I've had the K10 for almost an year and it's been pretty good. I've used it with the kit 18-55 lens, tamron 28-75, the 100mm macro and pentax 70-200. Sometimes I noticed that in some images the object was out of focus but blamed it on my mistakes.
Today I got the 16-46/4 lens, brand new from amazon, and did some test shots of my son. They seemed kinda soft on the camera preview, so I downloaded them and sure enough - they were out of focus!
This was only visible at 16mm, at 45 it was OK.
Long story short - after downloading the focus chart I did some tests and now I'm confused.
With K10 the 16-45 is spot on at 45mm and waaaay off at 16mm - heavy back focus.
With K10 tamron 28-75 is spot on at 75mm and so-so at 28mm - slight back focus also.
I have DL too, so I did a test with that one too. It focuses correctly at any range.
Is this something common with K10 - back focusing at wide angles?
Should I send back the lens and hope that the next one will be OK or should I send the camera to Pentax for calibration? How long does it take to get it back - I have events that I have to cover next month.
I was really looking at D300 and now this problem is adding more weight in that direction.
Here are some pictures:
All shot at f4.
K10-pentax45mm
k10-pentax16mm (crop)
K10- tamron75mm
k10-tamron28mm
DL-pentax45mm
DL-pentax16mm