When I adjusted the focus on my K10D, I used the middle of the zoom range on my DA 16-45. I then checked both extremes of the zoom range on it, and on my 50-200, 10-17, and 24-90, and all were spot-on.
Rick --- Paul Stenquist <[EMAIL PROTECTED]> wrote: > That's good information. I had wondered at what > focal length the > focus adjustment should be set on zoom lenses. It's > obvious that it > wouldn't be absolutely consistent throughout the > range. But I would > hope it would always be close. My lenses seem to > show only minor > variation in this regard. > > BTW, my new DA* 16-50 is very nice. No problems. > Hope we all have no > problems going forward. > Paul > > On Apr 16, 2008, at 10:04 PM, Joseph Tainter wrote: > > 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 > > PDML@pdml.net > > 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 > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link > directly above and follow the directions. > http://www.photo.net/photos/RickW ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
