[ATM] 40" mirror

["Jerry B. Hillman" <JBHillman@ev1.net>]

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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