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Old 20-05-2015, 06:17 PM
Tony_ (Tony)
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Help needed

I seem to get colour abberations in my images like the one in this image.
It seems to be in the same direction regardless of the camera orientation to the scope or actual position, so I am not sure about the cause being telescope optics? My collimation was very good.

My set up in this image:
SCT 9.25" with f/6.3 reducer. Canon CDS 60d at -13C
about 80 x 30sec subs stacked with DSS and processed with photoshop.

At one stage I suspected that my corrector plate is out of alignment - but the orientation of the abberation would change with camera rotation.

Does anyone have any ideas what it could be and how to fix it??

Regards,
Tony.
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  #2  
Old 20-05-2015, 06:41 PM
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Merlin66 (Ken)
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At what altitude were you imaging?
Looks like it could be atmospheric chromatic aberrations....
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Old 20-05-2015, 07:05 PM
Tony_ (Tony)
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Altitude was around 80 degrees - not far from overhead.

Tony.
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Old 20-05-2015, 09:23 PM
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Moon (James)
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What happens when you take an image without the reducer?
James
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Old 20-05-2015, 10:00 PM
Tony_ (Tony)
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Thanks for your replies.

It seems worse with the reducer. Sometimes it is only slightly visible (without the reducer). Actually looking at a few more images it isn't always in the same configuration and it isn't always as bad.
I have removed the corrector plate a few times. The first time I didn't take note of the spacers. I think it is in the right rotational position but probably not in the correct alignment position. I wonder if this could cause this effect?
I will have to do some more trials with the position of the camera and see if I can determine if it is a specific direction.

Tony.
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Old 20-05-2015, 10:32 PM
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alpal
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Quote:
Originally Posted by Tony_ View Post
Thanks for your replies.

It seems worse with the reducer. Sometimes it is only slightly visible (without the reducer). Actually looking at a few more images it isn't always in the same configuration and it isn't always as bad.
I have removed the corrector plate a few times. The first time I didn't take note of the spacers. I think it is in the right rotational position but probably not in the correct alignment position. I wonder if this could cause this effect?
I will have to do some more trials with the position of the camera and see if I can determine if it is a specific direction.

Tony.

I am taking a stab in the dark:

Have you tried to debayer the DSLR RAW frames during stacking?
I doubt this problem you are seeing would happen with a mono camera.

cheers
Allan
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