this is a great project...I finally retired from my job as an embedded systems programmer and have been eyeing up my old newtonian..an autofocuser looks like it might be a great start project. I was always hesitant about using the arduino, guess it was just an unfounded bias by those of us who who felt we had to start from scratch..but since playing with the arduino and raspberry pi I decided life it too short to keep redesigning hardware...lol...so plans are a small stepper on the focuser knob, some sort of arduino, and a control cable to start, maybe go wireless later. I'll keep you posted.. Brian K9WIS