askar c1 and c2 filters

General discussion about StarTools.
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alacant
Posts: 219
Joined: Mon Jan 25, 2016 7:03 am

askar c1 and c2 filters

Post by alacant »

Hi everyone
OSC with filters
c1: Ha OIII
c2: SII OIII

I made two stacks and extracted the Ha and SII respectively from each using Siril.
The OIII I made by combining the B and G channels from both stacks.
The registered and aligned files are here: https://drive.google.com/drive/folders/ ... drive_link

I then used Compose, SHO. The result is awful!
p1.jpg
p1.jpg (406.05 KiB) Viewed 1339 times
Question: do we have a StarTools recipe for combining these duo filters?

Cheers, CS and TIA,
Steve
hixx
Posts: 253
Joined: Mon Sep 02, 2019 3:36 pm

Re: askar c1 and c2 filters

Post by hixx »

I assume You used a color cam and split the channels. From one stack You'll get: R= Ha and G/B = O3. From second stack You'll get: R= S2 and G/B = O3
A better way might be to do a third stack with images from both filters to increase integration time for O3= G &B channels to reduce noise
Then load S2 into R, Ha into G and O3 into B channel and have a play with the presets There are loads of them.....
Clear skies,
Jochen
Mike in Rancho
Posts: 1160
Joined: Sun Jun 20, 2021 10:05 pm
Location: Alta Loma, CA

Re: askar c1 and c2 filters

Post by Mike in Rancho »

Hey Steve,

Short of time to check out the files, maybe on the weekend. Or a weekend after that lol...

But, you might consider ditching the B channel and only using G when creating the OIII file. Review the response graphs of your camera and the filters first, but for most OSC and duobands I think it should work fine. B can often be a weak and noisy edge, but the exact same structure usually falls through the filter bandpass and lands in the G. Frequently stronger, and of course you also have 2xG pixels. So, that OIII might end up cleaner when not averaging in the original captured B, especially if you are not using ST to bump the G's weight prior to extraction and combination. But sometimes even so.

Then of course your final OIII would typically be loaded into the B for your SHO in compose.

And when processing just play around with matrices as you see fit, along with the saturations, style, and LRGB emulation, as all can have strong effect on the resultant presentation.

Crescent could still "look" weird in SHO, as it is an object that we are maybe more used to seeing in bicolor. Or even RGB with Ha and OIII enhancements.
alacant
Posts: 219
Joined: Mon Jan 25, 2016 7:03 am

Re: askar c1 and c2 filters

Post by alacant »

Thanks everyone. I really appreciate the time taken for your replies.
You've confirmed my suspicion that leaving B out of the stack may produce a cleaner result.
It gives me new hope that there is no correct or agreed way to do this stuff and that experimentation is what it's all about. Perfect.
Cheers and CS
Steve
alacant
Posts: 219
Joined: Mon Jan 25, 2016 7:03 am

Re: askar c1 and c2 filters

Post by alacant »

hixx wrote: Wed Jun 19, 2024 7:51 am I assume You used a color cam and split the channels. From one stack You'll get: R= Ha and G/B = O3. From second stack You'll get: R= S2 and G/B = O3
A better way might be to do a third stack with images from both filters to increase integration time for O3= G &B channels to reduce noise
Then load S2 into R, Ha into G and O3 into B channel and have a play with the presets There are loads of them.....
Clear skies,
Jochen
Thanks, yes. That's exactly what I did. Still thinking...
Cheers
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