Originally posted by jay_akita That was a major concern of mine too - so far I've been pretty impressed with AF accuracy @ F1.4 & F2.0 so hopefully Pentax has improved QC to where it's not as big an issue anymore. Still need to do a formal focus test yet with AF charts but my initial impression is very good.
It is possible that the QC issues have been resolved, but I tested five copies of the DA55 in the Spring of 2011, which was well after Dpreview ran their tests, and none of the lenses was even close to acceptable. I used the LensAlign system to test focusing accuracy, but even simple shooting of ordinary objects at maximum aperture showed front and back focusing to occur almost at random. If you are shooting with the aperture stopped down, such focusing errors will not be noticeable, but then what is the point of having a super fast lens if you cannot use it wide open?
I realize that there are many satisfied owners of the DA55, but I think it is prudent for all those who purchase this lens to perform their own careful testing.
Rob