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ASI071MC-Cool Sensor Artifact issue?

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#1 Jon Rista

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Posted 16 March 2019 - 12:51 PM

It seems my ASI071 may have an issue. I've not noticed this before...however I have mostly used the camera for lunar imaging. I think the sensor must have become damaged somehow, not sure how, but I have two obvious artifacts in all frames, including dark frames:

 

Master Bias (definitely no light leaks):

O40wmWm.jpg

 

Master Flat (note the dark arc in the center is now a light arc...???):

ZIt7xpL.jpg

 

Integrated Lights (not calibrated or aligned...large light spot is there, no arc???):

bSX1sIQ.jpg

 

Anyone ever experienced anything like this before?



#2 happylimpet

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Posted 16 March 2019 - 12:55 PM

So, if Jon Rista was replying to this thread, I'm sure he'd ask if they calibrate out fine?!

 

I have some odd little patches of pixels on my ASI1600MM but thay all seem to calibrate out fine. The circle is particularly odd though. Maybe a patch of the crystal with slightly different doping, or something?



#3 Jon Rista

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Posted 16 March 2019 - 01:02 PM

So, if Jon Rista was replying to this thread, I'm sure he'd ask if they calibrate out fine?!

 

I have some odd little patches of pixels on my ASI1600MM but thay all seem to calibrate out fine. The circle is particularly odd though. Maybe a patch of the crystal with slightly different doping, or something?

The large spot seems to calibrate out, but the arc in the center does not. There seem to be some other slight issues as well once the frame is calibrated (a gradient line at the top of the frame). The calibrated flat frames still have the arc. Problem is, the arc is dark in the biases, light in the flats, so the biases don't affect the arc at all when they are subtracted from the flats. Since the arc is in the flats and not in the lights, the arc then APPEARS in the lights.

 

Apparently in all my fiddling last night, I affected some of the dust motes, so the calibration is not perfect in general, so there are remnant motes and such throughout the calibrated lights. I'm currently working on fully calibrating, registering and integrating everything properly to see what the final result looks like.



#4 Jon Rista

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Posted 16 March 2019 - 02:38 PM

The camera pretty much seems to be a bust for DSO. It doesn't calibrate properly. The spot appears in all frames, but subtracting those frames doesn't seem to correct it in others. I think it is because the relative intensity scales with the signal, so it is very very faint in a bias, but in relative terms above the biase floor it is about the same relative intensity as the intensity of the spot above the mean level of a flat when in a flat. The arc signal seems to respond to light and scale in an entirely different way than all the other pixels in the sensor. At more medium signal levels, the arc balances out with the other signal levels, which is probably why I haven't seen it in lunar images. And since I don't calibrate lunar images, I've never run into the problem before. But it seems it is generally a bust for DSO, and always has been. I just didn't know why before...

 

Well, I'm working on getting the ASI1600 working with the FSQ106 for tonight. Hopefully there won't be any data issues with that setup.


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#5 calypsob

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Posted 16 March 2019 - 03:49 PM

That’s a weird issue and if it’s in your dark frames I would just contact Zwo. Sounds like they need to do a repair

#6 numchuck

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Posted 16 March 2019 - 04:00 PM

Is it a coincidence that the arc and the spot would appear to have a similar radius ?



#7 Jon Rista

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Posted 16 March 2019 - 05:52 PM

That’s a weird issue and if it’s in your dark frames I would just contact Zwo. Sounds like they need to do a repair

I contacted them earlier. Sounds like they will look into the issue on monday.

 

 

Is it a coincidence that the arc and the spot would appear to have a similar radius ?

I am not sure. I've never seen anything like this before...maybe the spot and the arc are related...



#8 entilza

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Posted 16 March 2019 - 08:24 PM

Hey Jon good luck with your new 106!

Seeing those artifacts in the bias and darks would definitely have me concerned. Lets see what ZWO says. I doubt others have this.. The question is how can it get damaged?


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