Using some spare parts I’m cobbling together a motor and belt system for autofocusing with old Pentax SLR lenses. I plan to use a robofocus motor and timing belt to focus the lenses (55mm and 135mm). For anyone using a similar system, how far does the belt need to move physically around the lens for autofocus? Does it need to make a complete revolution or does it just move a little bit back and forth? What is your step size and how many data points do you use?
And if anyone has some pics of their setup I would be glad to see it.