GH2 Live event video recording - horizontal banding problems based on loc. LED-lighting

O

ottowitz

Active member
hello folks,

i have the following problem. i bet it's very well known but i couldn't find the right searching terms to dig how to solve it. therefore this thread:

i did a video recording with gh2 and canon fd 1,4f 50mm at an event. they use led lightning surfaces on the ceiling (blue,green). i patched my cam to one of the driftwood patches which are 24 fps ntsc and i'm located in germany. i know when shooting 24 fps - 1/50 shutter should be the shutter (1/48 in fact, but my gh2 only delivers 1/50s). while recording at the event with this setup the banding of the led lightning was horrible! i changed the shutter speed from 1/40 to 1/120 and the banding was "best" and less obvious in 1/40 shutter speed mode. i switched in camera from ntsc to pal in the main menu BUT i do think that it didn't affect the recording because i used the hacked driftwood patch. right? i know germany (eu) uses 50hz power, usa 60hz and all this stuff).

Can someone direct me to get this problem solved? the banding was still obvious when i used 1/40 shutter and of course i want to use 1/50 shutter with my 24 fps recording for best results...do i need to record in 25 fps in this environment to get the problem solved?

all the best
 
I've come across this problem with LED stage lighting in a music venue. It was filmed with two HVX202s and a Sony HC1 and they all had trouble with the LED lights. We got various banding and exposure issues. No matter how we set the cameras we had some sort of glitch. I had a chat with the guy running the lights and he told me that the LED loaded Parcans he was using get pulsed by the lighting desk pretty much continuously and at different rates to create the different light effects. We found that on certain settings of the lighting desk the cameras coped ok and on others they freaked out. My understanding is that LEDs can be run at lots of different frequencies so setting for 50hz or 60hz may not always fix things. You have to work with the lighting person to find a compatible setting for the camera you are using. My 2c ;-)
 
I don't have any experience with European building LED lighting, but you could be running into a similar issue that fluorescent lights tend to have, a strobing effect due to mismatched frequency and frame rate. If that's the case, 25fps may fix it. Download the new official firmware that does 25fps and see if that fixes the issue. It could also be related to something described in this article (pulse width modulation): http://provideocoalition.com/index.php/aadams/story/pulse_width_modulation_is_not_your_friend/

Good luck!
 
You must log in or register to reply here.
Back
Top