William Robb wrote: > >> Joe, I think you ran the test backwards. Depth of field is not the >> issue, depth of focus is. As focal length extends, depth of field >> decreases, but depth of focus increases. Try calibrating your 50-135 at >> 50mm, and then see how it does at the long end. I am starting to think >> that my long time eschewing of zoom lenses may not be such a bad thing >> though. >> >> Not following, Bill. At 135 mm the lens definitely was improved by a -4 >> AF adjustment. So if testing at some other focal length gives a >> different result, I will have soft images at 135 mm. > > That doesn't necessarily follow.
Bill's right. As he said, depth of focus increases at longer focal lengths. -- 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.
