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Problems with dark lines

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#1 federico bonino

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Posted 06 November 2013 - 08:36 AM

Hello everybody!

I have a problem when I take videos with NEXIMAGE CCD. In all cases appear some dark lines that is very difficults to remove.
I have seen that it is possible to minimize them by adjusting the tuning, but not possible to eliminate them.

Could any one told to me if this is a normal effect?
How is the procedure to eliminate them?.

Thanks to all
I attached an image like example
Federico

Attached Files



#2 Tapio

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Posted 06 November 2013 - 09:13 AM

I guess you are suffering from Newtons rings.
Two ways for cure
1. Tilting
http://zwoug.org/vie...php?f=24&t=1395
2. Flat fielding
http://www.cloudynig...4999954/Main...

#3 bunyon

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Posted 06 November 2013 - 09:56 AM

Yes, that looks like Newton's rings. I cured the ones in my system by purchasing a tilt-adjuster from OPT. If they aren't bad, flat fielding may work. You might play around trying to manually tilt the camera to see if you can get rid of them.

#4 federico bonino

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Posted 06 November 2013 - 10:11 AM

OOHHKEY Tapio!!!! Excellent!!! Thnaks very much!!.

I did not know that such problems exist.

So Them If I understund good, the problem is due to a difference of parallelism between the camera chip and the device of PST Them maybe I should check first the condition of setting between the diagonal & CCD.....

OK OK thanks very much by your usefull help!!
Best Regrads
Federico

#5 federico bonino

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Posted 06 November 2013 - 10:35 AM

OK Paul Thanks!!

OK so them, I start trying moving the camera, them if I don´t eliminate it, I try with flat frames.

Thanks a lot!

#6 Paul Hyndman

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Posted 06 November 2013 - 07:17 PM

Take care to ensure the camera is solidly mounted (droop-free), as even a miniscule variation from square (orthogonality) can introduce the "rings". As Tapio mentioned, a tilt adapter can help dial them out, if finessing the mounting alone does not do it.

My preference has always been to hone "front-end" techniques that improve the quality of the raw images, thus requiring the least amount of post-capture processing "magic".

But hey... a big part of what makes this stuff so much fun is the challenge (and sharing our notes)!

Paul






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