Re: ATM Generating curves (Mak issues)

[Anthony Stillman <atmer@flash.net>]

>mak-newt (verses) newtonian performance...
>on the planets

>closed tube...spiderless obstruction...
>what else...?

>...maks...less ..availible
>in apertures much greater than 200mm
>D Chaffee

Dan,

Curiously, Mark V., I and others had this discussion last Friday at the
Chabot Mirror making workshop.  Bill M. was on the side lines and there was
general consensus that his Mak will be truly a fabulious instrument when
complete.  Bill showed me the finished corrector, its very pretty, and
quite heavy.  This I think is a is a serious limiting factor.  Since, in
general, lengths ratio up, that is, we opt for the same f/, the weight of
corrector goes up with the cube. Hence, the corrector for a 300mm will
weigh in at 8 times that of a 150mm.  Also as you note, the cost of a blank
of sufficient thickness and quality from which these steep curves can be
generated quickly becomes prohibitive.

My interest in Maks lies not just in the beauty of the design, but also in
its impressive performance over a wide field.  It is highly non-chromatic,
compact,  and of course fabracation of steep spheres is much easier that
any asphere I've attempted.

Like Bratislav, I've also considered an off-axis Mak.  The prismatic
corrector is likely only slightly more dificult than an ordinary corrector
(this I infer based on a few discussions with a master optician and
professional optics program manager)  In fact this design variation opens
up a whole collection of possibilities, a higher magnifacation ratio, a
Gregorian Mak, ...

Well, perhaps in the next millenium.

Anthony