After having lots of issues with dust donuts, I took the camera and filter wheel inside and cleaned them properly. The result, no more donuts!! This was a fairly short test as there was a 95% waning Moon. This did cast a gradient on the image but application of a DBE in PixInsight did a good job of removing it.

This was an RGB only run, of 10 x 3minute exposures for each filter. The telescope was the Takahashi FSQ106. Camera QHY268 mono. With 50mm round filters and an OAG for guiding. Capture was done by Sequence Generator Pro. Guiding by Phd (Freeware so go get it!).

Calibration, stacking and processing all done in Pixinsight.