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TOPIC: Colored upwards moving line

Colored upwards moving line 07 May 2018 13:24 #95411

  • The Dutch Video Guy
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I am filming with GH5S camera's in 4K 10bit 25p with the CNED profile turned on. During filming I saw a purple colored horizontal line moving upwards. When it reached the top, it started al over from the bottom. I thought it was a problem with my GH5S and grabbed another one, but the problem was the same. Even with my iPhone.

Is somebody familiar with this kind of problem, or does somebody knows what the problem causes? I tried different kind of shutter speeds and apertures. I started filming in ISO3200 and 1/50. The white ceiling of the location was lit by a purple LED light.

Is there a way to prevent this the next time or to remove this in FCPX?

Many thanks in advance.

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Colored upwards moving line 07 May 2018 15:12 #95414

  • Tom Wolsky
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What country were shooting in? What was the light source?

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Colored upwards moving line 07 May 2018 15:50 #95417

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The Dutch Video Guy wrote: … white ceiling of the location was lit by a purple LED light. …


It's a lights/shutter frequency mismatch - option A, you recorded with your PAL cam in a 60Hz country (US/Japan), option B) the LEDs were 'dimmed', and the dimmer wasn't a 'pro' one, using freq. of 20-40kHz… 

No, no cheap solution to fix that in post. There are very few de-flicker tools (I had published a free one here @fcpco (plugins/utilities), but that is a very brute one… at last for free ;) ) The commercial ones are much better … and much more expensive.

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Colored upwards moving line 07 May 2018 16:10 #95418

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I am from the Netherlands in Europe. So my camera's are all set to Pal 50Hz. The light source was a LED strip near the sealing and some DJ lights.

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Colored upwards moving line 07 May 2018 16:12 #95419

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So it must be a fault in a dimmer. How is this problem called in English? Sorry for all of my questions.

Again, it is no problem with a mismatch PAL and Europe 50Hz electricity system. The problem is that a horizontal bar is moving (rolling) upwards or downwards.

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Last edit: by The Dutch Video Guy.

Colored upwards moving line 08 May 2018 03:55 #95431

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The Dutch Video Guy wrote: So it must be a fault in a dimmer. How is this problem called in English? Sorry for all of my questions.....


I know exactly what you mean, had it myself, 'wandering' bars in video, or bars even in stills - …

Me no electrician ;) but afaik, there are two techniques to dim LED … the cheap one chops off some 'phase', the expensive one varies super high frequencies (some dozen kHz, compare to the 50/60Hz of AC)

No, in English it's all 'Flicker', whereas in German there's technical (!) differentiation btw Flimmern, Flicker, Flackern ..... :lol:
And, for sure, we have a norm/standard here (IEEE1789) for that …

… to fix it in post (when not noticed on set/rec) search for de-flicker plugins…

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