Hmmm.. weird
(please do not take this 100% into account, but), my K-3 arrived 2 days ago. I upgraded from a K-r that i still have. Very pleased with K-3 overall but
though i didn't do measured tests, one of the first things i checked was the AF system (Phase detection), compared to the old K-r (with the 50mm 1.8 and 18-55 kit lens) was the same to me, in terms of speed.
Indeed Contrast detection through Live view is very fast but i don't use Live view at all.
I repeat, in terms of speed, not accuracy and it was subjective real-world use assessment, not something scientifically measured, that's why i said at first take this testimony with a grain of salt.
Maybe this is related to the lens used, i don't know. I asked myself, what was i expecting, AF times to be cut in half?.. Hmm, maybe, or maybe K-r is not so bad in terms of Pentax AF speed
This was with camera firmware at 1.11, right out of the box. I have updated to 1.21 meantime but i don't think that had anything to do with it.
For me the low-light autofocus is fast but in this case in particular i was hoping to see a bigger difference compared to K-r. Ah (this is important), "low light" meant a 16 sq m room lit by two 12W led light, not really candlelight, true.