JMI MotoFocus+ William Optics Rack-and-Pinion Focusers – Config. 9 Focusing is made easy with JMI MotoFocus – William Optics Rack-and-Pinion Focusers – Config. 9. MotoFocus is a battery operated hand control with an electric focus motor that attaches to the shaft of a focuser knob (or the knob itself) for precise, vibration-free focusing at high power without the need to touch the telescope. MotoFocus is great for visual and photographic use and features variable speed for coarse and fine adjustments. Precise positioning is accomplished through electronic braking. Mounting is easy and requires no drilling or tapping. Compatible with William Optics Star 71 Focuser.