HMI Spacing for Night Exteriors (8 replies and 6 comments)
I hope you’re doing great.
I’ve been wondering about your night exteriors where you have to light large areas like in “True Grit” (Greaser Bob Scene) or “No Country for Old Men” (The Basin at Night) and I would like to ask a question regarding that.
When you use many large HMIs for the soft moon light effect as in “True Grit”, how do you determine the spacing between the units to still make it feel like one large source while avoiding (noticeable) multiple shadows? I understand you regularly use the "many lightbulbs for one source approach", but with the HMIs in those night exteriors being so far away, aren’t they still a relatively small source even if combined?
I understand we want the HMIs to be far away from the talent to have an even falloff across the set, but I’m not sure how I would determine the distance between the actual units.
Thank you very much and be safe
Keep in mind that there are always cost and logistical issues... you might want a light every three feet for example to look continuous but if you needed a line 60’ long to cover the depth you need into the background, that’s 20 lights — 20 lights to set-up, cable to a generator, etc. A line producer might get sticker shock in terms of rental and extra manpower and then you’ll be trying to make it work with 12 lights every five feet!
If you did put a light every 5 feet instead of 3 for it to not create several shadows and/or to give it a smoother look do you add a thin layer of diffusion to kind of 'merge' them?
I forgot to add that if you try doing it with fewer lamps spread further apart, of course your total output would be lower.
Our producer on 'True Grit' did get 'sticker shock' but he got over it when I explained how much more quickly I could work at night if I had everything I might need rigged and ready to turn on at the flick of a switch.
If I use a 4' wooden batten strip I might rig it with 6 household bulbs spaced approximately 9" apart. Or I might use 9 bulbs equally spaced at about 6" apart. The closer I use this 'unit' to a subject the more I will be aware of multiple shadows. The multiple shadows will always be present, unless the unit is very far away, but I can get closer with the 9 bulb version that the 6 bulb version before that becomes a problem. It is the same principle with a row of individual HMI lamps spaced at 7' intervals. You can simply draw a diagram to see the how a 60' row of, for instance, 25 single sources will appear when it is 700' from a subject relative to a 4' row of 8 single sources that is 9' from a subject.
On 'True Grit' it was not a case of wanting to be far away from the subject to make the fall off even across the set. Of course, fall off needed to be taken into account but the positioning of the lamps was driven by the choice of location and the width of the shots we had planned.
On 'No Country for Old Men' we had a natural position for our lighting, which was on a high bluff overlooking the action. The bluff was a feature that drove the choice of location and a key element in the daylight scene that introduces the setting. I wanted a sharp 'moonlight' look to the night work so, in that situation, I only had to choose the kind of light that would be powerful enough to give me an exposure from that bluff. I had used a Musco in the Badlands of Dakota, whilst filming night work on a film called 'Thunderheart', so I felt confident that two units would be enough, though only just enough, for my needs. 2 x 96 K but I still shot much of the sequence wide open.
For 'True Grit' I wanted a softer feeling. At one point it starts to snow. A hard source would not have felt right to me without the justification of a moon. We were shooting a multitude of angles in a very short period of time so I also wanted something a little more 'forgiving' for my close work. So, the rig was designed to far enough away to be out of our widest shots, above frame on most of our coverage and, even at that distance, somewhat soft. When I held up the palm of my hand on the set I could see every shadow from every lamp even with some soft diffusion on each of them. But, bear in mind, multiple shadows are hard to see across the curves of a face especially when there is some movement. Diffusion, when on the front of a lamp, will not help unless you are very close to it. Diffusion on a lamp spreads the beam but it does not mitigate the shadow. At any distance at all, the source is, in effect, still the same size although the beam is spread more evenly. A diffusion has to be far away from a lamp to have any affect on the sharpness of a shadow. When the lamp itself is over 700' from a subject, I suspect, that diffusion might need to be over 20' from the lamp before any difference would be noticed, which, if you study beam width on a photometric chart, would require a pretty big diffusion.
We are doing great, thanks. Frustrating for us all. Stay safe.
Dear roger 60' row of, for instance, 25 single sources will appear when it is 700' from a subject relative to a 4' row of 8 single sources that is 9' from a subject. Both distance would give same degree of softness? You mentioned if you study beam width on photometric chart, it would require a pretty big diffusion!. What is the relationship physics science relationship between diffusion and beam width? Die you mean it pretty big diffusion for one single 18k HMI or 25 lamps? Stay safe!
