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Old August 20th, 2009, 01:16 PM   #1
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Matching fluorescent and tungsten color temperatures

There is something of which I can never get to the bottom regarding color temperatures.

1. I have yet to see fluorescent bulbs come in 3200K. I've seen 3000K, 3500K, 3800K, 4100K, but not exact tungsten matching. My question is, what post-production repercussions are there, if any, of, for example, using 3-point lighting in an interview where the key is a 3000K or 3500K fluorescent softbox, and the fill light is a 3200K tungsten light?

2. How much does the diffusion material in a softbox (I'm thinking of white material) affect the color temperature of the light that goes through it?

3. How much does CRI matter in terms of matching a fluorescent and tungsten source onto a subject?
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Old August 20th, 2009, 02:25 PM   #2
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I usually put the appropriate 1/4, 1/2 CTB onto the tungsten to match the colour temperature of the fluorescent. You could put a 1/4 or 1/8 CTO on if you want to match to a 3000K light. Video cameras are pretty blind to the green in fluorescents, unlike film, so you usually don't need to worry about that, although some of the new d cinema cameras will show the green.

A lot of this is a matter of what you personally like, a lot of people don't use the correct colour temperature anyway, they often make it a bit warmer looking. You can use a monitor to check the effect.
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Old August 20th, 2009, 02:45 PM   #3
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I had been wondering the same thing specifically about the "tungsten colored" tubes from Kino-Flo:

KIKF2955TL

2900K seems pretty low to me compared to the 3200k from tungsten. I guess you'd need to add 1/8 CTO to the tungsten or 1/8 CTB to the flo tubes to get them closer to matching?
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Old August 20th, 2009, 06:50 PM   #4
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If you're looking in the class of commercial fluorescent bulbs, you won't find any 3200K. Its not considered part of any standard for commercial lighting. Thats something that companies have to manufacture specifically for video/film use since 3200K is a standard there. Plenty of companies carry a 3200K 55w bulb for example.

Kino Flo has a 2900K to match with household type "practicals". I do believe they have a 3200K as well.

CRI matters for mixing with other light. 85 and above and you should be okay for mixing with real tungsten.
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Old August 20th, 2009, 08:59 PM   #5
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Richard to the rescue, as always! :)

Thanks for the info - I've been wondering where to try to get additional lamps for your VERY nice flo's (itching to get to using them, btw) and avoid shipping. Sounds like hardware stores are an option if you're willing to deal with the off-color tubes...
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Old August 20th, 2009, 11:50 PM   #6
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Thanks for your comments. If you can find a 55w tube in a hardware store I'm sure it would work as long as the color temp and CRI are acceptable. But I think they aren't that common and mostly a special order item. I imagine most will have higher shipping for flo bulbs since they require special packaging and handling.
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Old August 21st, 2009, 09:46 AM   #7
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Excellent info.

I am wondering, what is good online supplier of compact fluorescent bulbs (in different color temperatures) with high CRIs (at least 85, ideally 90+)? I am looking to replace one of my fluorescent fixtures with better CFLs.

I am still curious about this "green spike" issue. Obviously video and film lights are tailored to reduce this effect, but if you want to gel a fluorescent with a green spike to make it match another light, how do you know whether you need 1/4 minus green or 1/2 minus green or any other amount?
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Old August 22nd, 2009, 07:33 AM   #8
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Quote:
Originally Posted by Richard Andrewski View Post
If you're looking in the class of commercial fluorescent bulbs, you won't find any 3200K.
Actually Richard, I beg to differ. I have run across 3200K offerings. You just have to look hard.
The other issue you will find, is that even though a lamp may say 3200K or 5600K it might not really be that color temp in use. Many lamps are off by a couple hundred degrees or more.
I know lighting directors that can look at a source and tell you what temp it is. Or look at the spill from an exterior window and guess the color temp exactly. But most people are not that good. That is why I would suggest learning two tools if you want to take this craft to an upper level.
The two tools are ones that many have abandoned over the years for a number of reasons. They might have no longer felt the need to use them since they were no longer shooting film. Or maybe their newer digital camera has those functions built in. The truth is, most newer shooters or young lighting people have never even seen these tools let alone use them. And the two tools are.... A Light Meter and a Color Temp Meter.

With this duo you can quickly figure out your color temp on an exterior, and know which ND filter to use, before your camera ever leaves the truck.
Or instantly know which gel to add to compensate for lamp age, and setup exact lighting ratios.
A color meter will also let you sort through any of the fluorescent bulbs you might purchase, so you will know their exact color.

Good Luck!
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