Hello ladies and gents,
I stumbled upon this very light, and seemingly well-machined mount, with belt-driven slow-motion controls. The given payload seem a bit optimistic, though.
With 4" bearings: http://www.herculesoptica.com/4.html
With 2.5" bearings: http://www.herculesoptica.com/25.html
Has anyone ever tried one? I'm tempted to experiment with it with my 4" f/7 frac.