Re: [ATM] Schmidt Cassegrain

["Richard F.L.R. Snashall" <rflrs@rcn.com>]

Michael Peck wrote:

>
> If you want to try an interesting guessing game how about reverse 
> engineering Meade's new line of Ritchey-Chretien telescopes 
> <http://www.meade.com/rcx400/>? They claim to correct astigmatism with 
> a front corrector element, but from the information available it's not 
> clear if it's a Schmidt like thin plate or a meniscus. I'm guessing 
> it's a thin plate. 

That's this week's guessing game.  But, as you say, with two oblate
ellipsoids, it can hardly be considered a Ritchey-Chretien; but it
does remove some of the astigmatism.

The spot diagrams given in that ad are a bit out of scale (typical
Madison Avenue comparison of blech against a design) for me to
guess the size.  But it is smaller than the 40 micron size in this
design, but that could be simply the choice of a single "best"
wavelength (587.5 nm -- d line).

>
>
> Mike Peck
>
>


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