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16 bit from Deep Sky Stacker? Calibration issues.

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#1 Simon D.

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Posted 24 January 2020 - 12:04 PM

I’m having issues with calibration frames in my final image of Pleiades.  There’s a fixed pattern (you can see it on the right) that should have been removed with my bias, darks, and flats.   This Is from an unmodded Canon 5D IV.  I exported the raws (CR2) from Lightroom into a folder, and open them on DSS from there (Lights, darks, bias, flats). I’m processing in Photoshop.   This is the same workflow I’ve used before with no issues.  Also, the final image from stacking is coming out 115 MB 16 bit TIFF, where in the past it was much higher 347 MB and higher bit depth. I would convert to 16 bit in Photoshop, but now it starts at 16.  I’m not sure these two issues are related, but sharing these issues in case related. I have less than an hour of data, which I know affects the image quality. 

 

Any ideas what might be causing this?

 

 

Attached Thumbnails

  • Pleiades small (1 of 1).jpg

Edited by Simon D., 24 January 2020 - 12:11 PM.


#2 Simon D.

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Posted 24 January 2020 - 12:12 PM

I've figured out the 16 bit problem, but my image still looks the same.  Is there something wrong with my calibration frames?  Flats taken at same ISO and middle of the historgram...darks at same temp, duration and ISO...bias at 1/8000 and same ISO.


Edited by Simon D., 24 January 2020 - 01:17 PM.


#3 einarin

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Posted 24 January 2020 - 12:21 PM

So you get better end result now ?



#4 sharkmelley

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Posted 24 January 2020 - 12:25 PM

Sorry I may have tracked this down...the save settings from DSS was changed to 16 bit somehow

I hope you've solved it but I'm not convinced that 16 bit would cause those artefacts.  

 

Mark



#5 Simon D.

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Posted 24 January 2020 - 01:54 PM

So you get better end result now ?

 

 

I hope you've solved it but I'm not convinced that 16 bit would cause those artefacts.  

 

Mark

 

No I still have the same.  Here are two pics...one is a single dark frame, raised 5 stops in Lightroom and added a bit of white, showing the pattern noise.  The second dark is my master dark, exposure raised the same amount.  Its almost black...while I realize its going to be dark, shouldn't it be at a similar exposure level to a single dark frame?

 

What stacking settings should I be using for darks?  Average or mean?

Attached Thumbnails

  • sinlge dark small (1 of 1).jpg
  • Master Dark lightened (1 of 1)-2.jpg

Edited by Simon D., 24 January 2020 - 01:59 PM.


#6 einarin

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Posted 24 January 2020 - 02:00 PM

The defaults in DSS should be fine.



#7 sharkmelley

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Posted 24 January 2020 - 02:47 PM

So the banding is almost certainly the infamous Canon banding.  What ISO were you using?

 

The darks may or not remove the bands with proper calibration but you are not achieving proper calibration because the files exported from LightRoom are non-linear.

 

You are better off loading the raw CR2 files into DSS.

 

Mark



#8 t-ara-fan

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Posted 24 January 2020 - 03:32 PM

The second dark is my master dark, exposure raised the same amount.  Its almost black...while I realize its going to be dark, shouldn't it be at a similar exposure level to a single dark frame?

 

 

The master dark should have some noise and fixed patterns on it, plus hot pixels. Totally black doesn't sound right.
 



#9 Simon D.

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Posted 24 January 2020 - 03:53 PM

So the banding is almost certainly the infamous Canon banding.  What ISO were you using?

 

The darks may or not remove the bands with proper calibration but you are not achieving proper calibration because the files exported from LightRoom are non-linear.

 

You are better off loading the raw CR2 files into DSS.

 

Mark

Thanks Mark.  ISO 800.  I thought the same thing and tried that, but to no avail.


Edited by Simon D., 24 January 2020 - 03:54 PM.


#10 Simon D.

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Posted 24 January 2020 - 04:08 PM

The master dark should have some noise and fixed patterns on it, plus hot pixels. Totally black doesn't sound right.
 

There seem to be a few not pixels, but that’s it. 



#11 Simon D.

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Posted 24 January 2020 - 04:10 PM

So the banding is almost certainly the infamous Canon banding.  What ISO were you using?

 

The darks may or not remove the bands with proper calibration but you are not achieving proper calibration because the files exported from LightRoom are non-linear.

 

You are better off loading the raw CR2 files into DSS.

 

Mark

I got this using the same iso and settings a few weeks ago.  With calibration frames it’s clean and flat, so I’m stumped. 

Attached Thumbnails

  • C3721125-8FD5-4EBE-ABE3-822619EE2768.jpeg



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