. Here I could only put them as far back as the parking lane outside the windows. I imagine I had the lamps quite high to be able to more easily cut the light from the back wall using duvetyne hung above the frame. A light grid diffusion would have been on frames outside the window and there was probably a second layer of diffusion taped on the window itself. This second layer might be a very light diffusion, such as an opal, or quite heavy, such as a 216. This and the distances involved controls that quality of the light to some degree.
Thank you very much!
How much distance approximately could allowed you controls the quality of the light some degree.
Roger, would you have had cuts either side of frame also? Thank you.
The further the light from the space, which was in this case the Coffee Shop, then the more even the light is in depth. If you want something close to the window to be that much brighter than deep into the space you have your light source close to the window. Take direct sunlight, for instance. The light from the sun where it hits an object close to the window frame is exactly as bright as when it hits something further in the room but the light from a lamp a few feet from the window will fall off very rapidly.
Do you have to learn these things or do they come by training the eye and looking at how light affects different environments ? Because a lot of what you say about sunlight and light in general comes to my head as nature, I know these things without actually having to learn them, I know how sunlight looks compared to artificial sunlight, can I use that instinct on set? is it safe to depend on how you remember how things look or do I have to study every light source and how it affects the scene? Lighting is a very complicated matter to someone starting and a lot of why it got complicated is that people don't trust their eyes enough to notice if something looks bad or wrong, please correct me if I'm wrong!
To try and understand light fall-off better, I did a few calculations using this scene from NCFOM. I'd love to know from Roger or the forum members if I've thought this out correctly. Here goes... Using the reverse shot(posted below) I estimated the distance from Tommy(assuming he's in the same spot for both shots) to the front window is about 25'. I'm guessing that the 12K HMI's are about 5' from the window. That makes 30' from Tommy to the lights. Using inverse square, the intensity of light falling on Tommy can be represented by 1/900. From the photo, I estimate the distance from Tommy to the back wall is about 20'. So the intensity of light falling on the back wall should be 50'(30+20)X50=1/2500. The difference between Tommy and the back wall then, is a factor of 2.77. So the back wall would be about 2.8 stops under as compared to Tommy. Then Roger hung duvetyne above frame, knocking the light down further still. Looking at the man with the baseball cap in the background past Tommy's news paper, he looks to my untrained eye about 3-4 stops under Tommy. Is that right? Did I think that through correctly? Would love to know. Thanks.
If I give myself a try at a guessing game, I don't think the 12Ks would be that close to the windows. As apart from the intensity, the fall off would be very fast being that close and since the intent is to emulate the sun, the farther the source, the more even the lighting over distance. Also, Roger mentioned having possibly two layers of diffusion. HMI have to be at a minimum distance from a diffusing material so it does not burn...The guy with the cap is just becoming a silhouette. So yeah he should fall 3 to 4 stops under exposed. But for me nothing can replace trying things out with one light, a tape measurer and a light meter...
I wonder if it would be more correct to use the 2nd layer of diffusion as the light source in these calculations - as you would for a bounced source?
The lamps were definitely in the parking lane so that would make their distance from the window about 15'.
The diffusion has to be allowed for as the source of the light. Perhaps not exclusively but a double diffusion would make the lamp itself less relevant to the inverse square law calculation. Of course, the diffusion on the window is not the source either as that is lighter than the grid on the frame behind it. Too many calculations! I would suggest you take a lamp and look at the options.
Roger how did you judge it must be 3x12k HMI to light that coffee shop. For instance in this case if production can't afford you 3x12k lights what's your alternative idea to get the same quality of the light.
Ha! Yes that would be easier. I was just enjoying working it out mathematically. I've actually learned a lot. By the way - the lamps being 15' from the window obviously decreases the difference in the exposure reading between Tommy and the back wall. Which makes sense - as you felt it needed the extra cut with the duvetyne.