Re: ATM The Glass Giant

[Anthony Stillman <atmer@flash.net>]

In a private communication, Stan Truitt has kindly kept me on my toes.

As he noted, the 200 inch Palomar three way convertable could in fact have
been an aplanatic instrument.  A Ross correcter is used at the prime focus
anyway, and were the primary a hyperboloid, the correction, with
appropriate modifications to the corrector, could have been superior.
Further, an aplanatic design could have been realized in both Cassegrain
configurations.

I must admit that I was remiss in under-emphasizing the value of the
aplanatic design to the professional community and, I overstated its
failings.  In retrospect, I did this as a result of a personal bias I have
against figuring strong hyperboloidal convex surfaces.  And, in an attempt
to stear other amateurs away from the nightmare.

Richard, you are correct, the 200 inch Palomar could have been better.

Humbly,

Anthony