Color Issue when using HD Lens with URSA Broadcast G2

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tvrepairguy

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Color Issue when using HD Lens with URSA Broadcast G2

PostTue Mar 28, 2023 8:44 pm

I have encountered a strange issue when using a Fujinon ZA17X7.6BERM-M1 HD Lens with our URSA Broadcast G2 Cameras. We are recording several nights of a play using 3 URSA Broadcast G2's. 2 cameras have the Fujinon LA16X8BRM which have worked flawlessly and the other has a Fujinon ZA17X7.6BERM-M1. When the camera with the Fujinon ZA17X is zoomed in to a certain point with certain lighting on stage the Red image signal shifts and gets unaligned with the Green and Blue. If we zoom out the image corrects itself. This has happened with 2 different Fujinon ZA17X7.6BERM-M1 lenses and it seems to happen in the same parts of the play if the camera has the same shot for both performances. We first noticed it in the 1st Act of our 3-24 show and I swapped lenses but it happened again the next night 3-25. I was actually able to capture it both nights since it happened while we were recording on our ATEM SDI Extreme ISO.

I've uploaded 4 clips to my google drive. They cover the same 2 parts of the show on 2 different nights.

You can view them here:
https://drive.google.com/drive/folders/ ... nglJbZc0in

Here are timestamps for when the problem occurs and when it goes away. On all the clips, except the last one you can see the camera performing correctly then when either the lighting changes or the camera zooms in the red signal shifts, then when zooming out or the lights change the problem corrects itself.

3-24 CAM 7 FIRST SCENE
(https://drive.google.com/file/d/15ZgBx5 ... 9godH/view)
Problem Start: 01:30
Problem End: 01:48

3-24 CAM 7 SECOND SCENE
(https://drive.google.com/file/d/1wmygrT ... lY9eX/view)
Problem Start: 0:26
Problem End: 03:40
(The 30 seconds of black was from power cycling the camera)

3-25 CAM 7 FIRST SCENE
(https://drive.google.com/file/d/1s8INdW ... nuLxT/view)
Problem Start: 01:22
Problem End: 01:51

3-25 CAM 7 SECOND SCENE
(https://drive.google.com/file/d/1stUUnS ... FN-sn/view)
Problem Start: N/A
Problem End: N/A
(Problem did not occur, included as a reference)

Has anyone else encountered something like this?

Any thoughts on how to remedy it?

Thanks,
Bob Ramsay
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Howard Roll

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Re: Color Issue when using HD Lens with URSA Broadcast G2

PostWed Mar 29, 2023 7:45 pm

It's not the lighting or the lens. Unfortunately that's the camera.

The red channel is expanded horizontally 10% when the glitch occurs. Subjects in the center of the frame look somewhat normal but the channel offset becomes larger at the edges of the frame. There's not a lens defect or typical lighting setup that would create that effect. I'd consider the timing of the glitch a coincidence.

If you're using camera control maybe there is a bad packet of info that's sending the cam off into space. ISO would be my first guess but who knows. If you can figure out what's causing the effect perhaps it can be avoided. As is, I'd send it back to BM for evaluation.

Good Luck
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tvrepairguy

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Re: Color Issue when using HD Lens with URSA Broadcast G2

PostWed Mar 29, 2023 8:06 pm

Thanks for the reply.

I would agree with your answer regarding the zoom control however on the 2nd clip, 3-24 CAM 7 SECOND SCENE the glitch occurs after a lighting change but without the zoom changing. Also, if you have time, please look at that clip starting at about 3:30. I was trying to troubleshoot and zoomed in and out a couple times and the glitch pops in and out.

On that camera we are using a Fujinon zoom control connected directly to the 12-pin port on the lens, not the Blackmagic zoom if that makes a difference.

We figured out that we can avoid it by keeping a wider shot.

