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Tungsten & Par queries


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#1 Suvikram Bedi

Suvikram Bedi

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Posted 06 February 2014 - 02:47 AM

Hi... Just needed some clarification... If i shoot a project at 25fps (in India) ... And am using tungsten lights, kinos and 6k & 4k pars... And play around with shutter angle (go tighter)... As I want objects falling in the foreground (leaves and stems) to look crisper... Is there a possibility I'd encounter flicker ????

Thanks
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#2 David Mullen ASC

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Posted 06 February 2014 - 10:51 AM

If your 6K and 4K PAR's are HMI's, not tungsten, you should get modern flicker-free electronic ballasts.

 

The problem with short shutter angles and standard 50 or 60 Hz AC magnetic ballasts is that when the shutter time is 1/50th for 50 Hz or 1/60th for 60 Hz, you get two pulses per frame, so when the shutter time is 1/100th for 50 Hz and 1/120th for 60 Hz, you get only one pulse per frame -- so the lamp might not flicker but it might look dimmer depending on where you catch the waves in their cycles.

 

I'm assuming you are shooting with a crystal sync motor on your film camera or are shooting digital.


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