Originally posted by sterretje I don't think that there is any guarantee that it does or does not happen on another camera. Even if 20 (or 200 or 2000 for that matter) people report no issues, you might have it.
Personally I feel that Pentax should put user accessible AF adjustments in every model. For the entry levels they can limit it to a few lenses (e.g. 4) and for the (semi-)pro they can set a higher limit.
The second best option is to allow dealers to use the special software that seems to be required so if I buy a lens in the shop and I bring the camera in, it can be adjusted while I buy; maybe this option already exists, not sure.
My point was that early DA21s had a very specific issue on the K10D (there were endless threads on DPR about it in the past) - it wasn't just the usual variation you expect with a variety of lens/body combinations. Apparently Pentax sorted the problem in DA21s of later manufacture (or so the rumour goes). So my query was very particularly aimed at people whose DA21s behaved in this way - i.e. backfocusing at apertures up to f/5.6, and refocusing when reset to f/8. That's certainly what mine did on the K10D, and other people reported exactly the same thing. I was interested to know if lenses which had exhibited that behaviour, and had not been fixed or replaced by Pentax, did the same thing on the K-x.
Apparently later DA21s don't do it and I would totally agree with other posters that this lens plus the K-x would be a near-ideal combination for many things.
Incidentally, although I don't know if it applies to the K-x, service agents can make individual adjustments for specific lens models on the K10D - but I think they can only put a very limited number of lenses in the camera's memory, and it's not user-accessible even in debug mode.