just read thru most of this thread and the previous thread....and *phew* i thought i was going crazy! i got the K-5 back in december....and well, when my tokina at-x 28-70mm f/2.6-2.8 or at-x 80-200mm f/2.8 is mounted...there's inaccurate autofocus. at first i thought it was simply a good sensor showing issues with my non-pentax and rather old zooms (they were bought circa 1999). but i have always had really nice and sharp pics when i shot with my old film bodies (PZ-1p, PZ-1, MX). of course i manually focused on those bodies (PZ bodies could do AF--and they were accurate, but really slow compared to other DSLR, like say a Nikon F100) anyways i went back to manual focusing at wide open aperture on my K-5. sure enough the pics were sharp!!! so that lead me to the fine adjustment option. i was still not satisfied.....and well, my craziness has lead me to you fine folks talking about this. well, i'm quite disappointed. not only is my K-5 afflicted with the 'string of pearls' stain, but now it's focus is just bad. what to do? it also does pretty bad focus in daylight too. for now, i've given a +2 adjustment to sharpness and have put -6 fine adjust; plus i tend to stop down to at least f/5.6 outdoors (but this is terrible, given i have f/2.8 zooms), and indoors, well, i'm going back to manually focusing (not too bad, but sheesh, i paid how much for this body???
) a last resort is to use the unsharp mask in photoshop--if i am really keen on saving a pic--but that's such a chore if doing to many photos. i do hope that a firmware update is available to alleviate this problem of focusing. i know i will return my K-5 sometime soon to address the sensor issue. until then, i'll just learn to live with the issues, and hopefully work around them. oh btw, thanks to all for your input, i really appreciate this forum
cheers,
raph