gfen wrote: > I was under the impression that IS patents were put out by Pentax many > years ago, and further more that the current IS and VR lenses were based > on these patents?
Pentax put out their first IS patent in '89, 90 or 91 (I don't remember). They are the oldest patents I can find on working lenses, as opposed to just construction principles. Canon early patents (earlier than the Pentax ones) just refer to the servo mechanism and the fact that you needed moving elements and correcting elements. The Pentax patents are complete lens designs on IS lenses and all subsequent Canon and Nikon IS patents refer to the Pentax patents. Who patents what from whom will be pure guesswork for any of us. There are several possibilities 1) they license it,. 2) Pentax did the developing work for another company (Canon). 3) Nikon and Canon have found away around the Pentax patents. Incidentally, Nikon VR(IS) patents seem to rely almost exclusively on Pentax and Canon patents. The only thing Nikon seem to have original, and this is debatable too and need closer scrutiny of the patents as Pentax have similar claims, is the extra stop of leeway Nikon claims for their IS compared to Canon's. This has to do with how the IS behave when the moving elements are close to, or at their max moving distance; the Nikon (and Pentax) way is more "intelligent" IS. All this from memory. There could be some error. Anyway, the interlocking patents are extremely complex; both Olympus, Fuji and Minolta have filed IS patents as well. It is interesting though, that Pentax have fully intergrated IS and USM into the K-mount while maintaining full compatibility. This is not just a bunch of patents, but a complete working (K-mount) system. But this is nothing particularly sensational. Just because the engineers have fully working USM and IS lenses in the lab doesn't mean the beancounters give the go ahead. Pål
