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(@ajm16143)
White Dwarf Customer
Joined: 7 months ago
Posts: 13
January 16, 2021 15:54  

Hi everyone, I just finished a two-night session on the flame and horsehead nebulae with my astro-modded Rebel T6.  The top two-thirds of the image look pretty decent, but then I have this hard gradient and what looks like the program choked in a few areas.  Does anyone have any idea what causes this?  I'm currently re-running the set with a lower degree LNS (only thing I changed from my usual process) but don't have the new result yet.

Flame and Horsehead

 


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(@wvreeven)
Galaxy Admin
Joined: 2 years ago
Posts: 593
January 16, 2021 17:29  

@ajm16143 We would need to know more about how you process the images to be able to help you solve this. What OS are you on? What version of APP? Are you processing the images on the local hard disk or an external one? Does it help if you disable OpenGL in the APP settings?


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(@ajm16143)
White Dwarf Customer
Joined: 7 months ago
Posts: 13
January 16, 2021 19:13  

@wvreeven I'm using Windows 10, APP 1.082, and processing on a local drive. I just reprocessed the data and it seems that the problem is in my first session as the second looks fine. I'll try disabling OpenGL on them and see what happens.


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(@ajm16143)
White Dwarf Customer
Joined: 7 months ago
Posts: 13
January 17, 2021 02:46  

@wvreeven Disabling OpenGL didn't do anything to help.  I ran the first set of lights without any calibration frames and the red bands show up, so it must be something in the lights.  I checked all of them in APP and don't see anything strange in any individual frame.    


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(@wvreeven)
Galaxy Admin
Joined: 2 years ago
Posts: 593
January 17, 2021 13:20  

@ajm16143 Can you upload a small sample of your lights and calibration files to

https://upload.astropixelprocessor.com/

using username and password upload2 and create a directory there called ajm16143_artifacts with the files in there? Then we can have a look and see if we can find the cause. Thanks!


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(@ajm16143)
White Dwarf Customer
Joined: 7 months ago
Posts: 13
January 17, 2021 17:02  

@wvreeven Thank you, I uploaded them as instructed.  What's interesting is I ran the same files through Deep Sky Stacker and don't see the artifacts so not sure what I did that's introducing them in APP.


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(@wvreeven)
Galaxy Admin
Joined: 2 years ago
Posts: 593
January 17, 2021 19:18  

I loaded the Lights, Flats, Darks and DarkFlats in tab 1 and then went straight to tab 6 and clicked the Integrate button. Everything else I left at their defaults. The result is this:

Screenshot 2021 01 17 at 19.08.29

 

A few comments: I see that your Flats and DarkFlats are 0.3 second exposures. With a DSLR camera you should take Flats of at least 1 second to give the shutter enough time to open and close because otherwise you run the risk of getting the shadow of the shutter in your Flats which will introduce other artifacts which will be hard to get rid of.

Also, your Bias and DarkFlats have the same exposure time. When Bias correction is applied, the effect of the DarkFlats will be reduced to zero, which may very well be the cause of the issue.

So, next time make sure to take longer Flats. If necessary dim the light source that you use to take them or, if that's not possible, use a white t-shirt or blanket over the opening of the telescope to dim the light. Also, either take very short Bias exposures or leave them out all together.


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(@ajm16143)
White Dwarf Customer
Joined: 7 months ago
Posts: 13
January 17, 2021 19:41  

@wvreeven Thank you for testing that.  Not sure what setting I did that aggravated it, but glad to know the data is good.

I think the bias issue was a mistake on my part uploading, they should have been 1/4000 shutter speed as that's what all the ones in my computer were shot at, but I think I mistakenly uploaded the dark flats to both folders.  I will definitely take your advice on longer flats.  


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