The AF on my K-5 was way off in low light. Upgraded to latest firmware but it didn't help. I used it during many hours in a day for a wedding workshop, and it performed as expected in daylight, and after this, turned it in for repairs.
Got the camera back yesterday - was in town and had a long walk home. I noticed immediately the focus in bright/normal light conditions was off. Micro adjusting to the max wasn't enough. I had 3 lenses with me and same happened with all. One didn't appear to perform better than the other, but hard to say as the focal lengths were different, but again: overall very bad focusing. Completely unusable.
The sun went lower and lower as I was walking and I noticed how the back focusing shifted towards better accuracy. I never did enough testing in low light to validate the repairs. Didn't matter. The cam is practically worse than before now since I shoot more during the day than night or evenings.
Went to the shop again today - we tried their demo model and same problem! Back focus issue in bright light. They then opened another K-5 box - seemingly worked better but then I gave it a try (the shots taken didn't look convincing to me, but also not bad enough to convince the retailer). It too had problems.
Aimed the cam towards a bright sign approx 7m away and the focus was off by 1½ meters. I was able to manually focus more accurately. Yes, bright surfaces/targets, but it was not harshly reflecting light. Should have been piece of cake job. My K-x does a better job.
I had it for repairs for 5 weeks the first time and now it's back in for repairs again - we tried to see if they had another sample which performed as it should but nope. So this is the only choise. I have 2 weddings coming up within the next 3 weeks, so I'm frustrated about this. Not only because of the weddings, but the issues in genereal. I purposely delayed my K-5 purchase because I read about several issues. But then went ahead after more and more comments about the production being fine - and got me a cam with problems.. nice!
The shop are trying to collect a working sample for me - could be K-x, K-r ,K-5. Whatever, so I can borrow it. That's a big plus.
Oh, and they gave me a free t-shirt.. yey
Seriously though - very disappointed at the repairs of this thing. They seemingly fixed the issue - but created another.