Re: [ATM] 40" mirror

[Jeff Anderson-Lee <jonah@eecs.berkeley.edu>]

What kind of scope do you want (Newt? Cass? R-C? Appl-Greg? ...)? For 
what purpose (visual? imaging? both?)?  What overall f-ratio are you 
shooting for?  Field of view?  Will you use a corrector of any sort 
(e.g. Paracorr or custom)? Are you planning a slumped, web-back, or 
solid mirror?  What kind of glass?

There are lot's of questions that might make a difference on the answer.

Jeff Anderson-Lee

Jerry B. Hillman wrote:

>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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