From: Steve Beccue 
To: atm{at}shore.net
Reply-To: Steve Beccue 



I wish to make a 12" schmidt camera.  I have some 1/4" thick
12.25" diameter plate glass for the corrector.  I searched the
archives and found people suggest Nd=1.523.  Does everyone agree this is a
good value?

I was hoping to make a F/2.5.  Any comments on the utility of this focal
ratio?  I only choose it because I'll have a 1/4 scale model of the palomar
schmidt.

The raytrace I have done gives rediculously good spots 50mm off-axis.  Is
this reasonable?  Is this design tolerant enough that real world tolerances
give anything near this nice?   Does this, in fact, justify a
4" x 5" film holder?

TIA

Steve Beccue
steve{at}beccue.com

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