Keeping with the starless nebula theme here is the Helix Nebula which is mostly Ha 500 minutes for a total of 10 hours LRGB plus Ha.
STL11 and RCOS 12.5 inch at F9 on a Tak NJP mount from my dark site a couple of months ago.
I used a tip from the Photoshop tips to remove the bulk of the stars and healing tooled out the rest.
The tip was to make a layer and blur it with gaussian blur to remove the stars. I used a layer/hide all to do this and
brush out the stars. Then use healing tool set very small so as not to affect the surrounding neb too much.
http://upload.pbase.com/image/100759044
Greg.