Quote:
|
Originally Posted by asimov
Thanks for that tid-bit Geoff..To put it in laymans terms...Your saying not all eyepieces are 'corrected' to work in fast telescopes, their really designed for slow instruments. It's only since they've been producing fast scopes...mainly for amateur astronomers...that they realized they had to produce some 'corrected' EPs to overcome the coma created in a fast scope.(hence the invention of naglers/pentax & the like) So therefore, a paracorr would only work with EPs that have been specifically designed (corrected) to work in a fast scope.
|
Im not 100% sure from what you said that you understood what I was trying to say, so I'll rephrase.
Coma is a function of focal length only. As you get further away from the optical axis taking in a wide field view in a fast scope, coma can become an issue. Away from the optical axis, a parabolic mirror cannot focus to a perfect point and coma is the result. A coma corrector reduces this effect.
As for eyepieces, simple and cheap designs cannot handle the steep light cone from a fast scope and produce a sharp image across the field, resulting in abberations. This is
not the same as coma.
So , a coma corrector wont make up for deficiencies in eyepieces.
I hope that helps.