On Thu, Feb 4, 2010 at 10:13 PM, Anthony Farr <[email protected]> wrote: > Yeah, I understood that ring motors were applied in a "direct-drive" > configuration, and that USM micromotors, the rotating types, were used > as an alternative to and in the much the same way as conventional > motors. But rotating USM motors aren't all just high frequency AC > electric motors, they can be a pure USM system where the "slider" of a > linear or annular motor is in the form of a rotor that is spun by the > "stator" when it produces a wave of ultrasonic vibrations. Which > types of motor are in what brand of lens....... I don't know. > > It was the third possibility that I was unsure of. That is, if any > lens used linear (ie straight not ring or micro) USM motors that > simply moved back and forth through a limited range and moved the > focusing group directly. If any lens had such a motor, I wondered if > it would have the power to do the job in direct-drive configuration, > or if it would need to work through a gear-train. > > I'm not the gearhead that I once was, who knew the specs of every > camera in the stores. The insides of most cameras these days are a > complete mystery to me. > > Life's simpler that way :-) > > regards, Anthony >
I'll admit my interest here is primarily professional, not gear-geeking. I'm currently working on my B.Eng in Electrical Engineering and this is one area that's particularly interesting to me. As far s I'm aware, micro-motor USM is not using true USM motors, mostly for cost reasons (the main reason wht Micro-motor USM was introduced in the first place). A linear motor would be very interesting in a camera application, I suspect some electronic aperture systems may use them, and wouldn't be shocked to hear that they were being used for In-Body IS, but I doubt they're being used for focusing since you still need the helical for manual focus, although 4/3rds or Micro-4/3rds could as Panasonic and Olympus use focus-by-wire (as does Canon on a couple lenses, the 85L most notably). -- M. Adam Maas http://www.mawz.ca Explorations of the City Around Us. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
