Yes - they just supply power. All the time. It's not switched. As long as the camera is turned on, there's power available. As they don't also send the "change the focus" commands over the digital command channel, nothing else happens. There's no risk.
On Thu, Aug 31, 2006 at 03:46:06PM -0500, Gonz wrote: > I think you missed the point actually. Yes, they are power pins, but > the new lenses are going to share those contacts with the old power zoom > lenses, and the new camera bodies are going to share the pins with the > old PZ camera bodies. The new camera bodies might have to support the > old power zoom lenses, or they might choose to ignore it. The bigger > problem is what do the old PZ bodies do with the new USM lenses. Do > they just supply power to them John and hope for the best? I dont think > they will risk that scenario. > > > [EMAIL PROTECTED] wrote: > > > > 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. > > > > It's just like that power supply box in your PC. You can use it > > to power a hard drive, a CD drive, or any other peripheral you like. > > All the control signals go over a completely different path. In the > > case of a Pentax camera and lens (KAF or later, naturally) that's > > the digital signal pin (the one that isn't there on a KA mount). > > You don't need any new pins - a digital messaging protocol can > > be extended to new message types very simply. > > > > If a lens gets a message it doesn't recognize, I would expect that > > it just ignores it. > > > > > > On Thu, Aug 31, 2006 at 02:13:43PM -0500, Gonz wrote: > > > >>I would imagine they would do something that would prevent that. I.e, > >>I've seen similar situations where they do something simple like switch > >>the signal polarities or provide some type of pulse modulation or high > >>frequency signal. > >> > >>[EMAIL PROTECTED] wrote: > >> > >>>I would hope they would work as manual focus lenses. It that's true, > >>>they should work on old bodies. Given the proclivities of people to thy > >>>things that physically work, I hope you can't damage a USM lens or PZ > >>>body if they are mated with each other... > >>> > >>>Kostas Kavoussanakis wrote: > >>> > >>> > >>> > >>>>On Thu, 31 Aug 2006, Sylwester Pietrzyk wrote: > >>>> > >>>> > >>>> > >>>> > >>>> > >>>>>Exactly. One must have lenses with built-in USM motor for USM to > >>>>>work :-) But I guess new mount would be back compatible, so older > >>>>>lenses would work the way they usually did ;-) > >>>>> > >>>>> > >>>> > >>>>Would the opposite also be correct? Would USM lenses work as AF lenses > >>>>on screw-driver bodies? Would they even work as MF lenses? > >>>> > >>>>Kostas > >>>> > >>>> > >>>> > >>> > >>> > >>> > >>-- > >>PDML Pentax-Discuss Mail List > >>PDML@pdml.net > >>http://pdml.net/mailman/listinfo/pdml_pdml.net > > > > > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
