Re: ATM 16" F/33 valid design?

["Peter John Smith" <pjifl@bigpond.com.au>]

Somewhere in the Archives is set of of data I calculated about an extremely
high F:NO Cass made by using a standard lens as the secondary. It is hazy
now, but there was performance data on a series of F:NOs.  It is vaguely
interesting and would not be hard to try.

This may have been a month or two (here in Aust I get S&T quite late) after
it appeared in S&T.

There was quite a discussion on the merits (or not) of the idea, also
tolerances of commercial lens surfaces etc etc.  I personally consider this
could be a real trap.  Commercial refractive lens surfaces would be unlikely
to be better than about 1/2 wave so used in reflection this a real problem
if you are after top performance.  To make matters worse, the secondary is
working on the edge of the tolerance band because the ideal shape is not
spherical - although, as pointed out by others, the incredibly high F:NO
changes matters dramatically - things happen which we would not expect.

I just spent some time trying to locate it in the Archives without any
success.  It is probably buried under some stupid unrelated name.

>From memory, the writer of the article was trying to patent some aspect of
it !!!!!!!!!

Maybe some one else can find it.  If you know the date of the article this
will help.

Peter Smith.

PS.  I just thought of his name.  Something like Endemann from memory.
Anyway, searching costs me money so I will leave it to some one else.

Peter Smith.