> Hi Roger,
> Is the RoboFocus anything more than a server or stepper motor hooked up
> to the focusing ring/knob of the scope?
> I had a look at the RoboFocus website and it seems, from the pictures
> and brief descriptions, that they have simply built a bracket and then
> used a belt to link the motor and the focusing together.
> If this is the case, then building one might be something that's very
The standard unit is a stepper, with a massive reduction gearbox
(typically about 50:1), and a simple serial command interface. It contains
some perhaps important 'extras' in the code, when controlled from the PC,
in that it will always finish movements in the same direction, to
eliminate backlash in the system, and programmed with focus positions at a
range of temperatures, can automatically shift position to correct for
My version, emulates the standard unit, but adds half stepping for the
motor (making it smoother), and uses a USB interface instead of serial.