Originally posted by normhead At least one lens that could be very slow to lock focus on a K-5 is much better on a K-3. The Sigma 70 macro.
HSM, and SDM lenses are about the same, and feel a bit slower than their screw drive counterparts at this points.
Your impressions are pretty much what I've seen as well, except for HSM (but on a very different lens).
It was too windy here yesterday for the birds to perch on their favorite bush in our yard, but I tested the Sigma 50-500 OS out on the (empty) bird feeder, then on the closer porch rail, then the back shed, then back again. Compared to the K-5, the K-3 made the HSM of the Bigma feel noticeably faster going between these points, and didn't hunt at all in the overcast light. The DA*50-135 is just as pokey as before, and I can't tell much with the DA Limited primes, since they are all pretty fast focusers (small throw, light body), except the 35 macro, which seemed faster when going "all the way out and back" (ah, no focus limiter).
Quite happy with the AF in the K-3. On Halloween night it did a yeoman's job in "unavailable light" photography!