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Chroma Key on phantom


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#1 Jake Iesu

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Posted 24 May 2009 - 04:02 AM

Hey,
I'm doing a test shoot tomorrow with the Phantom on green screen. Im wondering if anyone has any ideas on what will make the Green Pop on this camera. Being raw capture I'm not 100% on how to tackle it. I shot a few tests a week ago and the green seemed to be very muted, almost milky, it was lit with tungsten lamps and exposed at the same stop as the talent.
A friend has suggested sticking a 1/2 blue on the lamps and under exposing 2 stops, however the
phantom seems to handle things quite different from film, i think if i under expose it, It will be even duller?.
Any suggestions.
Unfortunately I am limited to using tungsten lamps 4k and under.
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#2 Kevin Zanit

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Posted 24 May 2009 - 01:54 PM

I would not agree that it is all that different from any other camera in this regard. You just need a TON of light at the higher frame rates so as to not underexpose it. And if you have the limitations you are talking about in terms of units (as far as I know there are no tungsten units that are 4k, but 5k and under), you may be pretty underexposed depending on your frame rate. Also, depending on your frame rate you will have flicker from these smaller tungsten sources on AC power.

Remember, the Phantom is a daylight balanced camera, so lighting with no correction will underexpose your blues and give you a lot more red than you want, which can definitely affect how the green screen color comes out.

You can white balance the camera, but it is not as good as putting a filter on the lens or the lights. You will loose some latitude. The best thing is to try and get it as close to daylight as your light level will allow. So any 80 filter on the lens or CTB on the tungsten lights would be a good thing.

Kevin Zanit
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#3 Jake Iesu

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Posted 24 May 2009 - 03:30 PM

My mistake on the 4k units I think they are actually 5k Mole pars we have, Blondes and Reds.
I wasn't aware that doing a White Balance actually effected anything at all on the phantom, besides the monitor out that is.
That is a good suggestion to use an 80 on the lens.
In terms of flicker, We shot a few sequences at 600fps and using only 2ks and an 800w or two for kick I did not experience any
lack of uniformity in the image. I will ramp it up today hopefully get around the 1000fps mark and see how we go in the flicker
department, I will definitely be looking for it now.

Thanks for your response.
Jake Iesu
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