Playing with duoband colors - and sooo many stars!

Questions and answers about processing in StarTools and how to accomplish certain tasks.
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dx_ron
Posts: 268
Joined: Fri Apr 16, 2021 3:55 pm

Playing with duoband colors - and sooo many stars!

Post by dx_ron »

As the Milky Way starts coming into view again, I've started imaging the Tulip Nebula with the AT130EDT + L-Ultimate 3nm duoband filter. Not finished yet, but with 9.5 hours and clouds, moon and an upcoming trip I started playing around with processing.

There's a lot to play with at Optidev time, between highlighting the tulip shape vs stretching the other Ha parts and trying (or not) to maximize visibility of the mostly Oiii bow-shock from the Cygnus-X1 black hole in addition to the pink v red Ha axis.

Here is the basic default color settings after a stretch focused on the tulip shape:
Tulip_Lu_115x300s_bicolor-default-pink.jpg
Tulip_Lu_115x300s_bicolor-default-pink.jpg (497.58 KiB) Viewed 2233 times
It turns out that quite a lot of the "problem pink" can be dealt with simply by maximizing Dark Saturation:
Tulip_Lu_115x300s_bicolor.jpg
Tulip_Lu_115x300s_bicolor.jpg (484.3 KiB) Viewed 2233 times
Last edited by dx_ron on Wed Jul 10, 2024 12:51 am, edited 1 time in total.
dx_ron
Posts: 268
Joined: Fri Apr 16, 2021 3:55 pm

Re: Playing with duoband colors

Post by dx_ron »

I also tried separate mono processing of the Ha / Oiii (separating the channels in Compose), followed by RGB/RGB Legacy recomposition:
Tulip_Lu_115x300s_Ha-Oiii_test_v1.jpg
Tulip_Lu_115x300s_Ha-Oiii_test_v1.jpg (499.71 KiB) Viewed 2232 times
and
Tulip_Lu_115x300s_Ha-Oiii_test_v2.jpg
Tulip_Lu_115x300s_Ha-Oiii_test_v2.jpg (489.52 KiB) Viewed 2232 times
I like the colors best that way, though some brightness tweaking will be needed. One problem is that making any change in how the colors get balanced requires reprocessing one (or both) channels from scratch.

I do not plan to try to coax sky blue into the center of the main nebula, as many do on astrobin. Yes, that is where the Oiii signal is strongest - but it is also where the Ha signal is strongest.

[lots of work to do on stars, and I did not bother to try to be consistent across these images]
Mike in Rancho
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Joined: Sun Jun 20, 2021 10:05 pm
Location: Alta Loma, CA

Re: Playing with duoband colors

Post by Mike in Rancho »

Pretty cool! As I was going down the set and things became darker and more red saturated, I was thinking myself that getting white back into the core would probably look the best. And the last image got there!

Heavy star field though, gosh. So maybe that could be pushed back just a bit in the final, whilst retaining the target as-is. Perhaps some usage of SS, or adjustment of black point more or less?
dx_ron
Posts: 268
Joined: Fri Apr 16, 2021 3:55 pm

Re: Playing with duoband colors

Post by dx_ron »

Crazy how many stars there are in the Milky Way, ain't it? :lol: Yeah, something will need to be done. I collected about 1.5hr of OSC stars for it, also. Hope to gather a bunch more duoband time next moon cycle, when it will be high enough at full dark to not have to find any filler target.
dx_ron
Posts: 268
Joined: Fri Apr 16, 2021 3:55 pm

Re: Playing with duoband colors - and sooo many stars!

Post by dx_ron »

17 hours of duoband now, and 2 hours of OSC stars.

HOO, with R and G/B processed separately as mono, then combined using RGB/RGB Legacy:
Tulip_HOO_Ha_v3_12_shrink-dim_SS-50_NR+Oiii_v3_HDR_shrink_iso_NR+OSC_v3.jpg
Tulip_HOO_Ha_v3_12_shrink-dim_SS-50_NR+Oiii_v3_HDR_shrink_iso_NR+OSC_v3.jpg (661.6 KiB) Viewed 1733 times

and "HxO" (nothing loaded into the green channel):
Tulip_HxO_Ha_v3_12_shrink-dim_SS-50_NR+Oiii_v3_HDR_shrink_iso_NR+OSC_v3.jpg
Tulip_HxO_Ha_v3_12_shrink-dim_SS-50_NR+Oiii_v3_HDR_shrink_iso_NR+OSC_v3.jpg (679.08 KiB) Viewed 1733 times
The stars look kind of OK when the image is viewed as a thumbnail, but go to full size and there's an endless number of equally dim stars (the work of SS and Shrink) pretty much obliterating the fainter parts of the nebula.

Should I resort to <gasp!> starnet?

It's all an interesting exercise, what with having to make a new file with reprocessed Ha and/or Oiii mono for any tweak to the balance and stretch.
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