Hi Antoine, I try to see it as a challenge to do astrophotography from my windy hole by the Northsea :) And if I ever get better at this hobby (and this pandemic is over), I plan to combine it with holidays in the south of France or Spain to get better conditions. As for the dew heater, would a dew heater for a 8" help when wrapped around the tube where the knobs for the spider vanes are, I personally doubt it? Kind regards, g.

Hi Dalia&Antoine, thanks for having looked into it. I posted this on stargazerslounge as well, and there was none of the commentators that was sure of what was going wrong. As for the dry night, if I would have to wait for that, I might as well give up this hobby. Here (Belgium) after a few hours outside, it looks as if the whole setup has been showered. Furthermore since I took these images - 15 DEC 2020 - there has been not one clear night. So sorry, but don't expect any thing soon. Maybe I should consider radio-astronomy ... g.

Hi Dalia & Antoine, no problem; here's a jpg version (don't go hard on me, I'm just beginning, there were no flats, and the purpose of the session was mainly to see if these strange diffractions spikes were still there after some changes). Thanks a lot for your help! g.

Hello, thanks for your reply; you can find a stacked result (with APP) here: https://we.tl/t-jB7gpyQ8XS . I did not take any flats as the purpose was to see if the problem was still there after a couple of corrections (but that you will have guessed looking at the image 😉 ). There is some indication at the edges that the collimation is not perfect (as from previous post, I just cannot get this secondary mirror collimated), but the problem of the non-perpendicular diffraction spikes is also visible in the center of the image. An other weird thing is that the "horizontal" diffraction spikes show a light refraction, which makes me suspect there's an optical problem as well.(comma corrector???). Please don't go hard on me concerning the quality of the image, I'm just starting astrophotography and thank you very much for looking into this. Kind regards, g.

Antoine & Dalia, thank you very much for the swift answer; unfortunately - with the bad experience with my C8 - I leave the scope permanently outside under a car cover, so I'll have to wait for good weather to do my "practicing". g.