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I am having an issue that I am hoping for help here. I take astro pictures using: Nikon D850 with a Sigma 14mm F1.8 Dg ART lens on a tripod. I usually take a 6-10 images of the the night sky and denoise with a stack in starry landscape stacker (SLS). Every once is a while after stacking in SLS I end up with a photo with grainy ridges and rings. Any idea what could be causing this? The exposure here is ISO 6400 for 13 seconds at F1.8.

Rings in photo bottom left is the most clear

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  • \$\begingroup\$ Some possibilities: What causes faint circles in astrophotography images? / What is the “Newton Effect”? / What causes and how can I avoid this moiré pattern in a composite night sky photograph? \$\endgroup\$
    – xiota
    Aug 18, 2020 at 6:38
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    \$\begingroup\$ Does the software perform lens correction before stacking? Is there any improvement if you turn it off? \$\endgroup\$
    – xiota
    Aug 18, 2020 at 6:40
  • \$\begingroup\$ On a hunch... I wondered if the source files were RAW. I checked the software site and found that RAW files aren't supported. This makes me wonder if white-balance issues occurred during conversion and not all frames had a common white balance. You might explore your source data. \$\endgroup\$
    – Tim Campbell
    Aug 18, 2020 at 13:37
  • \$\begingroup\$ Thanks, Xiota - the software does not perform lens correction. Will take a look at the links you provide. \$\endgroup\$
    – pce_photo
    Aug 18, 2020 at 13:37
  • \$\begingroup\$ Thanks, Tim - I have to convert to tiff first. \$\endgroup\$
    – pce_photo
    Aug 18, 2020 at 13:39

2 Answers 2

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Are you sure you're setting White Balance manually? I think this may be related to differences in Auto White Balance color temperature between the shots.

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  • \$\begingroup\$ This makes total sense, thank you. I experimented with temps around 4200 and I does not happen. It could very well be the auto white balance. Will check out again this week. Thank you! \$\endgroup\$
    – pce_photo
    Aug 20, 2020 at 0:29
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This could be, as already pointed out, effects triggered by the initial processing of the images.

The web site has instructions for how they should be pre-processed before loaded into SLS:

https://sites.google.com/site/starrylandscapestacker/preparing-images-for-starry-landscape-stacker

In summary, they are:

  • reduce the contrast
  • turn off sharpening and noise reduction
  • apply lens chromatic aberration corrections - but turn off all other lens corrections
  • Set custom white balance
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  • \$\begingroup\$ Thanks Pete - this was the fix \$\endgroup\$
    – pce_photo
    Sep 20, 2020 at 6:29

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