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Reflections galore. Filter or something else?

Acquisition SHO Narrowband Deep Sky
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Ashraf AbuSara avatar
Ashraf AbuSara avatar
Setup is:
AG Optical Convergent FA12 
6200mm pro
Chroma Ha 8nm, Oiii 5nm, Sii 5nm 50mm round unmounted filters.
Telescope Express 3" focuser. 
ZWO EFW
Zwo OAG-L

This was 2 hours for each filter (Ha / Oiii / Sii) on the Jellyfish.  The mirror surface of the filters is pointing away from the camera sensor towards the telescope. Propus  wreaked absolute havoc on the image. Reflections everywhere in the Ha and Sii frame. Not very noticable in the Oiii frame. Any suggestions what could be causing this?

Ha:


Oiii:


Sii:
Helpful
andrea tasselli avatar
andrea tasselli avatar
Usually, it's filters. The culprit: Eta Geminorum. Having said that, your configuration is a tad exotic so I wouldn't discount the corrector as yet. I don't have the originals but you can easily figure out the out-of-focus distance from the size of the exit pupil diameter (the reflections) once expressed in mm/inch.
Brian Boyle avatar
Brian Boyle avatar
Hi Ashraf,

You have the same problem as I did.

Problem identified and I used a somewhat unconventional way to fix it.  

CS Brian


https://www.astrobin.com/forum/c/astrophotography/deep-sky/unusual-ghosting-pattern/
Ashraf AbuSara avatar
Ashraf AbuSara avatar
andrea tasselli:
Usually, it's filters. The culprit: Eta Geminorum. Having said that, your configuration is a tad exotic so I wouldn't discount the corrector as yet. I don't have the originals but you can easily figure out the out-of-focus distance from the size of the exit pupil diameter (the reflections) once expressed in mm/inch.

That's what I was afraid off, thanks Andrea. So basically no hardware fix really. Just have to deal with it in post processing.
Brian Boyle:
Hi Ashraf,

You have the same problem as I did.

Problem identified and I used a somewhat unconventional way to fix it.  

CS Brian


https://www.astrobin.com/forum/c/astrophotography/deep-sky/unusual-ghosting-pattern/

Thanks for the link Brian! I guess I won't try to go crazy at this point knowing there really is no hardware fix. 

I already sort of processed the image in Pixinsight and I managed to mostly get rid of them, but I will definitely try that link and see if I can get a better result.

Brian Boyle avatar
Brian Boyle avatar
Hi Arjun,

I think you did a great job.  And I agree you just sometimes have to accept that sometimes bright stars photobomb DSOs. 

Or to paraphrase a famous engineer:  "you canna change the laws of physics"

CS Brian
Ashraf AbuSara avatar
Ashraf AbuSara avatar
Brian Boyle:
Hi Arjun,

I think you did a great job.  And I agree you just sometimes have to accept that sometimes bright stars photobomb DSOs. 

Or to paraphrase a famous engineer:  "you canna change the laws of physics"

CS Brian

Thanks so much Brian.

CS!

Ashraf