Re: A Gregorian telescope

Advantages are erect image and only concave mirrors. Disadvantages are length (longer than 'equivalent' cass) and severe off-axis coma.

Is it true that the off-axis aberration is of an inverse nature? I read or heard that somewhere and was wondering if anyone could confirm or deny it. That is, if you had a wide field eyepiece with the typical edge distortion the positive curvature of the eyepiece and the negative curvature of the gregorian field could actually null each other out to some extent.