About the Rocolax UVIR blocking filter, last night I again take few shots of M33 without it. And I can confirm Bojan's measurement, this filter is not good for astrophotography. Without filter Ha regions are clearly visible.
On the other side, I am totally surprised with the stuff I can pull out from my cam84 v3.1 camera. Cam86 should be even better, with lower noise.
M33 from the last night:
(8x900s, gain 63, offset 12, CCD temperature -10C)
https://dl.dropboxusercontent.com/u/...uced_stars.jpg