ZWO vs Astronomik NB filters

[kosborn]

Hi all,

I purchased ZWO filters (LRGB, Ha, OIII and SII) with an 8 position ZWO filter wheel last year. This has worked well with my ASI1600mm camera except that the narrowband filters produce strong reflections around bright stars as the attached picture shows (compared to the LRGB filters). I was careful to orientate the filters the correct way when I installed them so I'm pretty sure the problem is with the filters. I've certainly read of similar issues on various forums.

I'm wondering if anyone has experience with the Astronomik 6nm filters, especially combined with the ASI1600mm?

Thanks, Kevin

[The_bluester]

I have an OSC camera bit I recall seeing “new” ZWO filters that are supposed to resolve exactly that issue.

[Atmos]

Although Glen is correct with the ASI1600 microlens issue which is visible in the Lum sub, the reflections in the Ha are entirely different and a filter issue.

Paul is correct in that ZWO agave released some new narrowband filters with better coatings. Not sure how the new ZWO filters compare to the Astronomik ones but either of them is going to produce less reflections than your current narrowband set.

[codemonkey]

I've got the Astronomik 6nm narrowband set and used to have the ASI1600MM-C. I never saw halos like that and have been very happy with my set.

All the below images were taken with the ASI1600MM-C, Astronomik SII and OIII where applicable.

These two used a Baader Ha:

https://www.astrobin.com/272385
https://www.astrobin.com/260551

These two had the Astronomik Ha:

https://www.astrobin.com/291734
https://www.astrobin.com/283343

Pretty sure I saw a thread on cloudynights that reviewed the new ZWO filters and if I recall correctly they were better, but OIII still had halo issues. I could be wrong on this though, I had no interest in buying the filters and simply saw it in passing. I encourage you to search the "CCD/CMOS Astro Camera Imaging & Processing" section to try and find that thread.

[kosborn]

Thanks guys.

I've trolled through Astrobin and found very few Astronomik/ASI1600 combinatinations, none of which show rings. Many more Astrodon/ASI1600 combinations, also none of which show rings. Astrodon is probably too expensive but Astronomik looks like a good alternative. Not sure I'd risk the new ZWO ones, just in case...

By the way Lee, very nice Trifid. Certainly deserved IOTD!


Kevin

[AstroApprentice]

Do you have filter rings installed? If not, contact ZWO and they will provide them for free. They help reduce internal reflections - there’s a thread on CN about them. Perhaps try that first as it won’t cost you anything except a week or so waiting for post.

[kosborn]

Yes, I have the filter rings installed (they came with the filters). I found this interesting comparison (https://www.cloudynights.com/topic/605371-comparing-zwo-vs-astrodon-36mm-filters-a-controlled-test/) on CloudyNights directly comparing Astrodon and ZWO filters. The halos weren't present on the Astrodon filters. I wish I could find a similar Astronomik/ZWO comparison.

[Russj]

I've been using Astronomik 6nm nb filters with the ASI1600mm pro and not had any problems with them.

[kosborn]

Thanks Russ, that's good info.

[Camelopardalis]

I use Astronomik filters LRGB/HaOIIISII and have never noticed any halos with my ASI1600, FWIW.

[kosborn]

Thanks Dunk. I think I'll jump in head first with the Astronomik Ha filter (Ha is the worst of the ZWO filters). And all being well I'll add OIII and SII.