The Helix is one of those objects where structures are distinctly different in OIII and Ha.
OIII(RGB) 10 hrs OIII 1 hr each RGB.
Ha(RGB) 6 hrs Ha 1 hr each RGB.
BRC-250 scope STXL-11002 CCD.
High resolution comparison here.
http://members.iinet.net.au/~sjastro...II_Ha_comp.jpg
Clear skies
Steven