[ATM] Meade 'Fesses up

[Michael Peck <mpeck1@ix.netcom.com>]

Sorry to bring up everyone's favorite commercial telescope maker yet again, 
but some of us were puzzling over the optical design of Meade's new line of 
"Ritchey-Chretien" telescopes. It seems Meade has quietly added some 
verbiage to their web page announcing the product in the past few days and 
has solved the problem for us. Here's the key new line:

>The RCX design is very similar to the Classical RC and achieves the same 
>benefits by using a hyperbolic secondary with a new advanced front 
>corrector plate and primary mirror that together perform as a hyperbolic 
>primary.

To anyone who knows a little about optical design and can read between the 
lines a bit what they're saying is they're using their usual spherical 
primaries with an aspheric secondary to produce an aplanatic SCT. For a 
primary f/ratio of 2 and secondary magnification of 4 they would need a 
hyperboloidal secondary, and the design will have significantly lower 
astigmatism than a true RC. Of course they don't mention field curvature or 
spherochromatism, both of which are going to be fairly substantial.

Here's my other favorite line from the addendum:

>While the RCX optical system is significantly more expensive to 
>manufacture than a Classical RC, it was chosen because of its superior 
>performance (i.e., no diffractions spikes, reduced astigmatism and closed 
>tube).

(snicker).

I hope this doesn't generate too much "Meade sux" type commentary. We don't 
want management to have to intervene.

Mike Peck

------
Michael Peck
mpeck1@ix.netcom.com

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