M20 and M21 with less data but more "sciency"

[Benjamin]

I reprocessed my M20 to include M21 (which meant discarding a bunch of rotated subs) with a view to keep the colour relationships between the Ha, [OIII] and [SII]. I still inverted the image, stripped the green (flip side of purple) and re-invreted the image to get something that resembled natural star colour. I usually strip the green after stretching the image but in this case opted to keep in to better represent the Ha. When tweaking colours I used starless Ha, [OIII] and [SII] masks rather than colour masks so that I would keep some kind of integrity to the SHO colour mix, while keep the stars mostly untouched. An odd image for me but felt the result was interesting enough.

Astrobin: https://www.astrobin.com/full/dr0bnt/0/

[multiweb]

I understand there is a trend of no green just blue and orange renditions that were started in the past by a few and subsequently fostered by most until it became some kind of standard but this is a lot more interesting and telling as far as NB goes. Colours mean something and are clear cut in all areas of the field. Not doctored to comply with an artificial and accepted look and feel. That's an awesome shot. :thumbsup:

[Benjamin]

Thanks Marc. I did also try a version where I did strip the green but kept colour manipulations based on the relevant emission masks. Ha ended up going Red, [OIII] stayed blue and [SII] headed toward yellow. I haven’t tried it but would seem to make more sense to map HSO for this colour scheme?

[Benjamin]

Quick correction. I realised I had stripped some purple from the image when I corrected the purple stars. I added an [OIII] starless nebula mask when stripping the green from the inverted image and this seems to have kept the purple hues in the nebula itself (just below the main core) which is a more accurate depiction of the [SII] and [OIII] in this area (blue + red = purple). It's only minor but trying to pursue an image that better locates the various emission lines.

Astrobin: https://www.astrobin.com/full/dr0bnt/B/

[Andy01]

As Spock would say - "Fascinating". :thumbsup:

[Benjamin]

And because I just had to see here is a HSO version following much the same principles as before...