High Shutter Speed Problem: Brown Lines under Fluorescent Lamps

[Ilias Papaioannou]

Hello,

I was playing with my camera and I tried to put the shutter speed above 1/120 and I saw some brownish lines: I uploaded the video on megaupload: MEGAUPLOAD - The leading online storage and file delivery service (The video is too compressed, so, low quality but only 10MB).
I was under some old fluorescent lamps. I didn't have this problem with shutter speeds under 1/100 or the problem wasn't noticeable. I tried different frame rates on PAL and NTSC, different Gamma and Martix but nothing. The color temperature was at 5600K. Also I don't have the problem with other light sources.

Any ideas?

Thank you
Ilias

[Dave Sperling]

Looks to me like a fluorescent ballast frequency issue - it's not that there are brown lines - it's just that those are the parts of the frame scan when the fluorescent is giving off less light, so they look darker. The window areas are fine.
So as you have probably already figured out, the solution is to use a slower shutter that more closely matches the line frequency of the current. (probably 1/50th ?) If none of the standard shutter speeds work, Set the shutter to ECS and adjust the speed to minimize it.

[Colin Rowe]

Spot on Dave

[Ilias Papaioannou]

Thank you Dave! I will try to see if it works with ECS. I wanted to do some slomo with twixtor on after effects so I wanted clean frames with high Shutter Speed. I will simply do it under another light source. It seems much easier.

-Ilias