Let’s say I have a stack from 60×180s subs and a stack from 30x 60s subs. Does it make sense to stack the two master stacks together? Or will the 30x 60s stack degrade the image quality and am I just better off using the 60x 180s stack only?
Don’t combine stack like that.
You need to use HDR software
You may preprocess and process separately each exposure sequence, in Siril, and try to composite your images with layers in Gimp
I have 200x 10min subs with a duo narrowband L-Ultimate HaOIII 3nm and an Altair SIIOIII 6nm. My goal is to make an SHO image by splitting the rgb channels and recombine as SHO. I first stack the HaOIII and the SIIOIII separately. But there are 2xOIII channels and I want to stack them to improve SNR and lower the noise. So can I do that with a simple stack?
One way to do this is to process the two exposures separately, using the OSC preprocessing script.
Then make a new parent folder, name it the name of your target, add the word “combined” and create just a lights folder in that parent folder.
Then go back to your respective exposure folders and open the “process” folder. In there look for the “pp_lights”. Ignore the pp_lights seq file. Copy all those pp_lights files into the lights folder inside that new “combined” folder.
Do that for both your exposures.
If you haven’t already, download the OSC_Prepreocessing_WithoutDBF.ssf script. Then set your home folder in Siril to the “combined” folder and select the OSC_Preprocessing_WithoutDBF.ssf script and off you go.
In the “process” folder of your respective exposures you will also find “r_pp_lights”, ignore those they are the already registered lights files.
Good luck
Just some clarification: Instead of copying the pp_lights files, you can move them into the new “combined” folder, thereby saving disc space.
Also, I forgot to mention, you should re-name the pp_lights of the 30sec exposures by adding something like N2 (night 2) to all the file names, otherwise the computer will tell you that these files are already in the folder.
That’s not the answer I’m looking for. Can I just stack the green channel from HaOIII and SIIOIII together. Let’s say I used same exposure time/gain/offset and same total integration time for both filters. The only difference is one is 3nm and the other 6nm.