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flicker trouble


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#1 Thomas Smith

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Posted 18 August 2008 - 03:31 PM

Hi,
What's the exact shutter angle to avoid flicker in a 50hz country at 23.98P?
I'm going to shoot with fluorescent lights and don't have electronic ballasts.

Thank you in advance.
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#2 John Brawley

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Posted 18 August 2008 - 04:41 PM

Hi,
What's the exact shutter angle to avoid flicker in a 50hz country at 23.98P?
I'm going to shoot with fluorescent lights and don't have electronic ballasts.

Thank you in advance.



You should be fine. We shoot at 24 FPS all the time with no worries. If you really wanted to be fussy you could shoot at 172.8.

jb
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#3 Nathan Martin

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Posted 18 August 2008 - 08:39 PM

as long as the fluorescents arent really old they should have a high cri, so they should be fine.
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#4 Thomas Smith

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Posted 18 August 2008 - 09:17 PM

Thanks,
I was worry because I've always feel some flicker on video images.

cheers.
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#5 John Sprung

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Posted 19 August 2008 - 12:10 PM

CRI and flicker are completely separate issues.

CRI is a subjective measure of how closely human vision perceives the color of flourescents matching Planckian sources such as incandescents and the sun. It doesn't mean much as far as film or video color is concerned. Operating temperature can vary the amount of energy in the 546.1 nm green spike, so a flourescent may photograph greener as it warms up.

Flicker happens when you have a beat frequency between twice the power line frequency, which is the flourescent pulse rate, and your frame or field rate.




-- J.S.
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