and http://forums.dpreview.com/forums/read.asp?forum=1036&message=37324270
For easy comparison, I've direct linked the samples. Note that the 645D samples are cropped 100%, whereas all other are resized to match the same size:-
Set One:-
| 645D + 75mm |  |
| M9 + 50mm Summilux |  |
| 5D II + 50mm L |  |
| K-5 + 35mm FA |  |
| K10D + 35mm FA |  |
Set Two: (Test and resizing were re-done for the K-5 and M-9 (only) owing to the poor result of the K-5 above. A guessed reason causing which is the out-focusing of the first K-5 picture.)
| M9 + 50mm Summilux |  |
| K-5 + 35mm FA |  |
Related:-
How AF Errors Can Decrease *Effective* Resolution?
Major Causes of Poor AF Reliability of Pentax DSLRs
Is the AF Accuracy of Pentax K-5/K-r Really So Bad?