Heya Filip,
Have you taken some darks with the setup? This might also quickly help to narrow things down.
I asked someone the other day about the 533MC, whether they still used darks given the super low noise of the sensor. They said most certainly yes.
(Also, I used to live in SoHo, and sometimes wish that I still did! What a spot
)
JP
PS - nice colour choice on the focuser... rig is looking so nice!