This is a narrow band S2, Ha, O3 image taken over 6 hours (2hrs each) in one night.
Imaged with my Altair Astro 70mm ED-Triplet and my ASI1600mm pro camera.
This image is a reprocess of the same data with slightly less green removal and a different crop.
Finally worked out that Automatic Background Extraction was causing my vignetting in processed images and not poor flats or something else in the data. I’ve had another go and produced an almost full-frame image (minus the few pixels for dithering) with better colour control and handling of the stars: