Hi Ingo,
this is exactly what I have been doing, light polluted skies, Nikon D80, 50mm f1.8 and 70-200 f4?-5.6.
I am really impressed that you did Pinwheel nebula. What else have you taken photos off and with what settings?
I did Moon, Orion nebula and LMC - LMC is huge, I cannot see it by eye but camera with 50mm at high iso and 5 sec will make it visible straight away so you can align it in the centre of your view to take many photos for stacking.
Regarding taking proper photos, see this thread:
http://www.iceinspace.com.au/forum/s...ad.php?t=19189
Basically you need guiding and long exposures and lots of money to get you started, I was told that real imaging starts at $2k
I am not an expert in guiding as I don't even have a real telescope (yet) but from what I read you need an equatorial mount for the scope, a guiding webcam or some other guider which you point to another star and you slowly rotate the telescope to keep the star centered while taking a long exposure. Alternatively a motorised system will do the job.