I have worked on my polar alignment (CPC1100 on fixed pier) and getting much better tracking now (PhD with Orion Short Tube and Starshoot autoguider) so had 16 x 3 min images to stack in DSS (best of 20) iso 800 (Canon 500D with f6.3 focal reducer). 10 darks and some quick stretching in Photoshop but much happier with the clarity and tracking compared with my previous attempts. Have a lot to learn on processing yet so any tips very welcome.
Thanks guys. I was not sure how to lighten it up without what I think is some vignetting starting to appear, perhaps need some lights? Tried a Swan nebula tonight although not as precise with the tracking, perhaps a bit too low still and done earlier than last night with M20.
I took your advice and fianlly did some flats (cloudy day today and a white sheet over the scope and Maxim DL to set the correct exposure). I have resposted the original Trifid on the left and the new one with flats on the right and it has made it clearer and removed the vignetting around the nebula. Thank you for pushing me to finally get some done.
That's a very nice image. 
