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Red horizontal lines on negative


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#1 Paul-Anthony

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Posted 28 June 2018 - 03:12 PM

Hello.

I've got these red lines appearing on some images of 35mm negatives ?

Has somebody already had this same problem ?

Thanks.BOITE-1_1.4.1.jpg

P.A


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#2 Robert Houllahan

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Posted 28 June 2018 - 05:03 PM

Do you have a video clip? Does the line stay in the same place?

 

Usually lines (scratches) are vertical as that is how the film runs through the camera and processor.


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#3 Tyler Purcell

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Posted 29 June 2018 - 01:58 AM

What camera was that shot with?
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#4 Paul-Anthony

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Posted 29 June 2018 - 01:25 PM

Hello it was shot with an Arricam LT.

The line behaves exactly like a scratches it moves a bit, never seen that before. We checked and the line does not appear on the negative, we suppose it comes from the Scanner, it is a ScanStation from LaserGraphics.

I will keep you posted.

Thanks .
 


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#5 Perry Paolantonio

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Posted 29 June 2018 - 02:48 PM

The line behaves exactly like a scratches it moves a bit, never seen that before. We checked and the line does not appear on the negative, we suppose it comes from the Scanner, it is a ScanStation from LaserGraphics.

 

 

In scanners like the scanstation, the film "floats" in the gate from frame to frame, by design. That is, it's never in exactly the same position from frame to frame when the sensor captures an image of that frame. The scanner is always overscanning the film to include perfs and in some cases film edges, which it uses to register each frame digitally, after the frame is captured. An issue with the sensor (pattern noise, dead pixel, tap mismach, etc), will always be in the same position on the sensor. But because each captured frame is in a slightly different position, once those frames are registered any sensor noise will appear to bob around a bit, relative to the picture. 

 

If you see that, then there may be an issue with the camera in that scanner. The scanning service can easily test this by loading the film and running the section where you see the line, with the scanner in overscan mode, with optical registration turned on and turned off. If the line is steady while the registration is OFF, and if the line moves when the registration is ON, then the issue is in the scanner. 

 

In some cases, operator recalibration of the sensor will address problems like this. In others, Lasergraphics needs to log in remotely to do it. 

 

Can you post like 2-3 seconds of footage somewhere at full res (ProRes or something similar?).


Edited by Perry Paolantonio, 29 June 2018 - 02:55 PM.

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#6 Robert Houllahan

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Posted 02 July 2018 - 03:19 PM

Yeah as Perry said it is likely the CMOS JAI camera in the Scan Station.

 

Usually a line (column) defect like this is more likely on a CCD camera but I can't think of another thing which could cause this type of picture issue.


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