PixInsight Forum

PixInsight => Tutorials and Processing Examples => Tips & Tricks => Topic started by: Lex on 2018 June 03 00:02:27

Title: Odd Diffraction Spikes
Post by: Lex on 2018 June 03 00:02:27
Hi all,

in all of my subs there are doubled diffraction patterns, strangely they are not evenly distributed over the image.
Image was captured with SGP and Autofocus routine was always ok. Collimation was on spot too; at least IMO  ;D

Here is an integration of 10*300s ZWO R filter, ASI1600mm-c, 10" f/5 Newt, Baader MPCC-Miii, PHD2 guiding was good.

http://endor.uv.es/files/?goto=forum-shared-files%2FLex%2FIC1396_Red.tif (http://endor.uv.es/files/?goto=forum-shared-files%2FLex%2FIC1396_Red.tif)

Before I begin disassembling again and doing unnecessary stuff I prefer to ask the pros in here!

Very Best & CS,

Lex
Title: Re: Odd Diffraction Spikes
Post by: bulrichl on 2018 June 03 01:10:33
I don't get access to your image.

Bernd
Title: Re: Odd Diffraction Spikes
Post by: sreilly on 2018 June 03 04:53:47
The only way to see this image is to download form a service that requires a login. I don't think many people will join to download an image. If you have  away to post with a shared service it would be better.

-Steve
Title: Re: Odd Diffraction Spikes
Post by: Lex on 2018 June 03 08:02:09
Hi;

Sorry for that, tought that mor people would have an access there.
Here is the DB link:

https://www.dropbox.com/s/u46kbyuoajq37zu/IC1396_Red.fit?dl=0 (https://www.dropbox.com/s/u46kbyuoajq37zu/IC1396_Red.fit?dl=0)

Does it work?

Best!

Lex
Title: Re: Odd Diffraction Spikes
Post by: msmythers on 2018 June 03 08:34:36
Lex

Have you used the Blink tool to look at the individual subs? My guess is your polar alignment is out if this is happening with all your subs. If it just the red then your filter may have some strange alignment issue or add reflection.



Mike
Title: Re: Odd Diffraction Spikes
Post by: Lex on 2018 June 03 08:36:20
The problem mainly appears in the middle of the image, even knowing that there is a close formation of two stars.
To the sides the double diffraction pattern is less noticeable, which is kind of strange.
If it is camera tilt, it should be worse on only one side?

 
Title: Re: Odd Diffraction Spikes
Post by: Lex on 2018 June 03 08:38:07
Hi Mike,

Thanks for your help! I will check with Blink. Why do you think it could be PA?
Title: Re: Odd Diffraction Spikes
Post by: Lex on 2018 June 03 09:01:38
Mike,

after checking Blink, it seems that there was a strange focus drift, some subs are fine, most of them are not.
My only concern is that not the whole images seem to be out of focus; this is why i think the image train is tilted.

Polar Alignment should be fine, i aligned my permanent setup one week ago.

What is driving me crazy is that it is the first fully automated session without problems; an then this....  >:(

Title: Re: Odd Diffraction Spikes
Post by: msmythers on 2018 June 03 09:39:29
Lex


You might want to look at this posting as a method to possibly remove the extra spikes.

https://pixinsight.com/forum/index.php?topic=9917 (https://pixinsight.com/forum/index.php?topic=9917)


Mike