After capturing 101x1800s combined in Ha and OIII for the Crescent nebula, I thought it may be of interest to show a comparison between the two lots of data.
I know that the outer halo is something of a difficult capture and it really does only show up in OIII........ The comparison is 50x1800s in Ha and 51x1800s in OIII. There really is some quite pronounced differences.
Sara Wager is an astrophotographer with published articles and images to her name