The Nikon Model S-Series microscopes were the iconic microscopes from the 1960's, with state-of-the-art optics and mechanics. They are beautiful works of engineering, and pristine examples can still fetch moderate prices today.
The only one I have is a very unique example, which I have never seen metioned anywhere. It is a trinocular S-Series with vertical illumination mounted on a boom stand. It will experience too much vibration for very high magnificaiton work, but it is very nice for 10x and less work.
Robert Pavlis has a very nice write-up about the S Series.
for navigation!