OSC dual band subs

[sinbad40]

This may be a daft question, and i may have answered it myself, but, as i have OSC cameras, I am looking at getting dual band filters, Ha/OIII and SII/OIII (i wont be going to mono).  Is it just down to getting as much data as possible with an even split of subs, or is there a percentage for each filter, something like 60/40%.  I understand you can make adjustments when processing, but just wondered if its best to spend more time on one than the other.

 

[Lee_P]

This is a good question. For optimal results it's probably best to alter your times and ratios based on which specific target you're imaging -- but speaking personally, I like to keep things simple and just try to get a little more SII/OIII, given how weak the SII often is. That also helps boost the OIII. Here are some examples:

Cygnus Wall
– Optolong L-Ultimate (Ha / OIII): 540 x 120 seconds (18 hours)
– Askar Colour Magic D2 (SII / OIII) : 570 x 120 seconds (19 hours)
– No filter (RGB): 90 x 120 seconds (3 hours)

 

Butterfly Nebula
– Optolong L-Ultimate (Ha / OIII): 450 x 120 seconds (15 hours)
– Askar Colour Magic D2 (SII / OIII) : 600 x 120 seconds (20 hours)
– No filter (for RGB stars): 15 x 120 seconds (30 mins)

 

Soul Nebula
– Optolong L-Ultimate (Ha / OIII): 300 x 120 seconds (10 hours)
– Askar Colour Magic D2 (SII / OIII) : 420 x 120 seconds (14 hours)
– No filter (for RGB stars): 90 x 120 seconds (3 hours)

 

Edited October 10, 2023 by Lee_P

[ollypenrice]

24 minutes ago, Lee_P said:

This is a good question. For optimal results it's probably best to alter your times and ratios based on which specific target you're imaging -- but speaking personally, I like to keep things simple and just try to get a little more SII/OIII, given how weak the SII often is. That also helps boost the OIII. Here are some examples:

Cygnus Wall
– Optolong L-Ultimate (Ha / OIII): 540 x 120 seconds (18 hours)
– Askar Colour Magic D2 (SII / OIII) : 570 x 120 seconds (19 hours)
– No filter (RGB): 90 x 120 seconds (3 hours)

 

Butterfly Nebula
– Optolong L-Ultimate (Ha / OIII): 450 x 120 seconds (15 hours)
– Askar Colour Magic D2 (SII / OIII) : 600 x 120 seconds (20 hours)
– No filter (for RGB stars): 15 x 120 seconds (30 mins)

 

Soul Nebula
– Optolong L-Ultimate (Ha / OIII): 300 x 120 seconds (10 hours)
– Askar Colour Magic D2 (SII / OIII) : 420 x 120 seconds (14 hours)
– No filter (for RGB stars): 90 x 120 seconds (3 hours)

 

I don't know about the time balance (though it looks fine to me) but your total integration times are the real thing, and so are the images. All the images have a real 'three colour dimensions' feel to them, the Soul nebula above all. That's a wonderfully broad gamut.

Olly

[Lee_P]

32 minutes ago, ollypenrice said:

I don't know about the time balance (though it looks fine to me) but your total integration times are the real thing, and so are the images. All the images have a real 'three colour dimensions' feel to them, the Soul nebula above all. That's a wonderfully broad gamut.

Olly

Ha, the annoying thing is that the Soul Nebula pic was one of my very first experiments with the SII/OIII filters, and for the life of me I can't recreate the processing steps to get those exact colours! Maybe I'll have to dedicate a day to trying sometime. It's like modern-day alchemy...

Edited October 10, 2023 by Lee_P

[sinbad40]

Cheers Lee, That is what i am after, and it makes sense to get more of the weaker signal.

[bomberbaz]

21 hours ago, Lee_P said:

Ha, the annoying thing is that the Soul Nebula pic was one of my very first experiments with the SII/OIII filters, and for the life of me I can't recreate the processing steps to get those exact colours! Maybe I'll have to dedicate a day to trying sometime. It's like modern-day alchemy...

