Quote:
Originally Posted by toryglen-boy
So, i get bad coma on the F5 scope when taking pictures, and i use an MPCC, although i found it tricky to get the spacing right, so i ordered the QHY8 MPCC back focus matched adaptor from Peter Tan, and although its machined very nicely and fits, but i still get coma, even though i am using the right spacing (55mm)
Also, i get really bad reflections of the colimation marker in the primary when i use the MPCC, and i mean REALLY bad, any brightish stars in the image, produce a red doughnut, right next to it.
Have any of our QHY8 and MPCC users managed to do anything about getting the right spacing, and getting rid of reflections?
thanks
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Hey Duncan, I have the exact same configuration as you. F/5, MPCC,QHY8. Here's what I do.
1_ I use a custom telescopic adapter that Peter Tan made for me. He's go the blue prints. 55mm was too short of a distance in my case.
2_ I got a NULL adapter (no glass) to replace the standard nosepiece. No more reflections from the MPCC glass onto the nosepiece glass.
3_ I flocked my scope. No stray light and reflections.
4_ I tried to collimate it real real real good. Well as good as I could but you get the idea.
All in one it made a huge difference. I'll still get halos if I push exp time on alnitak or M45 but that's a given with pretty much any scope. HTH.
