Flickering in footage C300

D

deems

Member
Hi.
I had a shooting with theater light ( spotlights ) and now I have flickering in the footage.
Is it a shutter problem?
What is a good shutter setting with spotlights, and LED light. ( I can't see the flickering in my display during recording )
I always have a little flickering with this sort of lights.

Thanks in advance.
Regards, Johan
 
What you're experiencing is a phenomena of pulse width modulation, which is a method of dimming the light intensity in LED sources. It's a problem with all CMOS sensor cameras at the moment, until global shutter sensors become the norm. It can sometimes be mitigated by dialing in a custom shutter with the clear-scan feature.

Adam Wilt has more information on PWM and it's ramifications here:

http://provideocoalition.com/index.php/aadams/story/pulse_width_modulation_is_not_your_friend/
 
Hey, thanks very much for this post. I've had this occur recently using battery-powered LED lights and couldn't figure out what was going wrong. I'll now use the lights only on full pwer and use ND filters if neccessary.
 
Didn't know about this, as yet not shown up on any footage shot under LED lights on my C300, but will test them all out.

Many thanks for posting.

Forewarned is forearmed.
 
Andrew S said:
Didn't know about this, as yet not shown up on any footage shot under LED lights on my C300, but will test them all out.

Many thanks for posting.

Forewarned is forearmed.
Click to expand...

It generally doesn't apply to LED film lighting, at least I've never encountered it. Where it really happens the most is with LED stage lighting like this: http://www.chauvetlighting.com/chauvet-pro/

The slower your rolling shutter, the more apparent the artifacts will be.
 
It definitely happens with some (not all, just some) dimmable LED lights. Example is the Yongnuo YN-160, that definitely causes the issue. When used at full power, there's no problem, but dimming the lights brings the problem into being.
 
As an interesting note, I've also had the same artifact show up on a 5D Mark II when shooting a flickering candle.
 
I've had this issue with chinese LED's. Keep them at full power and there is no issue. Many of them don't cause problems but when they do you'd better catch it or you are in trouble. not a whole lot you can do in post.
 
and most of the Chinese LEDs & Florescents have ALOT of green in them.....you don't see it so much with your eye, but you will with the footage you shoot. We are regularly approached by distributors bringing in the latest from China and we usually put a color meter on them and bingo, lots of green...so we politely say no thanks.....

Jim Martin
Filmtools.com
 
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