Can you explain how you got that colouration to the images please, were they stacked as mono but mapped to the hubble pallette or something along those lines or is that the actual colour you got during data capture. Totally stunning btw!

[barkingsteve]

Cuiv recently did a video using the 2 dual band filters, perhaps you may find some of the info useful

 

 

[Lee_P]

18 hours ago, bomberbaz said:

Can you explain how you got that colouration to the images please, were they stacked as mono but mapped to the hubble pallette or something along those lines or is that the actual colour you got during data capture. Totally stunning btw!

There's a bit of info here. I use a similar technique to the video posted above, but my own recipe! I'll make a processing video sometime. But it's basically about splitting the Ha/OIII and SII/OIII data into their constituent RGB channels, then giving them a stir and making S H O images which you then apply false colour to. It's a dark art!

Edited October 12, 2023 by Lee_P

[bomberbaz]

8 hours ago, Lee_P said:

There's a bit of info here. I use a similar technique to the video posted above, but my own recipe! I'll make a processing video sometime. But it's basically about splitting the Ha/OIII and SII/OIII data into their constituent RGB channels, then giving them a stir and making S H O images which you then apply false colour too. It's a dark art!

Yes had a little look this afternoon and also a bit of a play. Problem for me is I only use Siril and Gimp. Gimp automatically splits a fit file down upon loading but it doesn't do a very good job of converting back to colour. I read this is known of Gimp.

I do have access to astap too and AIP4win which both have some functionality in that area but as I am not very familiar with either it's a bit of a curve. 

[Ouroboros]

Just out of interest, @Lee_P, what gain do you use with your 2600 camera and dual band filters?  

[Lee_P]

1 hour ago, Ouroboros said:

Just out of interest, @Lee_P, what gain do you use with your 2600 camera and dual band filters?  

Always gain 100 and 120-second subframes, regardless of filter or target. 

[Ouroboros]

7 hours ago, Lee_P said:

Always gain 100 and 120-second subframes, regardless of filter or target. 

Interesting you use 120s. I thought I’d read that longer times are often used when using filters.  Have you tried longer subframes?

Edited October 13, 2023 by Ouroboros

[Lee_P]

2 hours ago, Ouroboros said:

Interesting you use 120s. I thought I’d read that longer times are often used when using filters.  Have you tried longer subframes?

Yes, but it didn't make any difference. The only thing I found that mattered was the total integration time. I settled on 120s a sweet-spot for me of not stressing my mount too much; and not producing so many files that my PC would melt during processing. Very almost everything here is made from 120s subs. Come to think of it, I've now got a better mount, and I'm producing longer integration times than ever, so maybe I should revisit this and consider longer individual subframes just to lessen the pressure on my PC harddrive and processor!

Edited October 13, 2023 by Lee_P

[Ouroboros]

My thinking has been very similar and so far I’ve only stuck with broadband OSC.    120s seemed a reasonable compromise for all the reasons you cite. It already takes overnight for my aged MacBook to process the subs. The poor old thing’s fan is whining away for hours on end. I’ve taken to raising it off the table slightly to allow air to circulate.  on the other hand lengthening subs runs the greater risk of having to throw away longs subs ruined by wind shake, planes, satellites, intermittent clouds etc.  Though I guess filters should reduce the contribution of satellite trails/planes. 

[Lee_P]

2 hours ago, Ouroboros said:

My thinking has been very similar and so far I’ve only stuck with broadband OSC.    120s seemed a reasonable compromise for all the reasons you cite. It already takes overnight for my aged MacBook to process the subs. The poor old thing’s fan is whining away for hours on end. I’ve taken to raising it off the table slightly to allow air to circulate.  on the other hand lengthening subs runs the greater risk of having to throw away longs subs ruined by wind shake, planes, satellites, intermittent clouds etc.  Though I guess filters should reduce the contribution of satellite trails/planes. 

I'm not bothered by satellites or planes. They get removed very effectively during integration. Wind and clouds on the other hand..! 

Edited October 13, 2023 by Lee_P