Lighting Night Interiors and contrast ratios
Posted 13 June 2012 - 10:50 AM
I have been lighting short, non-commercial films (mostly student stuff) for about a year after graduating from film school, and although I have been learning a lot as I go, there are two subjects in particular that I am still struggling with, and I would really love it if some of you more experienced lighting gurus out there could enlighten me (see what I did there?).
- The first one is lighting night interiors. I am always struggling with the density of the image, and the contrast that will give a nice penumbra look. Most of the night interior scenes I have done feel overlit and flat.
What I have been experimenting with is partially or completely flagging the light off the walls to make the room much darker than skin tone, but I'm not sure if this is the right way to go. Should I underexpose skin tones, and if so by how much? Should I backlight or sidelight the scene to make the edges come out but keep the scene dark? Should I gel the key light to make it warmer?
Of course I understand that observation is key, and that there is no magic formula that will make all night interiors look nice, I am asking for pointers and advice that will allow me to experiment in the right direction and keep improving.
- My second question is a shorter, but more technical one. How much is the look of a given contrast ratio between fixtures affected by different cameras, and their dynamic range? Would a contrast ratio of 3:1 on a talent's face, for example, feel very different on a camera with a large dynamic range like the Alexa, compared to a DSLR? This is pre-colouring, I mean. The question I ask is because of budget concerns, I have been shooting all my projects with DSLR, and I have an opportunity to be working with either a RED Epic or an Alexa in the near future, and I would like to be prepared. Should I be contrasting more, or less? Or go by eye?
I realize this post has been a long read, and I thank you for reading through all of it. I hope it has been clear, and I would greatly appreciate any answers.
Posted 28 September 2013 - 05:26 AM
Too bad there were no answers to your questions because I am in similar position. I see you posted it a year ago, have you got any insights you could share now?
Posted 28 September 2013 - 10:23 AM
In general, yes, if the camera can record a wider dynamic range, you can light with more contrast while still capturing detail. Of course, how you want to color-correct it will matter too. But I don't think a 3:1 lighting ratio on a DSLR versus the Alexa will look radically different if both are viewed with a standard Rec.709 gamma on a monitor, the difference would only be more obvious when looking at the Log-C file of the Alexa versus a Rec.709 recording on a DSLR.
Generally you look at a gamma-corrected image on a monitor when shooting Alexa or Epic, knowing that you are recording a wider dynamic range image in raw or log. It's like the difference in contrast between a projected print versus the original film negative -- you light for the print, but you know that you'll have the extra information on the negative to play with in post.
As for how to expose a night scene, that just depends on what looks right to you. Someone standing a few feet away from a source like a table lamp should probably not be at key exposure, more like 1-stop under to look natural, but if they were closer to the source, they could be brighter. Someone with a hotter backlight or edge light could have less light on their face in comparison because your eye sees a bright highlight so it doesn't feel as underexposed.
If you are overlighting, it's probably because you are lighting by meter rather than by eye -- it's harder to fool your eye. If something looks wrong to your eye, it's probably not going to look right on film. Now with digital, you should be able to see your lighting on the monitor, so there is even less need to over-meter things.
The only side note to that is than in a dark environment, a monitor can look brighter to your eyes... so resist the temptation to underexpose everything until it looks right on the monitor. Same goes for outdoors, resist the temptation to overexpose everything until it looks bright enough on the monitor because in a bright viewing environment, the monitor image naturally feels a bit dim.
Posted 28 September 2013 - 07:42 PM
Generally you look at a gamma-corrected image on a monitor when shooting Alexa or Epic, knowing that you are recording a wider dynamic range image in raw or log.
Quick question. So if your main delivery is TV would you monitor in Rec709 (2.2gamma) and record in raw, slog or whatever (knowing you have more room to spare in post)?
And what If your delivery was a DCP or cinema release what would you monitor in then? Still Rec709, knowing you could both delivery for TV and cinema release fairly easily?
Posted 28 September 2013 - 07:44 PM
For DCP I'd have formulated a lut for the project proper which I'd look @ on set if @ all possible. But sometimes all you can get is REC.
Posted 28 September 2013 - 07:55 PM
Just depends if the standard Rec.709 viewing LUT suits the look of the project. Usually I'd create some variation of Rec.709 for monitoring -- with an Alexa, it would just involve loading an Arri Look file, with the Epic, it would just involve adjusting the camera settings for chroma and contrast -- it's all just metadata anyway, the main issue is just getting dailies for editorial to match that look. Then the final grade would be from the log or raw originals.
Rec.709 is the standard for gamma and color space for display on monitors. So even for a DCP project, unless you have a monitor that can display P3, you'd monitor in Rec.709 or something similar. I think Redgamma on an Epic camera, for example, uses a curve to fit the dynamic range of raw into something that looks OK in Rec.709, just flatter -- but not milky with underexposed highlights like a log gamma (like RedLogFilm or Arri's Log-C) would look displayed on a Rec.709 monitor.
If the log version if mild enough, like Panalog or C-Log in a Cannon, you can watch it on a regular monitor without a LUT and perhaps just crank up the contrast to compensate. Just keep in mind that the danger then is exposing your highlights so that they look normal in brightness -- most log gamma place white (5-stops over medium gray) at 65% or 70% instead of 100%, in order to record more overexposure information, so you don't want to monitor in log and then expose so that your whites hit 100% because then you'd be losing one of the benefits of log recording, extending overexposure information.
Posted 28 September 2013 - 11:20 PM
Very enlightening, thanks for the responses. One thing that occurred to me is that there is no P3 setting on any of these cameras? Why is this? In the case of a theatrical release wouldn't this remove on of the steps in post? Or would the production actually incur costs from having to use more bespoke monitors/ equipment?
Posted 29 September 2013 - 12:27 AM
We're just talking about monitoring, not recording -- features record raw or log for maximum dynamic range so having a P3 monitor output wouldn't remove any steps in post. Most monitors are Rec.709, all the way through editing, including whatever people watch dailies on, so that makes the most sense for monitor outputs on the camera.
There are very few monitors that can display P3, I think there is one that can even apply a P3 display LUT to an incoming log signal -- but it's not that common. I'm not sure how far off P3 is from Rec.709 anyway in either gamma or color space (P3 is a bit wider, that's all I know.) But if more production monitors offered P3, then more cameras would offer a P3 viewing output. The other issue is whether it would make more sense to monitor in a pseudo-ACES look (something workable within the Rec.709 of the monitor though) if the post is going to go through ACES.
Posted 29 September 2013 - 07:32 AM
Yeah I meant p3 monitoring. As in a LUT applied to the monitor not actually record in P3.
You are right p3 is close to Rec709 but it has a gamma of 2.6 and more saturated greens in its gamut.
I just looked into ACES I hadn't seen that before. Looks very interesting and something that will eliminate a lot of the problems from camera to post.
Posted 11 December 2013 - 10:19 AM
Monitoring can be difficult because if you reduce an image size it will appear darker. Try viewing a film in the corner of your computer a couple of inches wide - it appears much darker than when enlarged. Same with printed photographs for some reason. And monitors have brightness levels which can boost or dim the final image - you need a darn good monitor for viewing images at time of recording. If you use histogram you can make sure your highlights aren't blowing, which don't look very nice on digital - I prefer underexposure to overexposure. Digital isn't very good with blacks - even at 400 ASA underexposed areas will become quite grainy and muddy but it is easier to add more contrast in post than try and get more information back that you haven't captured.
DSLRs have limitations. But considering the price they are very reasonable.