ASI1600MC-Pro strange pattern

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ASI1600MC-Pro strange pattern

Postby philherbert » Fri Feb 09, 2018 9:57 pm


I am having a problem with my 1600MC-Pro. I use it with cooling at -20C, and Unity gain (139). I have done a series of 180 second subs, and they all show some patterning in the background.
Improved results.JPG

The pattern I am talking about are the curving lines, mainly visible in the centre of the above image as light curving lines against the slightly darker background. This image is a processed stack of images. However the same pattern is visible in all of the subs (but fainter and harder to show). I have just taken subs again one month later and get exactly the same background pattern, which has made me think this might be a hardware issue?

You can also see that processing has introduced inverse vignetting that I have been trying (for one month!) to get rid of. Despite many different processing techniques, and using flat frames taken in various ways for various lengths of time, I have been unable to avoid the inverse vignetting (dark in the centre and light outside). The individual subs look ok, it is just when stacked that the inverse vignetting shows up. There are what I assume are dust shadows in the individual subs, so removing the vignetting as gradients doesn't help much. This image shows an individual sub with the dust shadows next to the processed stack.
Sub and processed.JPG

So I have two issues - the curvy lines in the background, and the inverse vignetting. I have spent a month working on the inverse vignetting and have not been able to get rid of it. I now wonder if the two issues are perhaps linked and caused by a hardware issue?

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Re: ASI1600MC-Pro strange pattern

Postby philherbert » Tue Feb 13, 2018 11:48 am


Is this background pattern something that I should expect to see on the ASI 1600MC-Pro? I've attached perhaps a clearer image. This shows the result of stacking two separate sessions, light frames only. I've then run ABE in PixInsight to make it clearer. The subs were taken about a month apart, and yet still show identical background patterns.
Curving lines.JPG

Has anyone else experience this type of artifact with any ZWO camera? I'm a little disappointed at apparently wasting the last couple of months of imaging time (not that there have been many clear skies), with perhaps a hardware problem? Could it be the way that the TEC cooler is connected to the sensor that is producing these artifacts.


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Re: ASI1600MC-Pro strange pattern

Postby GeneralT001 » Wed Feb 14, 2018 2:19 am

Hi Phil,

Myself and a few others have had the exact same issue. I had to send my ASI1600 MMC Pro back to ZWO for repair. They said they had to up the voltages to the pixels? Not exactly sure what that means though. It sux to have to send it back as it took a full month to get it there and back.

When did you buy the camera? It seems most people who are having this issue bought them when they first came out (bought mine in Nov 2017)?

You'll see a couple of other posts here with the same issue (one by RWStanley).

Sam will probably tell you to send it back, but with the Chinese New Year he may be a bit slower in responding - or maybe he already has through CN forum - he's usually pretty quick.
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Re: ASI1600MC-Pro strange pattern

Postby philherbert » Wed Feb 14, 2018 8:24 am

Thanks GeneralT001.

I bought mine in late November. This is the first I have heard of others with the same curvy lines, although I have seen of others with more random pattern noise.

I haven't heard back on this forum yet, but I'd forgotten it was the Chinese New Year this week. I'm also waiting to hear back from the actual supplier, but they may also be having delays communicating with ZWO at the moment I guess.

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Re: ASI1600MC-Pro strange pattern

Postby Astrobug » Sat Feb 17, 2018 6:59 am

When doing NB I get also these results. Especially with OIII & SII.
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Re: ASI1600MC-Pro strange pattern

Postby Sam » Tue Feb 20, 2018 2:26 am

this camera have no problem
sorry to say the color version of 1600 have such pattern
and different sensor have different pattern
you need to take flat to calibrate it
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Re: ASI1600MC-Pro strange pattern

Postby philherbert » Tue Feb 27, 2018 7:58 pm

I'm pleased to report back that the camera supplier was good enough to provide me with a replacement ASI1600MC-Pro to test, and the curvy lines and strong inverse vignetting have gone away, so I'm 99% sure it was down to being a problem with the camera (I changed nothing else in the imaging train or processing).

So far the new camera is producing some promising subs!
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Re: ASI1600MC-Pro strange pattern

Postby TomR » Tue Feb 27, 2018 9:55 pm

That's good news for you, Phil. I am less lucky, though, because I bought the camera (178mc) from the manufacturer in denial mode. Yes, banding patterns are a defect and no camera feature and: no, they won't go away with calibration.
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