Bloated stars

Comments

• Michael J Benson

  October 2022

  I think the problem is both the filter and the focus.  As the night wore on, the temperature dropped and you did not refocus.  I think you should refocus every hour or so as the temperature drops.  Also there are comments on the web about the filter causing some bloating and halo of stars.  Looking at your pics I would say it is probably more halo than bloating.  Glad to help where I can.  Good luck on trials.  Hey, that’s me answering my own dumb question.
• Ken Bates

  October 2022

  I have the same issue with an L-Extreme filter. The problem is the very large halo, which has multiple "rings". I've tried numerous methods, including PixelMath that attempts to separate the halo from the background and then subtract the halo, and/or localized masks (GAME script) to isolate and process the halo, to name a few. All are moderately successful,  but still leave obvious artifacts. I think problem is partially due to the filter, and I believe that mono cameras may have the same issue with O3 filters, albeit to a lesser degree. A typical image is attached showing the problem. Just very basic preprocessing and a simple stretch (slightly cropped) to show the problem. Note: focusing should not have an issue; I autofocus every 2 degree change in temperature and/or 10% change in HFR.

  
  

  So, are there any processing steps that come to mind that can fix this issue? It's definitely a very bright star and I can live with that, but the large, multi-level halo is really obnoxious and I would like to eliminate it if possible. Any ideas on what to try?

  
  

   - Ken

  
  

  

  

  halo.jpg

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• Michael J Benson

  November 2022

  Thanks Ken.  I have tried a number of methods, but they all leave artifacts.  I've reshot the Pleaides without the filter and it is perfect.