[ATM] Dall-Kirkham Coma Reduction?

[jcs5159 at yahoo.com (John Spero)]

I have a polished but unfigured 10" f/4 mirror laying around, and I thought I use it as a starting point for a planned Dall-Kirkham cassegrain project.  I've been looking at Takahashi's Mewlon series of D-K's for ideas for my scope, and several of the reviews of these telescopes claim that Takahashi masks the primary to reduce the coma inherent in the D-K design.  Although the Mewlon's do use an oversized primary (the Mewlon 250 uses a 260mm primary stopped down to 250mm), I don't understand how stopping down a D-K primary can reduce coma. Am I missing something?
 
John S.   


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