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Originally Posted by Itchy
Hi Paul
Nice test shots for the MPCC. I can't detect any coma at all. My MPCC arrived over a week ago and I can't get a clear night to try it out. Some people think that it will overcorrect on the SN scopes as there is already a corrector plate (although still considerable coma). I'll find out one of these nights!!!
Cheers
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Geeday mate,
yeah the MPCC is great. I know what you mean about the weather, I had to sneak out around midnight a few nights back when the skies partially cleared for a little while. But really the conditions were poor, the seeing terrible, but just enough clear sky to try out the coma corrector on M42.
As far as overcorrection is concerned: I would say you have nothing to worry about. The fact that your 'scope has a corrector plate is not an issue, your 'scope has coma and the MPCC corrects that - it wouldn't matter if your 'scope had a triplet-overhead-single-bypass lens or whatever - you 'scope produces coma at the film plane and the MPCC corrects the coma.
In fact another IIS member (tornado33) is using he's MPCC with a f/3.6 Schmidt-Newtonian and he's over the moon, since it always produced a fair bit of coma and now it's all but gone!
Baader say that the MPCC is designed for f/4 to f/6 telescopes and works best when the MPCC is placed 55mm from ccd plane. It turns out mine is 54mm, so I might fittle to add 1 mm.
What f/ratio is your 'scope ?
Paul M