> Yet another post that misses the most important point. > > Those two additional contacts are *power* contacts. That's all. > There's no signalling going on over those contacts, so there's no > need to play games with polarities, pulse modulation, or the like. > > They are there solely to provide power to electric motors; more > power than is needed for the CPU and other circuitry in the lens. > As I asked elsewhere, would there necessarily be any extra circuitry in the lens? Or any need for additional signals? Or might there simply be a plain, old motor control via the power alone. - And processing in the camera, based on encoder feedback from the lens. I think that's there already in the current AF interface, but I could be wrong.
I'm not sure what you are referring to when you talk about pulse modulation or polarities, but if you are thinking about step-motors, note that the ones I've programmed are actually controlled via the power input, too - but using 4 lines instead of just 2. And they are current-controlled, not voltage-controlled. I guess what I'm saying is that even if they put the motor in the lens, they might keep the motor's controller in the body - thus having no need for extra "messages" to the lens. - Toralf -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
