Re: [ATM] Klaas Honders Astrograph

[Jeff Lowe <lowe@nanotechsys.com>]

atm-request@atmlist.net wrote:
Message: 6
Date: Mon, 20 Aug 2007 21:10:28 -0700
From: "Bob May" <rmay@nethere.com>
Subject: Re: [ATM] Klaas Honders Astrograph
 >Which tolerances do you think will be better served with fused
 >silica?  BK7 should be quite well enough as one of the specs is
 >probably that the telescope needs to be all made of glass from
 >the same melt..  This insures that the indices are all the same
 >for the different lenses.

If you read Jim's new book you will see that the "Same Melt" criteria is 
a thing of the past (and may not have been really necessary then) The 
Schupmann in the McGregor Observatory at Stellafane does not have the 
same melt glass.

-- 
Jeff Lowe

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