NII processing

[Rodd]

This is more of a question pertaining to processing as opposed to software.  My question is..Astrodons 3nm Ha filter does not include NII emissions, where as the Baader 7nm Ha filter does.  But I like the Astrodon 3nm Ha emissions better than the Baader.  Would it be possible to subtract a Astrodon 3nm Ha image from a Baader 7nm Ha image and be left with NII emissions?  Then I could add the NII data to teh Astrodon 3nm data and have teh best of both worlds.  I ask this because Astrodon does not make a 36mm NII fiilter (the size I need for my filter wheel).

 

Thanks---Rodd

[ChrisLX200]

You may as well just use the Baader 7nM if you want to do that, because by adding back the NII you would lost the tiny star profile and high contrast that the Astrodon 3nM is giving you.

ChrisH

[Rodd]

6 minutes ago, ChrisLX200 said:

You may as well just use the Baader 7nM if you want to do that, because by adding back the NII you would lost the tiny star profile and high contrast that the Astrodon 3nM is giving you.

ChrisH

Yes but the only difference between the Ast. and Baa,  is not only the NII emiision lines.  The Ha emissions are at 3nm with the Ast. while they are at 7nm with the Baa.  the NII just happens to be there as well.  Besides, it would allow the separate processing of the NII.  Astrodon does make a NII filter in 1.25".  If there wasn't a difference why would they make the filter and not just say "use the 7nm?" I am just curious.

[ChrisLX200]

Just now, Rodd said:

Yes but the only difference between the Ast. and Baa,  is not only the NII emiision lines.  The Ha emissions are at 3nm with the Ast. while they are at 7nm with the Baa.  the NII just happens to be there as well.  Besides, it would allow the separate processing of the NII.  Astrodon does make a NII filter in 1.25".  If there wasn't a difference why would they make the filter and not just say "use the 7nm?" I am just curious.

Because you might actually want just the NII? Some folk do bi-colour Ha/NII imaging.

ChrisH

[Rodd]

18 minutes ago, ChrisLX200 said:

Because you might actually want just the NII? Some folk do bi-colour Ha/NII imaging.

ChrisH

Speaking of filters.  I got teh 3nmHa and the 3nm OIII--do you think I should 

a) use my Baader 8.5nm SII

get a 5nm SII Astrodon

c) get the 3nm SII Astrodon?

[ChrisLX200]

Personally, I use a 3nM SII, but seeing as you already have the Baader then give it a try - monitor the star diameters to ensure there isn't a big difference (otherwise all your stars will end up with a halo)

ChrisH

[Gina]

You might be able to remove the stars from the Baader SII image using a star mask.

[Rodd]

On 8/13/2016 at 15:47, ChrisLX200 said:

Personally, I use a 3nM SII, but seeing as you already have the Baader then give it a try - monitor the star diameters to ensure there isn't a big difference (otherwise all your stars will end up with a halo)

ChrisH

On 8/13/2016 at 15:54, Gina said:

You might be able to remove the stars from the Baader SII image using a star mask.

If buying the Astrodon S11 filter will prevent halos, then that is what I'll do.  As far as I am concerned, anything I can do to avoid additional processing the better.  I am almost to the point of just shooting Ha anyway.  Anything else is a huge waste of my time and message board space.