I consider 9019284 a good copy (Got it from Adorama). Having said that i shot all day at a -5 AF adjustment on the K20D, and based on results thought i could get closer, -7 shot under artificial light at ISO1600 seems about as spot on as it can get, will need daylight to verify.
Based on how this went i will retest the 40/2.8 as well since i stopped at -3 there and seeing how i thought -4 was it for the 16-50 i may not be spot on. (Test charts would tell me i back focus already, real use shows i am on at -7 a little in front at -5)
I need to find that one chart again that you mount at 45 deg and has a target parallel to focal plane, that way no matter how off the focus point is from where i think it is, it won't be causing any kind of skew. Any time we focus on a 45deg plane, the amount the center focus point is off from the center in the viewfinder will skew the result.
If all my lenses keep coming in at -7 i may need to ask Pentax to tweak the body or i soon run out of wiggle room with -7s everywhere
I'm just glad i have the capability at all.