It's getting better ...
After receiving the laser collimator, a better collimation was quickly achieved. Having now preliminary pointing capabilities, I start to take first easy pictures. For sure thousend times imaged - now - one more time Orion Nebular M42: in order to avoid over exposure, I started to image in H-Alpha. Flatfield not yet applied - and even not sure, if I can do it afterwords, because I think background is not true background sky - it's more driven by scattered light penetrades into the truss tube. In case, this is true, it would be hard to reproduce the conditions at the time the image was taken.
Next step will be to see if masking the tube has a significant influence on the brightness of the background.
M42 December 09th, 2015
STL11000M @ 510/2150mm Newton without corrector
H-Alpha @ 10x10s, binning=2 (pixelsize 18mue), no flat
Orientation: North->right, East->up.
(klick on image for FullHD resolution (if available) - shown in a separate tab)