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Problem resolved tonight
Re collimated scope
Cleaned 2600MC sensor and protective window plus installed new desiccant tabs
Tried my DSLR in the scope , round stars with 60 sec unguided subs
Installed the 2600MC , still wonky stars
Hmm.... penny dropped, must be my spacing on the coma corrector as the scope is an f6 whereas my bigger scope down south is an f5
Reduced my spacers up and down by 0.5mm and took test subs for review
Ended up with no spacers at all ( so 55mm neat to sensor ) and stars round to almost edge of field , just a bit of coma on the left hand side edges and corners only, right side perfect to edge and corners
Why this has happened now , and not a year or two ago , I have no idea
The camera sensor could have been a bit dirty or some moisture around but I doubt it
Ran a 300 sec sub and checked Star shape, all good
So now my 6” f6 newt requires no spacers
My 8” f5 newt requires 4 x 0.5mm spacers
I just received and built my 10” f5 Carbon fibre Newt today but no EQ8-R mount yet , it 3 to 4 weeks away , so another round of testing for Star shape when I build the new rig down south
Thanks for all your advice and assistance
Much appreciated !!
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