StarTools

I have never tried this so apologies for questions that obviously are off track.

I have a duo ban L-Extreme. It makes very nice, red images.
But (uh oh) I watched a you tube video that suggested that people use APP to "extract" Ha, OIII, and OIII mono.
Then, and NOT specifically in ST, use "Ha" as R, OIII mono for L, and OIII for B and G.
Will something along these lines work in ST? Or something slightly different? And which compose mode would I use?

I was told to, one at a time in Compose module, extract red, green and blue channels from your fts file. This takes a little time. Do not jump to next color too quick, wait until it is done loading. My computer has locked up if I don't wait. Then select " L +Synth L From R(2xG)B, R(GB)(GB)(Bi-color from OSC/DSLR).
Keep and then select Linear. Then process as normal. Once I get to the color module I choose HOO at bottom right. I use this with success when using my Optolong L Enhance.

That is correct; I also have the L-Enhance and do the same in Compose; works great. To quote the Great Ivo's steps from a couple of weeks ago:

With 1.7, there are now composite modes available specifically for duo/tri/quad-band filters.

Load dataset as Red, again as Green, again as Blue. StarTools will extract the channels automatically.
Set "Luminance, Color" to "L + Synth L From R(2xG)B, R(GB)(GB) (Bi-Color from OSC/DSLR)".

Luminance will be created by adding R, 2xG and B together, while coloring will be Red, Green+Blue and Green+Blue for Red, Green, Blue respectively. This the standard/popular HOO palette. You can remap it in the color module to something later.

Hope it helps.

Nick

Ok.

Well thank you for that! Certainly different from what I would have known to do. But those are steps I should be able to follow, and I will definitely give that a try.
Appreciate the suggestions I will write down these steps!