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fluorescent with tungsten l


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#1 davidWY

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Posted 06 November 2005 - 09:07 PM

Hi,

Forgive an old question.

I need to mix flourescent and tungesten to have enough light for this interior scene.
I have 2x750w 3200k and one 450w 3200k. Not a lot of light but not a lot of budget. The scene has overhead flourescent lighting with on a 10 foot cieling.

I will be shooting kodak's 7218 S16 bleach skip.

Thanks
David
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#2 Laurent Andrieux

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Posted 06 November 2005 - 09:23 PM

The thing is you don't tell us much about these fluo lights there is on your set...

Do you have the possibility to Color meter them ? If so, mind the CC (Color Correction as well), usually these lights may have a green or magenta cast that can be a problem...

Correcting them therefore needs + green and - green gel.

You can either correct them or your T lights as them to match the fluo bulbs... and then color correct in post.

Usually, it's usefull to have all the bulbs brand new, at least. Having a look at their references can be helpfull as to know their carachteristics, that you should be able to find on the net.

Jhon Pytlack posted a very usefull refernce page to many diffrent ones, make a research on the site.

Also, just observing them by eye can make you find out if ever they don't look all the same, for what is about their color carachteristics...
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#3 David Mullen ASC

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Posted 07 November 2005 - 12:39 AM

Flos range from near tungsten balance to near daylight, plus some have a lot of green in them as well, while some have less green in them. Do they say "Cool White" or "Warm White" on the tubes?
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#4 G. Stephen Bruno

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Posted 07 November 2005 - 11:41 AM

Forgive me davidWY for twisting your question....

I am producing a 16mm short film which has scenes inside a Grocery store. I am thinking about shooting the whole film in 7222 or 7231 B&W negative. If i use the overheads (which are fluorecents) will i be okay...
or is there somthing i'm missing? I undersand the green cast with "color", will this have affects in the b&w...

Again Sorry for twisting the post, didnt want to jar up the board with another one


-G. Stephen Bruno
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#5 David Mullen ASC

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Posted 07 November 2005 - 12:00 PM

The only thing you have to worry about is flicker, not color, if you are shooting b&w under store fluorescents. So shoot 24 fps crystal-sync.

That and grain & sharpness, since all that soft lighting may look too flat in b&w, and will make the grain of 7222 stand out. Find a way to add some contrast to the light.
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#6 Seth Mondragon

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Posted 07 November 2005 - 12:09 PM

David Mullen wrote:

The only thing you have to worry about is flicker

I've seen the flourescent flicker in some people's footage....if you properly gel the fourescents, will you still get the flicker? Otherwise, is there anyway to avoid the flourescent flicker?
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#7 David Mullen ASC

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Posted 07 November 2005 - 12:24 PM

Gelling has no effect on flicker, only color & brightness. Flicker is due to the fact that these are 60 hz (in the USA) AC discharge lamps that are pulsing with the AC cycle, so the camera has to be in-sync with them.

24 fps at crystal-sync is generally considered "60 hz flicker safe". At 24 fps with a 180 degree shutter, you get about 2 1/2 (or 2 1/3?) pulses per frame exposure (with a 144 degree shutter, you'd get exactly 2 pulses per frame).

As long as you CONSISTENTLY get that many pulse per frame, you won't see any flicker, hence why you have to be shooting at crystal sync at a "safe" frame rate. If you fall out of sync with the 60 hz sine wave, you may get more or less exposure per frame, which appears as flicker.

This is not the same thing as a malfunctioning fluorescent ballast or bulb that is visibly flickering even to the eye. The type of "flicker" I am talking about is invisible to the eye.
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#8 G. Stephen Bruno

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Posted 07 November 2005 - 12:35 PM

Thank you David, that makes sense.. any suggestions on creating contrast..( flagging, stronger keys..etc)?
I really just want to use the overheads as ambient lighting.
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#9 David Mullen ASC

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Posted 07 November 2005 - 02:13 PM

any suggestions on creating contrast..( flagging, stronger keys..etc)?


You named it. Stronger more directional keys (especially with b&w), some flagging for negative fill, etc. And try to art direct / costume design for more contrast, like use darker clothing. In flat lighting, a black shirt, for example, will provide some contrast. If you have enough stop, you could consider using Plus-X pushed one stop for more contrast than normally-processed Double-X.

Edited by David Mullen, 07 November 2005 - 02:14 PM.

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#10 davidWY

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Posted 07 November 2005 - 06:17 PM

Thanks for the help.

Without a color temp. meter I have compared the flourescents with my tungsten by eye and they definately are green. So I have ordered a varietly of +green gels for the tungstens to attempt to match them by eye. I will shoot with an LLD and get the rest of the color correct in post.

Hopefully this is reasonable.

Thanks again.

David
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