My gear came back from Pentax--K20D, DA* 16-50 and DA* 50-135. Turnaround was just over three weeks, but it took me nearly another full week to pick up the package after UPS messed up the delivery.
I sent all this stuff in because on the K20D the DA* 16-50 would not autofocus to infinity at 16 mm. It would focus only to about the 2 m mark. From 18 to 50 mm it focused fine, and focused fine at all focal lengths on my K10D. So now the focus problem seems to be solved. It focuses to infinity at 16 mm. What was wrong? Can't tell. The work order came back with some gibberish stating that they "repaired or replaced" various parts in the lens and/or camera. I can't tell exactly what they did. I sent in the DA* 50-135 because adjusting the focus at 135 mm caused it to focus beyond infinity at 50 mm. The work order came back with these instructions: "Please set focus shift adjustment to where it will focus at medium setting of the zoom range." So this is Pentax's official instruction for how to adjust focus in a zoom lens. Over at dpreview, John Cunningham of Pentax USA has posted essentially the same instructions. I interpret this to mean that one cannot adjust a zoom lens to autofocus accurately across the whole zoom range. This weekend I'll try to test these lenses again for focus adjustment. Joe -- 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.
