DVX vs. Flourescents

S

SigmaCenturi

New member
Hello,
I'm a long time reader first time poster. I'm DPing a short this weekend thats set in an old diner with flourescent practicals. The budget wouldn't allow us to replace them with Kino flos so we have to leave them as is. Now the sound guy swears up and down that this is a bad idea because of two things: they emit a hum that the mics can pic up and they flicker at a rate that is detectable on camera. Can anyone back up these claims??? I've WBed to Flour. numerous times shooting at 24p and never really noticed any problems but lets just say this sound guy is right and there is a flicker could it not be compensated for by adjusting the phase setting the same way you adjust when correcting for monitor flicker? Now a few stats so you know all the details:
- shutter 1/60
- As wide open as I can get away with
- probably using a pro-mist filter (BTW anyone use these before? good? bad?)
- 24p standard
- Settings mostly neutral but the blacks will be slightly crushed.

- Would the flourescent setting in the camera's menu help in any way besides correcting the color?

So there it is, my question to recap is: How well does the DVX perform under what will probably be a mix of Fourescent and Tungsten?
Your help and advice would be greatly appreciated.
 
Hmmm, I don't know about a hum. That should be something the sound guy can compensate for, maybe turn down the microphone sensitivity or something. As far as the lights flickering, try it out! Just shoot a quick couple of shots, finish them in a quick post session, and see. If there's a problem, you're in deep doo-doo, if not, then go ahead. Record some sound while you're at it and see if there is a hum by listening with some good headphones. Just talk to the managers of the old diner and ask if you can do some test shots during dinner or a little bit after they close or something, assuming you're filming at night. A good minute or two is all you need.
 
You may have an inexperienced sound person, as there are easy pass by filters that can be used in post to remove that hum.

As far as pro-mist filters, if you can get your hands on a black pro mist, I would suggest it. Pro mist filters diffuse your blacks, and leave them looking greyish, black pro mist filters keep you blacks more solid, as you want to crush them, using a regular pro-mist could fight this look.

You could still pick up flicker, because fluorescent flicker often times is incosistant, but if the fluo bulbs and ballasts are new, it may very well be negligable. I would suggest doing a test and seeing if you're getting some flicker. If the bulbs are not all around the same age, you might end up getting some random color variations as well. In any case, I would suggest setting up a test.
 
SigmaCenturi said:
they flicker at a rate that is detectable on camera.
Click to expand...

Many times this happens to people who mistakenly have their shutter set too high. You should be fine with 1/60 or off. But try bumping it up to 1/250 and you'll notice your picture start to sway from blue to orange and back. As far as I know, the Flo setting on the camera is a color matrix that is "optimized" for shooting under fluorescent lights. If that's the look you're going for then good, if not, you'll be fine as long as you manually white balance and don't use the WB presets.
-Ryan
 
Just shot a horror feature under several conditions, a few of which were flor. lit with no problems whatsoever relating to tube lights. Using video really negates having to switch out tube lights anymore. With film it's more of a concern since it's balanced only one way. Video of course does it all, in that regard.

First off, leave the shutter off (no reason to stay with 60 in reality). You might find that going slower in a few places with too low light will be ness. too, unless you have some movie lights (beware of mixing color temps if trying to stay even) Second, white balance for every new room is a must if you want to stay with the same skin tones. Third, use the matrix flor. setting if you want a pretty even color response.

You may find it best to NOT have the perfect color though. It's rediculous to think that all shots need the perfect balance. One shot I did looked simply wonderful where we moved from a room full of Arri inkies to a flor. lit room. It set a visual mood that would have been completely lost had I rebalanced for the tubes!
 
I've shot a bunch of times and used fluorescents that were present as extra lighting. I've gel'd my other lights with 1/2 CTB and then white balanced on a white card under a mix of both lights and had good luck. Other times I've just left the lighting as straight tungsten and lit evrything well enough to warm up the greenish hues you get from the fluorescents. If you are really ambitious, you can put CTO gels in the flourescents (depending how big a room, and how many lights there are) and you can count on loosing at least 1 stop if not more. There are flourescent lights at any Home Depot and Lowes that are Color Temp 3000 C (close to tungsten at 3200 C)

Try doing some quick tests if you can. Take a few small lights and a volunteer and shoot a little to see what it will look like.

Good luck.

Jeff Patnaude:thumbsup:
 
sometimes I like to shoot under uncorrected fluorescent light and then use small lights gelled with a VERY heavy red gel and then some heavy blue gel on the backlighting and finally some low fill using a 20k with a heavy green gel. It looks great.


But then I remember that I'm not shooting Dick Tracy - and I slap myself in the head.
 
regarding the sound: Your sound guy isn't as inexperienced as some may make him out to be. What he's worried about isn't solved with adjusting mic sensitivity because the buzz isn't a result of air being moved around that a mic diaphragm picks up. The buzz is electrical and acting on the electronics of the mic itself.

The problem is that the noise from a flouro. isn't like a DC off set hum or a 60 cycle humm. It's true that you can apply a narrow band filter to eliminate this humm. However, they're not ideal as the frequency of the hum is at a frequency close to the frequency range of the human voice.

The human voice typically resonates between 100hz and 3khz. The buzz of flourescent lights is right in this range. So, applying a fliter, even a narrow one, can cause you to lose some of the intelligibilty of a speaking voice.

It may not be dramatic on TV set speakers, but I've found it to be noticable on many speakers and annoying with certain voices in certain rooms. When you take your time and tweak the frequency carefully, making changes in the mix AND when you have other, ambient sound in the mix you can help this. But I'm not going to tell you it absolutely won't be annoying, because it could be.

Just be prepared for the possibility that it's a problem and you and the sound mixer may have to make some compromises to be happy with the end product.

MAKE SURE you sound mixer takes ambient room tone withOUT the lights on first so he has some pure room to work with, this will help a lot.

Also, the light buzz could be more problematic with some speakers than others depending on: where they are in the room (resonances), the frequency range of their particular voice relative to the lights, and where the mic is aiming.
 
We shot a scene in a laundry mat entirely under the old fluorescents (which I thought looked great for the scene) and had no flicker issues. Shutter was set to 1/48th if I recall. We did exerience the color shifting described by HybridCreations however, but it was so slow and gradual it was unnoticeable until we played back the tape at faster than normal speed. If I had to do it again, I'd shoot at 1/60th which I'm pretty sure would eliminate such cycling. This applies to NTSC land of course. For PAL you'd want to shoot at 1/50th. Leaving the shutter off results in a 1/60th sec shutter default - video standard.
 
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