We are taping again tomorrow night. I am thinking about swapping this camera for another one and seeing if the glitch happens with a different camera but the same lens. I could also try swapping the zoom control for a Blackmagic zoom or another Fujinon zoom.

What would you suggest I try in order to pinpoint where the glitch is occurring?
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tvrepairguy

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Re: Color Issue when using HD Lens with URSA Broadcast G2

PostFri Mar 31, 2023 6:55 pm

Update:

I think I fixed it. Had a show last night and no glitches. I did swap the ZA17X for the HA18X lens but I also ran the "Calibrate Image Sensor" function in the Settings. I think the calibration fixed it but it could have been the lens or a combination of both.
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BennoZ

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Re: Color Issue when using HD Lens with URSA Broadcast G2

PostSun Apr 02, 2023 10:56 am

Unfortunately it’s a reflection problem in the B4 mount. By the way, the Ursa Mini Pro doesn’t have this problem because of the different B4 mount.
I’m having problems with a Canon HJ11 when filming into bright subjects while zooming. It’s fixed for about 80% by putting special black ‘tape’ in the B4 mount (by a professional reseller).
I’ve posted a picture somewhere on this forum.
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Howard Roll

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Re: Color Issue when using HD Lens with URSA Broadcast G2

PostSun Apr 02, 2023 9:01 pm

BennoZ wrote:Unfortunately it’s a reflection problem in the B4 mount. By the way, the Ursa Mini Pro doesn’t have this problem because of the different B4 mount.
I’m having problems with a Canon HJ11 when filming into bright subjects while zooming. It’s fixed for about 80% by putting special black ‘tape’ in the B4 mount (by a professional reseller).
I’ve posted a picture somewhere on this forum.


It’s clearly not stray reflections, did you even bother to look at the clips?

Good Luck
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BennoZ

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Re: Color Issue when using HD Lens with URSA Broadcast G2

PostSun Apr 02, 2023 9:16 pm

No, unfortunately I’m not able to watch the clips. But I had the same problems: shifting in colors which appear and disappear during zooming. With the tape it’s almost gone now.
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Howard Roll

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Re: Color Issue when using HD Lens with URSA Broadcast G2

PostMon Apr 03, 2023 4:31 am

Again, it's not the same.

Stray reflections.

A355CA8E-B6EC-4A22-A231-38DE61F13DD4.png
A355CA8E-B6EC-4A22-A231-38DE61F13DD4.png (433.03 KiB) Viewed 490 times

Something else entirely.

AF_2.1.2.jpg
AF_2.1.2.jpg (548.97 KiB) Viewed 490 times


It's almost like something has gone terribly wrong with the shading file of the lens. B4 cams (and others) use electronic lens shading to correct optical issues. Each lens model has a unique calibration file. Here's some random grab of a before and after. Though in the OP's example the shift is only the red channel and it's only horizontal but it's massive and it happens within the span of a frame. The OP could eliminate this possibility by booting the camera with the B4 cable disconnected and manually zooming to see if the error still occurs. With the lens cable disconnected the cam won't load a profile.

shade.jpg
shade.jpg (208.44 KiB) Viewed 490 times

Good Luck
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BennoZ

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Re: Color Issue when using HD Lens with URSA Broadcast G2

PostMon Apr 03, 2023 5:58 am

Thanks for the picture, I see it’s a totally other ‘kind’ of shift :-)
I meant with ‘shift’ more red instead of shift to left of red. My Ursa has had flare problems (as shown in the picture you posted) as well as strong shifted (so more) colors, mostly red and green.
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Earl R. Thurston

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Re: Color Issue when using HD Lens with URSA Broadcast G2

PostWed Apr 05, 2023 3:32 am

The URSA Broadcast G2 has a built-in Lens Correction feature that switches on by default for certain lenses. It may be getting mixed up in a manner that's over-correcting for a problem that isn't there. Perhaps try turning that feature off and test the affected lenses again to see if it's the culprit.
URSA Mini 4K, URSA Broadcast G2

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