Abstract: A rotary lens positioning mechanism with lens position feedback, in one embodiment, includes a worm-gear drive motor assembly, a Geneva gear drive assembly, a lens carrier disk, and a lens position feedback means. The worm-gear drive motor assembly includes a drive motor, which for some applications can be an N-scale model-train locomotive electric drive motor, and a worm pinion gear. The lens position feedback means, in one embodiment, includes two sensors each comprising an emitter-detector light-emitting diode (LED) pair, two reflective surfaces, and a computer. As the lens carrier disk rotates, the LED emitter of the sensor emits light to the reflective surface. If the light hits a reflective surface, it is reflected back to the LED detector of the sensor, turning that particular sensor on. The on and off signals of the respective sensors are translated into binary “words” to indicate which lens is currently intersecting the light.