Quote:
Originally Posted by gregbradley
Yes I noticed the detail there - that is great. That's the power of the 20 inch aperture.
I saw yesterday Planewave are now making RCs .... The seeing though seems to be the limiting factor as usual. Greg.
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I agree with you about the seeing. Even the best seeing here (say 1.8 sec arc) is still far worse than the spot size in the extreme corners.
We find that the CDK with its spherical secondary is very easy to collimate. This is especially important for our set-up where the collimation screws are four metres above the ground. (Trish takes 20 second photos 1.5 mm out of focus, while I hang from the dome by my heels and adjust the secondary.)
A superb Ritchey-Chretien might outperform a superb CDK in the Atacama desert, but my vague understanding is that it requires skill to collimate, and an unskilled attempt might negate all the expensive benefit.