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Greenscreen Histogram

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joseph wilkins
Greenscreen Histogram
on Oct 22, 2009 at 5:23:51 pm

Just wondering if anyone else has good experience exposing for greenscreen on the eEX1

I heard 50 IRE's is the optimum performance, but I dont know what that means.

When I set my histogram to peak at the "50%" mark (right in the very center) it looks a little bright to me.

Just wondered if anyone has any experience here

thanks!


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Michael Palmer
Re: Greenscreen Histogram
on Oct 22, 2009 at 5:36:42 pm

50% ire on a waveform monitor, is what others recommend.



Good Luck
Michael Palmer


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joseph wilkins
Re: Greenscreen Histogram
on Oct 22, 2009 at 5:39:56 pm

Yes, but I dont have a waveform monitor... I only have my eyes and the histogram in the camera.

What would you say in the histogram would be a good point?

thanks



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Tim Kolb
Re: Greenscreen Histogram
on Oct 22, 2009 at 5:53:36 pm

The idea with a green screen is the amount of difference to the foreground... 50 IRE or whatever number you pull out of a hat is best if whatever you're shooting is quite different from that...

If you're shooting something very light, a darker green will be easier to preserve grayscale...if the foreground object is darker, a brighter background will be easiest to key out.

Renting a waveform monitor would be the best because a horizontal histogram is difficult to use for this purpose.



TimK,
Director, Consultant
Kolb Productions,


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Craig Seeman
Re: Greenscreen Histogram
on Oct 22, 2009 at 8:01:52 pm

The poor person's method is with Zebras. I believe they have a ±5 unit range in the EX cameras so if you set them to a number (say 50%) if the entire green screen Zebras you'd be 45 - 55%. Using this is a decent "dirty" method of testing to see if you're lighting the screen evenly.



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olof ekbergh
Re: Greenscreen Histogram
on Oct 22, 2009 at 11:10:51 pm

Well there is always the old light meter.

I still have 2 Luma Pros.

And they are great at checking how even light is and to check how many stops between highlight and shadow.

Scopes of course are the best, but they weigh more than a Luma Pro on location.

Olof Ekbergh


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