Author Topic: Bright star halos  (Read 1914 times)

Offline sreilly

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Bright star halos
« on: 2014 September 22 14:16:12 »
I have noticed that I get halos around my brightest stars when doing HDRWavelet processing. I do use a mask most times or sometimes use the "Lightness Mask" option instead. What seems to happen, in this particular case of IC1396A (The Elephant Trunk Nebula) several of the brightest stars really get fuzzy edges, halo like. What do I need to do to resolve this. I did try using more aggressive settings for the star mask but with mixed results. In particular are two pairs of close stars. I've posted the image in question for download should you care to try at .

http://endor.uv.es/files/data/public/532829.php

The uploaded image is a combination of 14 fifteen minute luminance images taken with my 12.5" f/9 OGS RC and STL-11002M using Baader filters. The images were calibrated, cosmetically corrected, aligned, combine, cropped, had ABE process used, then masked stretched and saved. I'm hoping to get some better data to work with the next few nights.

Thanks for any insight.

-Steve
Steve
www.astral-imaging.com
AP1200
OGS 12.5" RC
Tak FSQ-106ED
ST10XME/CFW8/AO8
STL-11000M/FW8/AO-L
Pyxis 3" Rotator
Baader LRGBHa Filters
PixInsight/MaxIm/ACP/Registar/Mira AP/PS CS5

Offline sreilly

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Re: Bright star halos
« Reply #1 on: 2014 September 22 14:22:10 »
What I have gotten so far with my RGB and luminance data can be seen here http://www.astral-imaging.com/IC1396A-RC2.html
Steve
www.astral-imaging.com
AP1200
OGS 12.5" RC
Tak FSQ-106ED
ST10XME/CFW8/AO8
STL-11000M/FW8/AO-L
Pyxis 3" Rotator
Baader LRGBHa Filters
PixInsight/MaxIm/ACP/Registar/Mira AP/PS CS5

Offline RickS

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Re: Bright star halos
« Reply #2 on: 2014 September 22 14:54:59 »
I always build a mask that protects the background and also the stars before I apply HDRMT or LHE.

Cheers,
Rick.

Offline sreilly

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Re: Bright star halos
« Reply #3 on: 2014 September 22 16:53:12 »
Care to share your technique?
Steve
www.astral-imaging.com
AP1200
OGS 12.5" RC
Tak FSQ-106ED
ST10XME/CFW8/AO8
STL-11000M/FW8/AO-L
Pyxis 3" Rotator
Baader LRGBHa Filters
PixInsight/MaxIm/ACP/Registar/Mira AP/PS CS5

Offline RickS

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Re: Bright star halos
« Reply #4 on: 2014 September 22 17:19:13 »
Care to share your technique?

I usually just start with a black clipped luminance mask, then remove the stars [something like PixelMath: iif(star_mask>0.1,0,lum_mask)] followed by a small blur to get rid of the sharp edges on the stars.  You can adjust the 0.1 number depending on how good a fit your star mask is.  Another option is PixelMath: lum_mask*~star_mask.

Cheers,
Rick.