@Mike in Rancho is fast becoming another ST greybeard around here.
As I wondered as well, the ISO may have been a bit low, but then I looked up the specs of the 80D, and
it appears ISO 200 is indeed entirely reasonable.
(the way to interpret the Dynamic Range is to look for the first stop, from left to right, where the line becomes "straight" - this is the point where you get a linear relationship between signal collected and dynamic range used up).
You could try a higher ISO, say 400 next time, but I now doubt that would make any significant difference.
As I surmised, the biggest issue is
probably just the object being faint, while imaging from a Bortle 5 location with an unmodified camera.
As Mike also commented, definitely check your flat frames, as there is definitely uneven lighting going on, even showing faint hints of dust donuts; if you are going for faint objects, your flats need to be impeccable. Without being able to trust whether something is faint detail or dust donut (or vignetting, etc.) it becomes impossible to rescue faint signal from the murk.
CLS filters pass through much of the visual spectrum, however will cause a notable absence of yellow. E.g. a "correct" visual spectrum rendering is pretty much out of the question. However, you could consider using the bi-color preset to create a nice, distinct separation between the emissions in the red part of the spectrum (S-II, Ha) and the emisisons in the blue+green parts of the spectrum (O-III, Hb).
So, all up, super quick process, just for demonstration purposes;
AutoDev, Bin, Crop, Wipe (Vignetting preset, increased Gradient Aggressiveness), AutoDev (defaults), then Color module (Bi-Color preset), finished off with the Isolate preset in the Super Structure module;
-
- Crescent Nebula.jpg (574.46 KiB) Viewed 3141 times
E.g. please embellish, tweak to taste, chop and change. It's just to give you an idea. The cyan an Ha corresponds reasonably well with that from Ha and O-III renditions (or even SHO renditions) on, for example AstroBin. The one major issue is your flats, which makes faint nebulosity "iffy".
Hope this helps!
There also did seem to be some vignetting here, despite your flats, so I did use the vignetting preset in Wipe as a starting point.
Well, I did read here for many months before joining. Participating and trying out user data is more fun though, and better learning.