Originally posted by JohnBee Wouldn't the fact than an AF lens be spot on, go to show the AF is calibrated?
The wonders of consumer-level production tolerances and quality control mean that it is not possible to have
one AF calibration for all lenses.
That's why Pentax cameras allow individual AF adjustments for individual lenses.
If all your MF lenses FF (via the AF confirmation) by roughly the same amount, it could mean that your camera needs an overall adjustment (but you then you should observe an overall bias required for individual AF adjustments).
Have you ruled out the influence of low-light / yellowish light? AF confirmation on the K-5 will suffer from the same FF issues that plague its AF performance. I recommend bright daylight for your tests.
Note that the AF confirmation window is a bit large. Try to approach the point of making the AF hexagon light up from both infinity and MFD. You should see a slight difference in where the focus ends up.
I use AF confirmation for MF lenses on my K100D all the time and it works like a charm. Maybe some practice helped, I think I'm better now at hitting the mid-point of the range when the hexagon lights up.