D2 experience with fast optics (f/2.2)?

Askar ColourMagic D2 (Sii+Oiii) Duo Narrow Band 6nm 2" Filters Duo-Narrowband
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Is the d2 working well for you on a Hyperstar/rasa?
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Sjors Robroek avatar
Sjors Robroek avatar
Im looking for a sii/oiii dual narrowband filter specifically for a Hyperstar 9.25 v4, and unfortunately options are pretty slim. From the ones available it seems only the askar c2 and d2 are realistic, and the c2 seems to have a very wide bandpass. 

From the people using the d2 with a rasa/hyperstar, how has your experience been so far? The typical recommendation for filters seems to be a 10nm bandpass for filters which the d2 doesn’t meet, so I’m wondering how this filter is working out for you before I commit to it.
Engaging
Elevated_Astro avatar
Elevated_Astro avatar
I used the ZWO Dual band. I have a 9.25 and version 4 paired with an asi533. I believe I have a few examples in my public gallery but thought the pairing worked well.
andrea tasselli avatar
andrea tasselli avatar
Sjors Robroek:
Im looking for a sii/oiii dual narrowband filter specifically for a Hyperstar 9.25 v4, and unfortunately options are pretty slim. From the ones available it seems only the askar c2 and d2 are realistic, and the c2 seems to have a very wide bandpass. 

From the people using the d2 with a rasa/hyperstar, how has your experience been so far? The typical recommendation for filters seems to be a 10nm bandpass for filters which the d2 doesn’t meet, so I’m wondering how this filter is working out for you before I commit to it.

*I can't say about the SII/OIII one but the other one isn't doing too well at f/2.8. I suggest you consider the ALP-T Highspeed (as I do).
Sjors Robroek avatar
Sjors Robroek avatar
andrea tasselli:
Sjors Robroek:
Im looking for a sii/oiii dual narrowband filter specifically for a Hyperstar 9.25 v4, and unfortunately options are pretty slim. From the ones available it seems only the askar c2 and d2 are realistic, and the c2 seems to have a very wide bandpass. 

From the people using the d2 with a rasa/hyperstar, how has your experience been so far? The typical recommendation for filters seems to be a 10nm bandpass for filters which the d2 doesn’t meet, so I’m wondering how this filter is working out for you before I commit to it.

*I can't say about the SII/OIII one but the other one isn't doing too well at f/2.8. I suggest you consider the ALP-T Highspeed (as I do).

I’ve got the L-PARA for H/O but that’s good to know. Likely that the D2 might also not perform that well either.
David Néel avatar
David Néel avatar
I used the ZWO Dual band. I have a 9.25 and version 4 paired with an asi533. I believe I have a few examples in my public gallery but thought the pairing worked well.


ZWO Dual band is very large (15nm Ha and 35nm OIII). So it's fine for very fast optics.
Sjors Robroek avatar
Sjors Robroek avatar
David Néel:
I used the ZWO Dual band. I have a 9.25 and version 4 paired with an asi533. I believe I have a few examples in my public gallery but thought the pairing worked well.


ZWO Dual band is very large (15nm Ha and 35nm OIII). So it's fine for very fast optics.

That’s the H/O though, I’m specifically looking for the S/O dual narrowband.
Georg N. Nyman avatar
Georg N. Nyman avatar

I asked the manufacturer of those filters regarding the ability of the D series to work with my RASA and they responded, that they are fine with f /2.2

TiffsAndAstro avatar
TiffsAndAstro avatar
Georg N. Nyman:
I asked the manufacturer of those filters regarding the ability of the D series to work with my RASA and they responded, that they are fine with f /2.2

what is "fine" ?  
And how is it possible?
Georg N. Nyman avatar
Georg N. Nyman avatar

TiffsAndAstro · Aug 31, 2025, 11:34 AM

Georg N. Nyman:
I asked the manufacturer of those filters regarding the ability of the D series to work with my RASA and they responded, that they are fine with f /2.2


what is "fine" ?  
And how is it possible?

Fine means, that you can use them, their FWHM is large enough to work sufficiently well with f/2.2

How is it possible - if the bandwidth of the filter is not too small, the shift of the central wavelength does not matter or not matter much

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