Re: [ATM] 6 inch F-8 to F-10

["Richard F.L.R. Snashall" <rflrs@rcn.com>]

Richard F.L.R. Snashall wrote:
> Actually, it is the other way around -- the design would be
> modified to fit what is cheaply available.  I just happened
> to find one that fit neatly against those values -- knowing
> that, at one time, 6" f/8 to f/10 was the "norm" (before
> ATMing took up rocketry), I thought there might be a chance
> of a surplus source for some of these.
For example, if the mirrors are f/8:

    http://users.rcn.com/rflrs/schiefsp01-26y.atm   ATMOS input file
    http://users.rcn.com/rflrs/schiefsp01-26y.len   OSLO input file
    http://users.rcn.com/rflrs/schiefsp01-26y.txt   TEXT prescription
    http://users.rcn.com/rflrs/schiefsp01-26y.zmx   ZEMAX input file

The final system here ends up at about f/11.7.  Over the nearly
two degree field, the Visual Strehl is above 0.87 (about 0.947
in the field center).  Yes, it could use some figuring (SC = -3.24
on the f/14 primary), but all-spherical still looks respectable.
But, again, it has four mirrors -- perhaps a bit of an expense
for a 106 mm f/11.7, unless some it comes inexpensively.

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