When you place diffusion on the gel frame directly on a lamp it makes no difference to the size of the source and therefore not difference to the 'softness' of that light source. The sharpness of the shadow stays the same even if the beam width is enlarged. To make a source softer you need to make it larger. That is why the sun would light something really softly if you were a few thousand feet above it. So, to make the light coming from an 18K HMI lamp that is 700' from a subject 'softer' you would need a pretty large diffusion frame and fill it with the beam of the HMI. But think about it. A 12' x 12' light source at 690' would still look pretty small. That is why I needed a 60' or 120' row of lights to create a source that was anything like 'soft' at that distance.
Thank you for the detailed answer! I wanted to finish watching your Collider interview from a few days ago first before saying anything else… Thanks for making two hours of Corona time so enjoyable!
Two things came up in that interview that I would love to follow up on a bit.
You and James mentioned one of the benefits of shooting digital was the ability to show the image to the director and double-check for example that they really meant “silhouette” when you told them it would be in silhouette. Have there been instances where you found it restricting that so many people would now be able to see the image? Perhaps the director wouldn’t be scared to go very dark on a shot, but then a producer saw it or the talent and they might urge you to go a bit more “conservative”? There are several interviews where you mention silhouettes and the vagueness of what a director might mean when they agree for it to be “dark.” I imagine seeing a shot like the very dark beginning of the marvellous train sequence in “Assassination” on the monitor on set might make some directors a little nervous.
My second question is in regards to your collaboration with 2nd units (or otherwise “special” units). You mention you like shooting things single camera as much as possible, but occasionally having multiple units may not be avoidable. I am curious, how do I have to picture the collaboration between you and let’s say the DP of the miniature unit on “Blade Runner 2049”?
Thanks again for taking the time and all the best!
I have been lucky, I guess, because I have never had a problem with a producer, that is not in the way you suggest. Years ago, when I was shooting a film in Kenya and miles from anywhere, I had to answer a call from a producer who thought my dailies were too yellow. I had only seen those same dailies on a VHS but they looked fine to me and my timer thought so as well. I asked the studio head where he had watched them and he said he was in his car, driving along the Pacific Coast Highway! I rang off.
Denis and I were watching everything the 'miniature unit' shot on 'BR2049' and we talked with them every day. In that case, what was shot only served as a reference for some complex CG imaging.
With any second unit you have to be very clear what you need. There is little more frustrating than watching miles and miles of excellent second unit footage that doesn't include the one image that you really need for the cut. I always say - shoot what you want but shoot what we ask for first.
I must be a bit thick but driving along the Pacific Coast Highway, why would the dailies appear to turn yellow. I guess we are talking about “White Mischief”. Can’t think of a VHS player that would run in a car. Betamax maybe but that is 110 volts.
The film was 'Mountains of the Moon'. The point being, who in their right mind would judge dailies in that way. There were just very low grade playback systems that you could use in a car in 1989.
I see what you mean, rather disrespectful imo. many thanks.
Wait, so none of the miniature shots from 'BR2049' actually appear in the film? When I watched this BTS video (https://www.youtube.com/watch?time_continue=26&v=sLxxbfsj8IM&feature=emb_logo») I imagined they might use these shots as VFX plates to build from and add CG to them rather than recreating the shots with CG from scratch?
Stupid question, but since you already had pre-vis shots to help with the miniature work, why would you need the miniature shots at all if the final shots will be completely CG anyway? Is it for the CG artists to get a better sense of how the light would behave on the sets with the textures used for the miniature versions?
I’d also be very curious, how this workflow compares to the miniature New York set of “The Hudsucker Proxy.”
Some shots were used as a 'foundation' for effects work, yes, but what was used was really very limited. I shot one miniature as a reference for VFX and that was for the wide shot of the Wallace records Library. They transferred the way the light moved on the live action maquette into the final composite and well as the live action element of the actors. There was also miniature work used on some exterior views and this was done in picture. For instance, the view outside the Police station was a miniature as was the view outside K's apartment and some rooftop work. I say miniature but I might better describe those as false perspective sets. All this was in camera. The only model that was shot by a model unit and that worked without a CG remake was the tracking shot of the recycling yard.