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Old 07-04-2021, 02:22 PM
MarkInSpace (Mark)
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What causes the coloured star fringes?

What causes my stars to have coloured star fringes - blue on the upper right, red on the lower left?
Is this caused by the atmosphere or the telescope?
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Old 07-04-2021, 02:29 PM
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multiweb (Marc)
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It can be both. Every telescope has some degree of chromatic aberration. The sensor used can also make it worse so does your image scale. For example if you use an OSC with a bayer matrix the debayering process direct to color might cause edges color artefact. That can be worked around by debayering to individual channels then recombining. What you're showing in your picture is very minimal to my eyes. Don't fret too much about it.
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Old 07-04-2021, 03:18 PM
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That (lateral Chromatic Aberration, CA) can be sorted out with software.. PtLens, for example.
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Old 07-04-2021, 05:21 PM
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If you have a good quality eyepiece you can test your chromatic aberration on a bright star or the moon. The edge of the moon is a very harsh test of this.

Greg.
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Old 07-04-2021, 07:38 PM
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mswhin63 (Malcolm)
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Quote:
Originally Posted by MarkInSpace View Post
What causes my stars to have coloured star fringes - blue on the upper right, red on the lower left?
Is this caused by the atmosphere or the telescope?
I was just about to post something on the same lines. Thanks for placing it in first.
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Old 08-04-2021, 12:01 AM
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Joshua Bunn (Joshua)
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Also if you are using a mono camera, this can arise if your RGB stack was not perfectly aligned when creating the colour image.
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Old 08-04-2021, 02:43 AM
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billdan (Bill)
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Ivo from Startools suggests its a stacking artefact (I asked him the same question 3 years ago).
Startools does have a process/module that fixes it. Basically moving the red or blue pixels slightly (left/right/up/down).
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Old 10-04-2021, 01:20 PM
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mswhin63 (Malcolm)
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Quote:
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Ivo from Startools suggests its a stacking artefact (I asked him the same question 3 years ago).
Startools does have a process/module that fixes it. Basically moving the red or blue pixels slightly (left/right/up/down).
Do you know what Module, I can't locate it unless it is called something that I use for different reasons?
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Old 12-04-2021, 02:12 PM
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billdan (Bill)
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Sorry for the late reply Malcolm.

It's in the Lens module, at the bottom are some sliders labelled blue shift (X or Y) and red shift (X or Y).
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