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Old August 29th, 2008, 12:56 AM   #1
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flourescent lights for green screen

I am looking into flourescent lights for Greenscreen work. I noticed on the Kino page they have a specific bulb recommended for Greenscreens. Has anyone worked with these? Will this be a dramatic difference compared to the standard bulbs in the Coolights.biz flourescents? Can the Kino bulbs be used in the Coolights.biz fixtures?

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Bill
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Old August 29th, 2008, 09:00 AM   #2
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What they have there is basically a green coated version of the standard 55w tube. They also have a blue coated one as well if you want to do bluescreen work. It's another way to do greenscreen by lighting in green rather than regular lighting on a cyc thats green or blue colored fabric. In this way, they make the cyc green with lighting rather than the material of the cyc itself. The technique has been used quite a bit for motion picture SFX work, I don't know how much its really used in video and digital mediums. At least I haven't heard of its use very widely. Most people these days using video cameras and doing green screen work are just putting up a green colored cyc and lighting it with whatever their preference in tungsten, fluroescent of metal halide/HMI.

Normal colored fluorescent (daylight or tungsten) is certainly recognized by many as a good way to go for lighting a green or screen as well as lighting the subjects too (if its appropriate lighting based on what's going on in the composited background of course).

Yes Kino tubes work in our Cool Lights fixtures and our tubes work in there's. The 55w tube is a standard that is supported by many from G.E., Osram, Sylvania, as well as Kino Flo and Cool Lights and tons of other brands out there. Hope this helps.
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Old August 29th, 2008, 09:09 AM   #3
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The downside of using tinted bulbs ( green ) is that you must control the spill.... you don't want that green hitting your subject or your key will be funky.

The ideal source to light a green background is a large, even & soft light source... like the 4 or 6 bank flos from Coolights.biz. You want to minimize any wrinkles or unevenness in the material.

Also... bang for buck.... those 8U 200W tubes with softbox that Coolights.biz sells are hard to beat.... just not as easy to transport fro location work.
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Old August 29th, 2008, 10:28 AM   #4
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Green bulbs are nice but only if you're doing a lot of green screen work and your lights are pretty much set in one location. Lots of VFX guys are starting to gel their green screen lights with green gels which pumps up the green output and reduces red and blue spill. = cleaner key in many instances but again as mentioned, now adds more green to the spill.

For all around fluoros that you can use to light backgrounds and talent, the Coollights are becoming the ones to beat.

If you're looking for green screen material that is very high end and de-wrinkles very quickly, check out EEFX - www.eefx.com


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Old August 29th, 2008, 10:32 AM   #5
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Yes, I've used the kino green bulbs in 4-bank fixtures to light a green screen, it works incredibly well.

The theory of course is quite simple - even the best screen will reflect some light at other bandwidths. The best gel or coating will pass some light at other bandwidths. If you use a gelled or coated lamp on a good green screen, you've reduced the reflection of other colors significantly. BTW, there are gel products specifically for this technique as well.

The first time I saw the green as a single, tight, lonely dot on a vectorscope I was sold - you can certainly key with conventional techniques, and I have, but this works great.

Regarding spill, the best control for direct green spill and spill reflected off the screen remains increasing the distance between the subject and the screen (& screen lighting), and good back & hair lights as needed.
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Old August 29th, 2008, 12:08 PM   #6
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Thanks for all the great replies. This has given me a lot to think about. I will keep you guys updated as we progress with the project.

Thanks!

Bill
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Old August 29th, 2008, 04:33 PM   #7
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Examples attached

Here are some samples from a recent shoot. Put them in your NLE - very nice green! We ran it up to about 65+ IRE, this was a full studio shoot with all the bells and whistles, including the two Kino 4-banks with green bulbs for the screen and all tungsten for the subject lighting. Check out that screen shot - put it on the vectorscope - it is GREEN and nothing else.
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Old August 29th, 2008, 08:08 PM   #8
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I've done a similar trick with 4100 Kelvin fluro tubes. In 3200K white balance they appear greenish which boosts the color of an existing green screen and gives a more pure color. I've also done the same using daylight to backlight already blue fabric to boost it for a better key.
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Old August 29th, 2008, 09:23 PM   #9
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Quote:
Originally Posted by Michael Belanger View Post
I've done a similar trick with 4100 Kelvin fluro tubes. In 3200K white balance they appear greenish which boosts the color of an existing green screen and gives a more pure color. I've also done the same using daylight to backlight already blue fabric to boost it for a better key.
"Virtual" or "poor man's" green coated bulbs... Great idea. I'm glad someone finally found a good use for 4100K ;-)
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Old September 22nd, 2008, 09:57 AM   #10
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Seth,

Intresting files. I put the green screen in Vegas and keyed it - worked fine, but i did notice that when I put the keyed shot in front of a fairly bright video some of the video bled through the talent.
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Old September 22nd, 2008, 10:47 AM   #11
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Originally Posted by Jim Andrada View Post
Seth,

Intresting files. I put the green screen in Vegas and keyed it - worked fine, but i did notice that when I put the keyed shot in front of a fairly bright video some of the video bled through the talent.
Well, that's odd! I did a quick test in Vegas - seems to work fine with no bleed through. This was done just with the Chroma Keyer filter. There are more tricks you can do with secondary color correction (to even out a bad screen) and chroma blur, but this is a pretty straight key just produced by dragging the eyedropper, then adjusting the thresholds and finally just a little bit of blur.

We used Ultra for the key in the original show - quick access to reflections (on the desk), shadows, and many more controls & tricks. However, when the original shoot is as clean as this one you can key with almost anything :-) Not that Vegas' is a bad keyer - it does just fine. But it is rather basic in that you have to build your own effects chains if you want to do screen correction, spill suppression, or fine chroma blur.
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Old September 22nd, 2008, 11:39 AM   #12
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OK - I tried lowering the high threshold and it all looks good now - bleed-through disappeared.

Thanks much (I'm still just learning about chroma kying in Vegas and thought this would make a good starting point - but never thought about the thresholds until you mentioned them)
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