Quote:
Originally Posted by mental4astro
28mm RKE, 25 to 30 year old design, no coma: $20
30mm TMB Paragon, 3 yr old design, coma: $300
+
Coma corrector: $ 250
mmm....
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Many (most) eyepieces do not handle the steep cone of light form a fast scope and show astigmatism at the edges (seagulls). A coma corrector will not help here. With a cheap widefield you won't even see the coma for the astigmatism!
As far as I know, no eyepiece will help with coma. Coma is related to the parabola-ised mirror - not the eyepiece - and will show itself as comet-like stars with the tails pointed away from the center of the FOV.
So a well-corrected eyepiece (like Naglers) will avoid astigmatism and a coma corrector will help with the coma.
