ATM Forever dreaming : What to do with a SHORT focus spherical mirror?

["Bevan HARRIS" <BMH@bigpond.com>]

Hi all,

I've been subscribed to the list a little while now, so I guess it's about
time I made myself known.  I'm trawling around for ideas of what to do with
an 8" f2.0 spherical mirror that I have had stashed away for like, years.

I originally bought the mirror in the guise of an almost complete lensless
Schmidt camera (so it includes a matching cut film holder) from another
member of my local astro society, with the intention of piggybacking it on
my DS16.  Life (marriage, moving, work, study... you all know the drum) has
unfortunately taken it's toll on my scopes, so that most of my observing
these days is done with a pair of 10 x 50s and an Astroscan.  The DS16 has
no tube or mirror cell, and I'm involved in a passionate hate affair with
the German equatorial (it's been banished to various backyard sheds since
1991).  The lensless Schmidt exists only as the mirror and film holder.

As life always turns full circle, I'm now returning to a point where I can
rebuild my astronomical stocks, so to speak, and have been thinking of what
to do with the 8-inch.  I guess the crux is, do I want a visual or a
photographic instrument?  Rebuilding it as a lensless Schmidt is
undoubtedly the most pain-free solution, but I'm interested in just what
sort of visual scope could be built from it.  

My general thoughts are revolving around a Cassegrain/Gregorian with a
Nasmyth focus (as there's no central hole).  I'm looking for ideas and
advice on how I could best achieve this.  One design that I've seen which
holds some attraction is the Sigler Relay Telescope, first proposed in the
article "All-Spherical Relay Telescope"  in TM2.  I don't know if the SRT
can be effectively adapted to what I have in mind, given the speed of my
primary and the (comparatively) shorter back-focal distance of a Nasmyth
system.  I'm also considering appropriate variants of the
Schmidt-Cassegrain and Maksutov-Cassegrain.

A further idea I'm toying with is to build the scope in a modular fashion
so that a variety of "top ends" can be mated with the primary sub-assembly
and mount.  I'll freely admit that I may be biting off more than I can
chew, but I'll never know if I don't give it a go, will I?

I'm trying to expand my minimal knowledge of optical theory and have also
obtained a couple of optical design programs in an effort to answer some of
these questions for myself.  Whatever design is eventually considered
feasible needs to take into account that I'm a complete newbie when it
comes to pushing glass.

So far as text resources are concerned, I have ATM 1,2&3 (Ingalls), How To
Make A Telescope (Texereau), a full set of Telescope Making and most issues
of Sky&Telescope and Astronomy since 1981.  Additionally, I have access to
a comprehensive astronomical library.  I'm currently reading the book
"Elements of Modern Optical Design" by Donald O'Shea (1985).

If this inquiry is familiar to anyone, I posted a similar question to s.a.a
in early April.  The advice I received was:

a) Subscribe to the ATM list (I've done that, haven't I?)
b) Make a corrector for a Schmidt camera
c) Sell the mirror

Any suggestions or advice would be much appreciated.

Clear skies!

Bevan Harris (31º52'23"S 116º02'22"E)