>>> >>> >> As I asked elsewhere, would there necessarily be any extra circuitry in >> the lens? Or any need for additional signals? [ ... ] >> > > USM, at least as implemented elsewhere, uses a stepper-type motor which > is controlled by in-lens circuitry, not the camera body. Sort of what I thought (I've never been bothered to check closely.)
But like I said, surely you might instead put the stepper in the lens, but the controller in the body? Again, I think that would require 4 power lines to the lens instead of two. Also, *if* the main object is to reduce the amount of mechanics between the motor and the moving parts, a "normal" electric motor might still be used. > The camera > tells the lens how far to turn then the lens does so. This requires a > level of in-lens circuitry beyond what is currently there (and is the > reason for the problems with Sigma lenses and newer Canon and Nikon bodies). > > -Adam > > > > -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
