This shot is a kind of milestone for me because I had never taken an object with an integration time so long (about 11 hours). Furthermore it is also my first shot using the OIII filter (twice ionized oxygen) and this has led to some problems of mixing RGB channels in the band OIII. Eventually, also talking to Fabiomassimo, I convinced myself to insert the OIII band 100% in the blue channel.
As you can see the nebula is intrinsically very weak and the contribution of OIII, visible in the left ring of the nebula, is very small. The processing was further complicated by the fact that this object is located almost on the galactic equator, a region very rich in stars that complicate the highlight of the details of the nebula from the background.
http://www.skymonsters.net/immagine.php?img=CTB1.jpg
Comments and Criticism always welcome
Nicola