If the problem was a centering defect, it should be consistent. How does it perform wide open? I'm surprised you're seeing any softness at f8. How about the camera your testing it on? Are you sure you don't have a mirror box problem? Have you tested other lenses on the same camera?
I'm don't want to be a contrarian, but the inconsistency of the problem suggests it's not a centering defect. Of course I could be wrong, and I frequently am. Paul On May 23, 2008, at 5:38 PM, Mark Erickson wrote: > I recently received my DA* 16-50 F2.8 back from Pentax USA (via > California > Precision Service). It had a clear centering defect that yielded > softness > on the right side of the image. > > First thing I did when I got it back was to onto my "lens test > range" (a > tripod and a couple of test patterns taped to the wall). > > Two different pictures, both taken at 50mm and F8. One is sharp in > the > center and left and soft on the right. One image is sharp on the > center and > right and soft on the left. And now the SDM autofocus doesn't work. > > Seems to me that the lens has some kind of fundamental mechanical > instability (separate from the now-defunct focus mechanism). > > It's going back to Pentax USA, but I'd say that my confidence in > this lens > is pretty much destroyed. Anyone out there care to commiserate? > > Disappointed, > > Mark > > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above > and follow the directions. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
