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Old September 10th, 2015, 06:34 PM   #1
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The Great C100 Banding Mystery

Hi Everyone,

I just came back from a shoot in Memphis for a PBS doc. I've been using the C100 without any problems for over a year, then something strange happened. In the middle of a shot, the camera's color balance went crazy and added a strange vertical banding pattern. (The color balance skewed so that it was reading Kino daylight as 3400K.) I'm not sure how this happened and if I can salvage the footage.

I'm stumped and would really appreciate the expertise of the community on this issue. You can download 15 seconds of the video file here: https://dl.dropboxusercontent.com/u/13678501/Ruthie.mov. You'll notice that the banding pattern changes if you resize the video player. Please help! :)

Christopher
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Old September 10th, 2015, 11:16 PM   #2
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Re: The Great C100 Banding Mystery

It might be a bigger mystery than you thought - the clip played perfectly - didn't see any banding or color shift.
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Old September 11th, 2015, 06:03 AM   #3
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Re: The Great C100 Banding Mystery

How deep does the rabbit hole go? Playback is perfect on my system, no banding. Image quality is impressive, which lens did you use?
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Old September 11th, 2015, 08:17 AM   #4
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Re: The Great C100 Banding Mystery

I definitely see it. I have no idea what would cause that. It's very precise too... almost like it is an intentional filter effect.

I've never seen this on anything I've shot with the C300/C100/C100M2. Maybe you should contact Canon about it.

Can you shoot a random scene and see if you still have the issue?
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Old September 11th, 2015, 09:00 AM   #5
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Re: The Great C100 Banding Mystery

Quote:
Originally Posted by Christopher Rufo View Post
In the middle of a shot, the camera's color balance went crazy and added a strange vertical banding pattern.
The use of the term "banding" is confusing. That's not banding. That is fine vertical lines going down horizontally across the frame. They resemble interlacing, but in the wrong direction.

Quote:
The color balance skewed so that it was reading Kino daylight as 3400K.
Do you mean that you were on automatic white balance?

This is a ProRes clip. Did you use an external recorder, or is this transcoded from the internal AVCHD?
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Old September 11th, 2015, 12:10 PM   #6
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Re: The Great C100 Banding Mystery

Thanks for the feedback, guys. Good questions and suggestions.

-Alex, for the lens, I'm using a 50mm Zeiss ZF.2.

-Michael, yes, I've actually fixed the issue after resetting the camera and doing an ABB. But I'm still stuck with this bizarre footage, which I'm hoping I can fix.

-Gary, yes, you've nailed it. It's not banding, it's those bizarre vertical lines down the frame, which when you resize the Quicktime player can change size and pattern.

Here's some more info:

I'm not on auto white balance. I was using a Kino Daylight, so I dialed in the daylight preset, but it was way off. For this shot, I had to do a custom white balance and it read 3400k to get the correct color balance -- way off, had never happened to me this way.

I used a Ninja recorder to get the ProRes signal, although this image issue showed up in the actual C100 monitor and the footage on the CF cards.

Any idea what this could be? Is it something that could potentially be fixed? In a worst case scenario, I can re-shoot the footage from that day, but I'd prefer not! :)

Looking forward to your suggestions...
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Old September 11th, 2015, 06:53 PM   #7
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Re: The Great C100 Banding Mystery

Strange - I watched it REALLY closely - no banding, no lines, no color shift -even at full screen on 30" monitors. It looked really great!
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Old September 11th, 2015, 07:00 PM   #8
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Re: The Great C100 Banding Mystery

Hm, you're not seeing the vertical pixelated lines? It almost looks like what happens when you film a TV screen.
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Old September 11th, 2015, 07:28 PM   #9
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Re: The Great C100 Banding Mystery

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Originally Posted by Christopher Rufo View Post
Hm, you're not seeing the vertical pixelated lines? It almost looks like what happens when you film a TV screen.
It is definitely there.
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Old September 11th, 2015, 07:39 PM   #10
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Re: The Great C100 Banding Mystery

Yeah, it's really bizarre. I tried re-exporting it, I tried pulling the original AVCHD off the original in-camera card again. Same issue. I'm not even sure how to diagnose the problem. Any thoughts, guys?
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Old September 11th, 2015, 10:15 PM   #11
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Re: The Great C100 Banding Mystery

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I'm not even sure how to diagnose the problem.
Set up a test shot with the same light and shoot all internally and see what happens. If it's consistently doing that, then there's a problem with the camera and it will need to be serviced.
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Old September 12th, 2015, 12:33 PM   #12
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Re: The Great C100 Banding Mystery

After I did an ABB and hard reset, the camera appears to be working fine again. So, fingers crossed. When I get back from my next shoot, I'll send it in to Canon to have them take a look.

In the meantime, any ideas if this existing footage can be fixed? I'm still stumped! :(
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Old September 13th, 2015, 11:03 AM   #13
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Re: The Great C100 Banding Mystery

I see it. That is very unusual. Yes, the visibility does vary with screen size, I see it more at it's native resolution than when blow up to full screen on my 27" iMac but I see it in both sizes. I doubt this is it, but it almost looks as if the Bayer filter is offset by a single pixel or something in the imaging block is/was slightly off kilter. But if ABB seems to have fixed it, who knows?

Do you know anyone at Canon Hollywood or at a Canon Service Center? If it were me, I would be showing it to Canon and a video engineer to see what's up. Another long shot would be if you could get Adam Wilt to take a look at it and offer an opinion of what it is and what caused it and if there is any way to fix it. Personally, if it were me, I would schedule a reshoot if you have access to the talent. It could take you a long time to figure out what caused it and if it can be fixed.
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Old September 13th, 2015, 02:32 PM   #14
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Re: The Great C100 Banding Mystery

Quote:
Originally Posted by Christopher Rufo View Post
After I did an ABB and hard reset, the camera appears to be working fine again. So, fingers crossed. When I get back from my next shoot, I'll send it in to Canon to have them take a look.

In the meantime, any ideas if this existing footage can be fixed? I'm still stumped! :(
Hey Christopher - That is really something. Looks like an effect. You should bottle it up and sell it!

On fixing the footage: I got a pretty natural looking result in FCP6 (don't laugh) with a 1 pixel gaussian blur followed by a 25% sharpen filter. End result looks a tiny bit sharpened in playback (a little like 5dmarkiii footage, but better, more detailed)... really not bad, and it completely removed the screen pattern.
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Old September 13th, 2015, 03:11 PM   #15
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Re: The Great C100 Banding Mystery

Nice job, Barry.
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