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quick fluorescent correction

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Bob Cole
quick fluorescent correction
on Jun 13, 2012 at 5:40:42 pm

I'm shooting a lot of very quick run-and-gun interviews, often with the subject in the foreground lit by a tungsten broad inside a Chimera, and an office setting in the background. The offices are often lit by overhead fluorescents of about 3800-4400K. The result is a slightly green-looking background, even when I try to split the difference in color temp in the camera.

I'd like to put a filter on the Chimera to improve the color balance, and was looking at Lee's website, which recommends their 219, 242, and 243 for that range of correction.

I'm shooting with a Sony EX1R, so I could also make some corrections with Picture Profiles, but I would rather make the basic lighting set-up as good as possible.

Your advice and experience with this would be most welcome.

Bob C


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Rick Wise
Re: quick fluorescent correction
on Jun 13, 2012 at 7:38:28 pm

You've got the basic idea: add green to your chimera to match the green of the fluorescents. Then white balance to your chimera and see how everything looks. You may also find the background is too blue, in which case add a bit of blue to the chimera and re-white balance.

I would carry 1/4 plusgreen, and 1/4 CTB, with enough sheets to double up if 1/4 is not enough. If you want to fine-tune more, also carry 1/8 plusgreen and 1/8 CTB. In general I would also carry some 1/4 CTO to warm things up if you want to go that way.

Note that you could find the "correct" white balance and then add say 1/8 or 1/4 CTO to your key to make your subject a bit warmer than the background.

Ideally you'd have with you rolls of: 1/8, 1/4, and 1/2 of all of the above. That can get pricey.... though with care what you use once can be recycled many more times.

So many ways to play!

Rick Wise
Cinematographer
San Francisco Bay Area
http://www.RickWiseDP.com


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Bill Evelyn
Re: quick fluorescent correction
on Aug 1, 2012 at 2:43:33 pm

Hey, Rick

In this type of set up, are you using a color monitor to help you balance light, or your experienced eye? If a monitor, do you simply calibrate the monitor (with your eyes) using color bars so the blacks, reds, etc. look fine to you (versus a scope)?

We have several guys sharing the same equipment, and the monitor I use never looks the same. So, I hesitate to say "this monitor's right" and light from there. Instead I have to light mostly from how it looks to my eye, practically ignoring the color monitor. I'd like to rely more upon a monitor if I can get it correctly calibrated each time I use it.

Thanks,

Bill


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Rick Wise
Re: quick fluorescent correction
on Aug 1, 2012 at 7:23:18 pm

There are several different ways to tackle this issue of color balance along both the red-blue and magenta-green color axes. One is to use a color meter. Those, alas, cost around a grand, though you can find good used ones for less. Whatever "correction" the color meter gives you for a specific light, usually it's best to apply only 1/2 the correction.

Another is to work with a professional monitor. Your observation that every time you use the shared monitor it looks different is no doubt because other users are tweaking it to look "right" without actually setting it up correctly. Here's one of many articles about setting up CRT monitors. http://spareroommedia.com/video/monitor_setup.html.

Whatever method you use, manually white-balancing the primary shot to a gray card or piece of true-white paper set in the dominant light of the scene is probably going to give you the best results. Sometimes you may want to warm up the scene slightly by placing a sheet of 1/8 ctb set in front of the lens as you white balance. Equally, if you want a cooler look, set a sheet of 1/8 cto in the front of the lens. The camera will correct for the extra blue in the first case, rendering the scene warmer, and the opposite in the second case. If you can trust your editor to correct in post, it may be better to let him/her make that adjustment later. Do shoot a cu of a gray card in that dominant light to give the editor a handle on how the colors are being recorded (after you have made all your changes, but before you actually shoot the scene.)

Relying on the eye is difficult because we adjust our vision to the circumstances. A piece of white paper under fluorescent appears to us to be white, and then again white when we put it in either shaded or direct sunlight. Photographically, they will be very different. However, with a lot of experience, some gaffers and cinematographers can spot green or other casts.

Rick Wise
Cinematographer
San Francisco Bay Area
http://www.RickWiseDP.com


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