Microscope 216 Fine Focus Mechanism
Fine focus is a thumbwheel/fine-pitch screw that moves the coarse focus mounting block up or down relative to the main body support.
A: Fine focus racked all the way up
B: Fine focus all the way down.
Fine focus slides body mounting plate "B" against support "A" using a fine-pitch screw thread.
Coarse focus slides body tube "C" against dovetail machined in plate "B" using spiral rack and pinion.