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[Solved] How to add an IDAS NB3 filter to the mix?


(@devonshire)
Main Sequence Star Customer
Joined: 5 years ago
Posts: 33
Topic starter  

When the skies clear(!), I shoot mostly nebulas, with a modified Nikon D5300 and an L-Extreme filter. This gives me Ha + OIII. But my OIII is always weaker and noisier than my Ha, and I have no SII available.

So... I'm thinking of acquiring an IDAS NB3 filter, which (combined with the L-Extreme's data) will give me additional OIII signal, plus some SII.

What I'd like to understand is how best to split out the SII.

I expect that I'd just use Ha-OIII-Extract-OIII for the NB3 filter's OIII side. (correct?)

But for the SII... should I just pretend that it's Ha and use Extract-Ha for SII, or should use the (only)SII selection, or something else entirely? I don't really understand what's going on internally (bayer-wise) with these choices.

Thanks for your help with this!


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(@wvreeven)
Galaxy Admin
Joined: 4 years ago
Posts: 2035
 

@devonshire Hi!

Since both Ha and SII are Red, it will be impossible to split them. You'll need a filter that only has SII in the red part of the spectrum for this.

Wouter


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(@devonshire)
Main Sequence Star Customer
Joined: 5 years ago
Posts: 33
Topic starter  

Wouter,

Thanks for the response.  Separating Ha and SII wasn't the question - they would not be be mixed in the lights. The L-Extreme gives me red Ha data. The NB3 would give me red SII data, because it blocks Ha.

The question was how best to extract the SII red from the NB3's data.

Yes, the question down the road will be how best to assemble it all, but for now, I'm just trying to put a box around the SII extraction.


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(@wvreeven)
Galaxy Admin
Joined: 4 years ago
Posts: 2035
 

@devonshire Sorry, I misinterpreted the filter pass diagram and thought that both Ha  and SII were passed through. But you are right of course that it doesn't.

In that case you can use the extract Ha algorithm because the lights will be (undebayered) RGB files. The SII option is for mono lights.. Just keep in mind that APP will name the file incorrectly (which can easily be remedied outside of APP) but also the filter tag in the FITS header. Just make sure to select SII when you load the file in the Combine RGB Tool.


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(@devonshire)
Main Sequence Star Customer
Joined: 5 years ago
Posts: 33
Topic starter  

Ok - thanks!  Yes, that's fine.


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