One of the weirdest lenses made, the Minolta 40-80mm f/.8 Zoom used a gearbox-like arrangement on the side of the lens for zooming and focussing. This is pretty much the only lens that used this arrangement. LensRentals.com did a tear down of this fascinating Rokkor MC lens. After opening up the lens and looking at how the lens focussed and zoomed, in their own words, "This is an intense little mechanical computer."
The report comes complete with an optical testing section, which provides a set of nice results for a 40-odd year old lens. While wide open at 40mm to stopped down to f/5.6 at 80mm, the testers pretty impressed.
Minolta was pretty innovative it its heyday, and this is just one example of that.
