2026: best dual-narrowband filters for RASA 11?

Celestron RASA 11"
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John Stone avatar
John Stone avatar
There's been a lot of new development in filter tech over the last 2-3 years.

I'm looking to buy a RASA11 with a IMX571 camera and am looking for dual-narrowband filters.

I'm looking for the tightest bandpass, most transmission, and least halo experience possible.

Cost is not a large consideration.

So, what's the consensus for filters like these in 2026?
Well Written Engaging
andrea tasselli avatar
andrea tasselli avatar
There is only one game in town: Antlia. 5nm variety for you. And for me too.
John Stone avatar
John Stone avatar
Do you mean the Antlia ALP-T Dual Band 5nm Ha&OIII Highspeed Filter? 

http://www.antliafilter.com/pd.jsp?fromColId=120&id=126#_pp=120_571

Does anyone know of a Sii/Oiii filter like this?

Has anyone ever tried the Askar D1 series (or other 6nm - 7nm bandpass) dual narrowband filters?

Thanks.
andrea tasselli avatar
andrea tasselli avatar
There are no GOOD high speed versions of DNB filters other than that. You can couple it with the ANTLIA SII+Hb and you'd get 4 channels with two filters. Performance at the OIII wavelength for the Askar D1 is somewhat luck-luster @ f/4 and I can't imagine what it would be like  at f/2.2 coupled with a largish CO. Ditto for the D2 filter.
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