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SII filter recomendation

Filters Imaging Optics Astrophotography
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#1 yeclek

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Posted 08 December 2023 - 01:21 AM

Hello everyone!

 

I'm looking for suggestions for a good SII filter. I'm currently using an Optolong 6.5nm SII 1.25" mounted filter. However, as you can see in the image below, it suffers from fairly bad halos. The Ha and Oiii filters from this set work fine though, with minimal halos. This has been a real pain for processing, and I still don't have a great process for removing them. 

 

I know that certain setups can have more issues than others but I'm hoping someone here has something similar or can suggest a different filter. Hopefully in the same-ish price range, $200-$300. I have an ASI 294MM attached to an EFW and a Astro-tech reducer on a 102mm scope. 

 

Also, if anyone has suggestions on techniques for removal of these halos I would greatly appreciate the knowledge!

 

 

 

Thanks in advance for your help!

Kelcey

 

 

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#2 Paul Puntin

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Posted 08 December 2023 - 11:25 AM

I can vouch for the Astronomik Sii 6nm filter. It’s halo free and in your budget. It’s also nearly the same bandwidth as the Optolong, so should match up pretty well with the other two. My Baader Sii filter gives pretty bad halo’s, so one to avoid.

 

To remove the halo, I tend to remove the stars (Starnett or StarExterminator) and then use clonestamp in Pixinsight or healing brush or similar in Photoshop to erase the halo from the starless image. Then just add your stars back. There are a number of other techniques if you do a search on google including YouTube tutorials.


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#3 rgsalinger

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Posted 08 December 2023 - 12:10 PM

I would expect that if you get any other brand of filter, you need to be prepared for it NOT to be par focal with your existing filters. I'm not sure why you are getting those halos though. I have the same SII filter on my Edge 11 HD and don't get them. Other than those caveats, I completely agree with the previous poster that Astronomik's are a very good choice. 

 

Rgrds-Ross



#4 yeclek

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Posted 08 December 2023 - 03:37 PM

Thanks Paul. I'll take a look at the Astronomik.

 

Cloning is my current method for halo removal but it only really works well in areas without much nebulosity. Otherwise, it's pretty time consuming. That's why I'd like to just not have them at all in the first place. wink.gif  



#5 yeclek

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Posted 08 December 2023 - 03:40 PM

Thanks Ross!

 

Another vote for Astronomik! 

 

I'm not too concerned about them being parfocal. Even though the Optolongs came in a set they aren't perfectly parfocal and I need to run an autofocus routine on each filter change any way. Or rather it's probably the issue that my cheap doublet doesn't focus each wavelength at the same point. 




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