Quote:
Originally Posted by Atmos
From what John was saying it sounds like the focus thing shouldn't effect your CDK as it isn't what would be considered a classical SCT. From memory the DK design works with two hyperbolic mirrors as opposed to having a parabolic primary on the SCT. The CDK also has a corrector (possibly in front of the secondary??).
As for how this translates to visual performance outside of the large secondary... I have no idea  |
Hi Colin,
the CDK has a parabolic primary and a spherical secondary. the corrector lives just in front of the focuser so basically smack in the middle of the primary mirror itself.
those were my thoughts too, given that the primary and secondary are not being shifted to achieve focus, i am not sure how the optical performance will be impacted. for sure the secondary is going to be a problem, particularly for high contrast ... but is it going to have the same issue as a SCT. John probably knows a heck of a lot more about this than i do so keen to get his thoughts, i might have missed the mark in terms of understanding the issue.