Hi Ed, Checking for a flat field of focus is most critical with this lens. Square it up about 6 feet in front of a brick wall with the camera on a tripod. Shoot wide open (f2.8) at 50 mm focal length and again at about 24 mm. Check your results at 100 percent on a computer. Focus should be equally sharp top to bottom and left to right.
Paul via phone Paul via phone > On Feb 18, 2016, at 2:56 AM, jtainter <[email protected]> wrote: > > > I'm itching to pull the trigger on the 16-50, it's a little higher > than I want to spend, but I might be able to convince myself to do it. > > My questions to PDML... > > Since I can physically handle the lens and take test shots with my own > camera, what am I looking for? Is there a set of shots I should take > to test the lens? What am I looking for in a used lens? > > Thanks! > Ed > > Ed, do a rigorous brick wall test across the zoom range. This lens often has > optical decentering. I had two bad ones in a row. > > 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. -- 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.
