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EX-1 flourescent banding - really bad problem here... do you have this issue?

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Mark Palmos
EX-1 flourescent banding - really bad problem here... do you have this issue?
on Jul 6, 2008 at 12:00:08 pm

Hi
I did a shoot in Jan which was mostly great, but certain shots indoors had this darker band, about a third of the height of the frame, passing slowly downwards. It is a very soft band, not like the hard edged band associated with shooting a CRT monitor screen.

I have uploaded something I shot a couple of weeks ago, and now i see it was not some one-off funny radio frequency or some odd interference - which is what I had hoped the initial problem was.

The common factor is that in both places there was flourescent lighting, but then again, not all flourescent lighting causes this problem... but its awful and in the case of the stuff I shot in Jan, worse than what you see in this clip:


http://finalcutpro.tv/EX1_banding.mov

BTW, I have speeded it up so the problem is more obvious.

I have not experimented with shutter speeds etc, the problem being I did not notice the problem while on location, only back in the edit suite.

Anyone else with this problem?

Tx
Mark.



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Craig Seeman
Re: EX-1 flourescent banding - really bad problem here... do you have this issue?
on Jul 6, 2008 at 1:58:11 pm

Mark,

I saw something like this on a shoot I did in a gym with fluorescent lights some time back. I was just testing some "odd" settings that I'd never use though.

Looking at the footage and where your based, I assume everything was 25fps/50hz.

Given this happens with fluorescent lights (and not all of them for sure) it must be that some are refreshing at a rate slightly off from 50hz (or 60hz in my case).

There is a Flicker Reduce feature in the EX which defaults to Auto. I'm wondering if this has something to do with the issue. It's hard to test though when the "flicker" is more of a very slow drift.



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Michael Palmer
Re: EX-1 flourescent banding - really bad problem here... do you have this issue?
on Jul 6, 2008 at 3:37:41 pm

Craig,

The clip I saw ran fast like some frames were dropped but I could see this banding as it is called. I'm wondering if Mark might have turned the shutter off to have fixed this problem, as it seems to be caused by the rolling shutter. This is the first banding I've seen that was caused by flos. I would bet these lights had magnetic ballasts and were not electronic (flicker free) ballasts.

Good Luck
Michael Palmer


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Craig Seeman
Re: EX-1 flourescent banding - really bad problem here... do you have this issue?
on Jul 6, 2008 at 4:25:52 pm

Mark speed up the clip to make the role more obvious. It's very slow. It's what I saw on one of my shoots too. I believe I had the gain cranked and an extremely fast shutter speed. I was just experimenting. For me, the problem didn't exist at "normal" gain and shutter settings.

As noted above, there is a flicker reduce function that defaults to "auto." Given the VERY SLOW nature of the role it's hard to "dial in" a flicker reduce setting (good monitor and being able to spot it over many seconds to test).

In Mark's case, turning off shutter would probably work. In my case it would be an additional problem since I was shooting sports. BTW I had NO PROBLEM with 720p24/60, 180° shutter, +3db gain, which is what I ended up using for my shoot.

I agree with you about the ballasts. It's one of the reasons why I turn off such lights in most shoots.



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Steve Wargo
Re: EX-1 flourescent banding - really bad problem here... do you have this issue?
on Jul 6, 2008 at 5:09:20 pm

We have had the same problem several times over the years with different cameras and recorders. When possible, we turn flos off, or overwhelm the scene with our own lighting.

This is the "flicker" problem that we've had with those lights for years.

Mark P., Can you return to the same location and do some tests?

Steve Wargo
Tempe, Arizona
It's a dry heat!

Sony HDCAM F-900 & HDW-2000/1 deck
5 Final Cut (not quite PRO) systems
Sony HVR-M25 HDV deck
2-Sony EX-1 HD .


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Mark Palmos
Re: EX-1 flourescent banding - really bad problem here... do you have this issue?
on Jul 7, 2008 at 6:47:27 am

Hi guys
and thank you all for your input.

the settings I used were 720p 25fps and i am pretty sure that i would have been using auto setting for the one that was worst (i dont have that footage to show you) but it is so subtle on the camera, especially when grabbing stuff quickly and on-the-fly, that the idea of fiddling with shutter speeds was never an issue. Most of the time, on the quality of work I am doing, I do not take lights, and simply make the most of what's available in a short time, so it HAS to be able to work under regular office fluorescent lighting. (i must try to find that flicker function in the menu!)

i cant return to any of the places where it occurred but will definitely do some tests when my camera is next in use in fluorescent conditions.

tx again fellas, i will report back!
Mark.


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Craig Seeman
Re: EX-1 flourescent banding - really bad problem here... do you have this issue?
on Jul 7, 2008 at 1:24:53 pm

Mark, I often shoot in similar circumstances. The challenge is that one doesn't see the roll if it's very very slow, as in your case. One can tweak the EX1 flicker reduce frequency but certainly the time that would take with a slow roll isn't likely there in such shooting circumstances. Alas, the client has to take some "risk" if they don't provide enough time or money for lights.



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Noi Kristinsson
Re: EX-1 flourescent banding - really bad problem here... do you have this issue?
on Jul 8, 2008 at 9:07:06 pm

I have been having the same problem. But the banding is much faster, and it happens when we're shooting under a very bright conditions outside.

The light changes very fast here, (Iceland) and it seems to happen when the light is between 3200k and 4500k

The flicker reducer was on auto and I perhaps thought it might be related to this. But I have to make couple of tests before I'm sure.



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Craig Seeman
Re: EX-1 flourescent banding - really bad problem here... do you have this issue?
on Jul 9, 2008 at 2:25:29 am

Fluorescent sun with a 3200°K color temperature that changes rapidly. We have a country on Earth called with the same name, Iceland, as your planet. The Sony sells the EX1 on your planet too?

All kidding aside

Do you have such video you could show us? Are you getting rapid color temp changes due to some celestial phenomena or maybe reflections from something or rapidly moving clouds. I'm a bit bewildered.



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Bengt-Göran Bengtsson
Re: EX-1 flourescent banding - really bad problem here... do you have this issue?
on Jul 23, 2008 at 6:35:51 pm

I think you had shutter "on" giving 180degree shutter= 50Hz. The light is running a little higher or lower than 50Hz giving the strobing. Try shutter off giving full frame exposure to elimiate banding.



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