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Soul Nebula - combination of two duoband filters to produce SHO


StuartT

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2 minutes ago, simmo39 said:

V nice, was the combination of the data straight forward? 

I created the Ha, Oiii and Sii channels from the RGB of each filter (using the response curves of my camera), then merged the two Oiii channels (as both filters pass that). Then did an LRGB comb (black L and SHO for RGB). 

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5 minutes ago, Stuart1971 said:

I think you could go a bit more on the processing too, hope you don’t mind, but had a little tweak….not sure if it’s better or not…but the first looked a bit dark on my screen, but maybe it’s just my screen….🤔

 

7D531C09-3F79-4402-BDBB-8FD84F89ABA9.jpeg

I agree. In fact, I just posted a slightly more stretched version to Astrobin. (Original now replaced). Thanks

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1 minute ago, StuartT said:

I created the Ha, Oiii and Sii channels from the RGB of each filter (using the response curves of my camera), then merged the two Oiii channels (as both filters pass that). Then did an LRGB comb (black L and SHO for RGB). 

When merging the 2 Oiii channels did you combine them post stack or did you combine as a separate stack? Sorry for the interrogation.

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5 minutes ago, simmo39 said:

When merging the 2 Oiii channels did you combine them post stack or did you combine as a separate stack? Sorry for the interrogation.

Here is what I did.

Initially from the frequency response curve for my OSC I estimated the proportions of RGB that make up the three emission lines.
Hα = 80%R + 15%G + 5%B
Oiii = 95%G + 45%B
Sii = 75%R + 15%G + 5%B

Method
1 integrate data from each filter separately

2 SPCC each image

3 Register the two images

4 For L Extreme filter
split RGB
create Ha = 0.8*R + 0.15*G + 0.05*B
create Oiii_LExt = 0.95*G + 0.45*B

5 For Askar Oiii / Sii filter
Split RGB
create Oiii_A = 0.95*G + 0.45*B
create Sii = 0.75*R + 0.15*G + 0.05*B

6 Add the two Oiii images with simple addition
Oiii = Oiii_LExt+Oiii_A

7stretch the three images (Ha, Oiii, Sii)

8 Use LRGB combination
L blank
R Sii
G Ha
B Oiii

9 Postprocess - as usual

ZWO ASI2600MC Pro - frequency response with major emission lines.jpg

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2 minutes ago, StuartT said:

Here is what I did.

Initially from the frequency response curve for my OSC I estimated the proportions of RGB that make up the three emission lines.
Hα = 80%R + 15%G + 5%B
Oiii = 95%G + 45%B
Sii = 75%R + 15%G + 5%B

Method
1 integrate data from each filter separately

2 SPCC each image

3 Register the two images

4 For L Extreme filter
split RGB
create Ha = 0.8*R + 0.15*G + 0.05*B
create Oiii_LExt = 0.95*G + 0.45*B

5 For Askar Oiii / Sii filter
Split RGB
create Oiii_A = 0.95*G + 0.45*B
create Sii = 0.75*R + 0.15*G + 0.05*B

6 Add the two Oiii images with simple addition
Oiii = Oiii_LExt+Oiii_A

7stretch the three images (Ha, Oiii, Sii)

8 Use LRGB combination
L blank
R Sii
G Ha
B Oiii

9 Postprocess - as usual

ZWO ASI2600MC Pro - frequency response with major emission lines.jpg

Thank you that is a brilliant walk through, I may be getting the D2 filter my self v soon and this will help me a lot with my luddite understanding of these things. 

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5 minutes ago, simmo39 said:

Thank you that is a brilliant walk through, I may be getting the D2 filter my self v soon and this will help me a lot with my luddite understanding of these things. 

I found I needed double the exposure time for the D2 as Oiii and Sii are fainter than Ha. So I used 300s for the L Extreme and 600s for the D2

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