RE: [ATM] 40" mirror

["Richard Klappal" <klappal@xnet.com>]

If I may suggest, before you depart on this voyage of discovery, stand on
the shoulders of giants and become familiar with the terrain by reading some
published information.  Some starting points might be ...

 * Rutten and van Venrooij, "Telescope Optics: Evaluation and Design", (c)
1988 Willmann-Bell, Inc. ISBN 0-943396-18-2

 * Mackintosh, "Advanced Telescope Making Techniques, Vol 1, Optics", (c)
2977, 1986, Willmann-Bell, Inc. ISBN 0-943396-11-5.  (Vol 2 of this set
covers  mechanical aspects.)

 * Ingalls, "Amateur Telescope Making", (c) 1996 rearranged and reprinted
3-volume set of books.  published by Willmann-Bell., ISBNs 0-944396-48-4,
0-944396-49-2, and 0-944396-50-6.

If you are not familiar with the chemistry and physics of glass
manufacturing and you are not familiar with the design of optical systems,
you have a LONG trail in front of you and there are no roadsigns on the
trail.  You have to have the maps before you leave.

-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net]On Behalf
Of Jerry B. Hillman
Sent: Wednesday, 22 December, 2004 17:46
To: The Amateur Telescope Makers List
Subject: [ATM] 40" mirror


Hello everyone,

Since I am going to invest a good deal of money and a considerable amount of
time in the venture of melting the glass and casting a 40" mirror, I would
like to hear anyones input about very large mirrors.
I am interested in hearing about F ratios compared to useability and
difficulty in manufacture.  I don't want to invest a lot of time making an
F2 only to find out that uncorrectable coma is the inevitable result.
Don't misunderstand me.  I have no idea if an F2 would have uncorrectable
coma.  I just pulled an example out of my hat to help explain what I need.
The first piece of glass I am going to cast is for the secondary.  I need to
know what the F ratio of the telescope is going to be before I take that
step so that the glass will be large enough.  I know that starting with the
secondary is sort of putting the cart before the horse, but casting and
annealing the secondary will tell me if my methods are feasible for a larger
mirror.
Clear skies, Jerry

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