From: "Mel Bartels" 
To: 
Reply-To: "Mel Bartels" 


What I have to say on large thin glass is at

http://www.efn.org/~mbartels/tm/largthin.html

Basically 16 x 3/4 inch plate glass is pushing the envelope.  It can be
done but the glass is very flexible and makes figuring challenging.  Also
you definitely want to keep the focal length as long as possible.  F/6 is
reasonable here.

My main comment is more to what you want from this project.  If you view
this as a hobby and you are happy to mess around with the glass and are
content that it might not work well and you don't want to pay the $$$ for a
thicker pyrex blank, then by all means, go for it.  If instead you are
looking for the easiest quickest 16 inch size to figure, then you should go
a different route.  Certainly it can be done, but it's no guarantee, and
it's not for everyone.  That being said, I have always viewed mirror
grinding as a hobby and thus am content to play around with the glass until
I get it the way I want.

Mel Bartels

--- BBBS/NT v4.00 MP