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Problem with Nila led lights

Michael Patterson

Michael Patterson

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I was on a shoot a couple of days ago and my lighting guy was using one of his NILA Boxer led lights. As soon as he powered it on, weird horizontal lines/banding showed up evenly across the frame. I tried dialing it out with shutter speed adjustments, but they just changed size a bit. The weird thing is, is that it seemed to not be linked to where the light was pointed. We turned the light completely away from the scene and the lines were still there. We powered it down and then gone. Has anyone else had this issue? The lighting company I hired was blaming my Scarlet because they didn't think that their $3k light could be to blame. He said he has never had a problem before, but also doesn't do a lot of RED work. Seems a shame because the light was pretty bitchin' and I have a shoot again with him tomorrow where it would be a great asset.
 
It will be a CMOS rolling shutter artifact. CCD sensors may not see it which may be why it has not been previously observed. If you changed frame rate, maybe the bands might have started to crawl up or down. My guess is that he had the light plugged into mains power. The rectifier in the power supply may not be smoothing the DC power enough causing a pulse in the light level at a harmonic of the power supply frequency or actually generating the harmonic, either by deficient desgn or component like a capacitor deteriorating.

If there is a high frequency inverter in the mix, or the light itself has some sort of electronic power managment, the same thing may be happening. It may not happen with a lower resolution CMOS camera like an EX1 with fewer pixel rows or might not be so apparent or the bands might be of a different spacing. My guess is it will be there to be seen if some looks hard enough and that some digital SLR cameras will also see it against a plain background, maybe as a different artifact. In that circumstance, the artifact might be there waiting to ambush to show itself during levels and colour grading.

Please do not pay particular heed to my comments. Better brains more competent than mine will comment soon enough.
 
Hmm. If the Nila Box was not actually projecting light on the scene in front of the lens, then I would start to wonder if there is RF interference going on. What monitor was the artifacts showing up in? An on camera LCD, a production monitor (possibly with a long SDI cable acting as an antenna), etc?

If it comes up again and time permits, might try recording a few seconds and looking at the footage on a laptop, to check if it's something actually being 'seen' by the lens and sensor, or if it's some form of interference affecting the monitoring chain.
 
It was on the 5 inch touch and the HD-SDI feed. Next time I'm with him, I'll see if I can't record a bit.
 
Also to think about, how were you powering the camera? Were you on AC? If so try changing the power feed of both the lights and the camera. Although I don't really expect that to be the issue. The above RF idea sounds much more plausible.

I'm a lighting guy by trade so I'm used to lights ALWAYS being blamed for audio hums and video hum bars. :banghead:
 
This is an old thread, but I am wondering if the problem was ever resolved? I am having the exact same issue with the Nila JNH and Boxer lights and my Dragon. The horizontal banding only appears when the fixtures are dimmed down.
 
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