Great. Thanks for the info. Do you know how to go about updating the Sigma firmware?

I used to have the K-5 but bought the KP in December. The Sigma 70-200 2.8 II Macro HSM doesn't seem to work with the KP. The KP goes really flakey, controls are sluggish, dials don't change the settings, AF doesn't work, takes a good few seconds to turn off. Does anyone know anything about this? Could it be firmware related?

Thanks very much for the quick replies. I did a quick test with the kit lens and that appeared to be back-focusing too. So I followed the instructions on the link from iceblinker and it appears to be focusing accurately now. Thanks again.

I've just started noticing that my FA 50mm lens is focusing about 5mm-10mm beyond the intended focus point. Has anyone experienced this sort of problem with this or any other lens? Does anyone know of a way to correct the problem other than the rather hit-and-miss solution of focusing on something closer than the subject? I shoot with a Pentax K100D.

Any comments or suggestions are gratefully appreciated.