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LED Flicker on Camera Advice for lighting for Camera...

#1 User is offline   Frag_Me 

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Posted 13 December 2009 - 02:34 PM

Hello Folks,

I was involved in a production the other day which used some fairly good but slightly cheap KAM LED fixtures to light the back wall. It looked great live but I noticed when watching a recording of the event that the LED light on the back wall flickered terribly.

Is this something which can be avoided by using better quality LEDs or is this something that affects most types of LED? I know that some of the latest products (e.g. the VLX) are billed as being flicker free for TV work... Would something like, say, a colourblock DB4 look better than these KAM fixtures? What causes this strange activity? Are there other light sources which have this same problem (Metal Halide? Flourescent? Plasma? Sodium?)


Just interested!



Cheers...

#2 User is offline   paulears 

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Posted 13 December 2009 - 03:00 PM

I'd check you weren't accidentally working with a high shutter speed set. LEDs appear to do odd things once you get above 1/120th second.

#3 User is offline   musht 

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Posted 13 December 2009 - 03:19 PM

Most LED dimming schemes use Pulse Width Modulation, which varies the on to off ratio to vary brightness. Subject to paying CK tax in U.S.

This means the LED is flashing many times a second, no filament lag ,LED on and off time is measured in millionths of a second.

Many times a second , can mean a very low PWM rate on something that has been cost engineered too sharply or is just not a great design, price has never been a guide to quality with LED stuff.

#4 User is offline   themadhippy 

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Posted 13 December 2009 - 04:34 PM

pwm dimming and monitor refresh rate my guess matey,also good fun watching a rotating machine lit by a florry tube.
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#5 User is offline   GridGirl 

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Posted 13 December 2009 - 07:36 PM

I had almost exactly this problem a year ago - check out this thread where there were some quite helpful answers!
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#6 User is offline   JonM 

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Posted 14 December 2009 - 09:30 AM

I know it's not overly detailed but there is a section here which outlines the problem, under the section LEDís, Dimming and Cameras.

Jon

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