On Fri, May 21, 2010 at 9:10 PM, Anthony Farr <farranth...@gmail.com> wrote: > On 22 May 2010 10:04, Adam Maas <a...@mawz.ca> wrote: >> >> Actually, it's pretty clear, neither AF or OS will function on bodies >> which don't support SDM (IE the K100D and all earlier bodies). HSM is >> merely Sigma's version of SDM and the OS system is integrated with the >> AF system in most lens-based implementations. >> > > Thanks for the clarification, Adam, that makes sense now. Pentax SDM > signals use the old Powerzoom contacts, right? But that doesn't mean > that a Powerzoom capable camera can control SDM, or the piggybacked > OS, where they don't have a controller for those systems, so > Thibouille's statement falls down on that point. > > OTOH, and IIRC (sorry, Mr Brewer) it took years for the protocols of > all the KA contacts (and variations) to be deciphered, and Pentax was > only telling service people. It's always possible that there are > undisclosed protocols awaiting future products, and that SIgma has > found and tapped into one of them. After all, how on earth can a > Pentax control in-lens shake reduction when its native SR is in-body? > Either these lenses have internal shake sensors and only need power > through the mount (which makes Thibouille's statement feasible), or > the Pentax bodies are also supplying shake data through the lens > mounts. It has to be one or the other, there can be no free ride. > > Just speculating. > > regards, Anthony >
The body doesn't control the OS system, just the AF system (which is a SDM clone from the bodies perspective). The OS system is controlled by the lens CPU, but relies on input from the AF system for some items (mostly when to lock on I suspect). The accelerometers used by the OS system are in the lens. -Adam -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
