Telescopes (The SydUniPhys Connection)

My memory was jogged by the anticipated hot-air balloon story and the assistance of our very own workshop chaps. I guess sufficient time has passed so I can safely mention the workshoppers and the ... ahem ... "foreign orders". However, it must be stressed that these were definitely of a scientific-engineering nature as could be reasonably expected from a then fully taxpayer-funded academic institution. Seriously, that's my opinion. My own foreign order concerned optical telescopes, and the assistance was most gratefully received scientifically - OK it was my hobby.

The background is that from the late fifties I was fascinated with telescopes. My first experiments were with lenses from a local optician and cardboard tubes. Needing to max magnification I tried a 2-metre focal length lens (0.5 dioptre, if you've forgotten Phil Guest's lectures) mounted in a cardboard tube. The chromatic and spherical aberration was terrible and even worse was the mechanical stability of mounting and pointing.

Anyway, I progressed to reflectors. Next was a Newtonian with a 6-inch parabolic mirror. That required some delicate polishing from a spherical surface. Depositing a reflective silver coating on the main mirror and the optical flat was interesting - also it quickly tarnished. Esdaile's in Sydney in those days had someone do aluminium reflective coatings and that problem was solved. The whole thing was mounted in a rickety split drain pipe with various Heath Robinson plumbing components and a counterweight. Mechanical stability was the main problem, and that's where our workshop came in. I scrounged some beautifully made Aussie WW2 brass things from those Army Disposals shops which were around in the city in Sydney in the sixties. I forget what they were called and I think they came from field gun optical sights? They had a full 360degree scale with a vernier and that's what a telescope needs. I wanted to make an equatorial mount to follow the celestial objects, where an ordinary 2-axis mounting is in turn mounted on a wedge with the angle of the geographic latitude (ca 35deg) and aligned geographic north-south along the wedge. Then one axis is for the right ascension and the other is the declination. My design needed brass pipes and a counterweight, so I went down to the workshop to scrounge some nice brass bits and to start using the lathes - "NO WAY PARKO"!!! However, being such nice chaps they decided to do a foreign order (I think it was foreign order night) and they did the whole construction to my design, including matching up the various threads. It was a fabulous job, and there was no way this simple amateur could have done any of it.

I used the 6-inch Newtonian for some years on and off, and even attempted celestial photography by slowly turning the right ascension knob to track the object through the finder. Hard work, especially in the middle of a Sydney night. After that, I invested in a professionally made Celestron 8-inch Schmidt-Cassegrain telescope, which has a motor drive on the right ascension to track the celestial objects in the night sky. It was imported from California by a school teacher who decided to become a dealer and make money from his astronomy hobby. I still have the telescope, now along with a smaller Maksutov-Cassegrain sourced from Asia which is suitable for terrestrial viewing. From the sixties there was a huge growth in local astronomy hobbyists. These days there are two big US manufacturers Celestron and Meade, plus some from Asia now - especially for achromatic primary lenses. The competition between Celestron and Meade is intense and these days their Schmidt-Cassegrains are fully computer-controlled and with even bigger primary mirrors so that you need to build a backyard observatory dome. I can only dream.

--TonyP