Hi Paul,
Nice shot of the Helix. A couple of questions though.
Firstly, Are you sure that the red on the right is nebulosity, or is it gradient? I ask because I have seen images of the helix with a red loop on the opposite side, but nothing like what you have on the right.
Secondly, the green in the centre is interesting. Did your subframes show this colour, or is it processing?
Again, great shot. Well Done