Originally posted by AntonioS My previous Canon lenses also had front/back issues but nothing like large correction numbers I see with Pentax with some people setting to -10 and up !!!! This is crazy.
PDAF is not the 100% accurate focussing tool many folks thought it was. It was only as sensors beefed up their MP count this became apparent. Manufacturing tolerances mean that some adjustment is needed or desirable in some cases. I for one am very happy that Pentax along with other manufacturers provide this option. + or - 10 is not crazy, it is simply within the allowable user adjustable range. Unless someone has done very scientific testing who knows whether a Pentax +10 is any more of a physical adjustment than a Canon +5 ?
If you do have a camera that requires an adjustment at the limits and are concerned you are free to send it back to Pentax to have it adjusted under warranty so it requires zero adjustment.
My K1 is now 2.5 years old and the adjustments I need (+8 on average) have not changed at all over that time. So it is a one-off adjustment then you are good to go for the life of the camera.