The Hopewell Observatory (in Va) has a classical 12" Cassegrain optical tube and optics that were manufactured about 50 years ago and were originally mounted on an Ealing mount, for the University of Maryland, but they discarded it during the 1970s or 1980s and it eventually made its way to us (long before my time with the observatory).
The optics were seen as rather disappointing, and a cardboard mask was made at one point, to reduce the optics to about a 10" diameter, but it apparently didn't help much. The OTA was replaced with an orange-tube Celestron 14" SCT which works reasonably well.
Recently, I was asked to check out the optics on this original classical Cass, which is supposed to have a parabolic primary and a hyperbolic secondary. I did Ronchi testing, Couder-Foucault zonal testing, and double-pass autocollimation testing, and I found that the primary is way over-corrected, veering into hyperbolic territory. In fact, Figure XP claims that the conic section of best fit has a Schwartzschild constant of about -1.1, but if it is supposed to be parabolic, then it has a wavefront error of about 5/9 lambda.
I have not yet tested the secondary or been successful at running a test of the whole telescope with an artificial star. For the indoor star test, it appears that it only comes to a focus maybe a meter or two behind the primary!
It had a very interesting DC motor - cum - potentiometer assembly to help in moving the secondary mirror in and out, for focusing.
My question is this: Has anybody else done any optical testing on these classical Cassegrains by Ealing et al?