>Would an incorrect lens flange-to-sensor measurement create the zone- >focus issue above?
Yes, precisely. From your description it sounds as if the adapter is too thick and is not quite reaching infinity focus. This can be masked in many cases because stopping down can extend DOF sufficiently to cover it. Magnification doesn't change with crop factor: Magnification is magnification it's approximately equal to the focal length of the lens divided by the focal length minus the distance between the object and sensor (M = f/[f-d]). The smaller sensor size of APS-C should give you slightly more DOF than you'd get with the same lens on full-frame, but in practice the difference isn't big enough to be noticeable unless you're shooting macro. -- Mark Roberts - Photography & Multimedia www.robertstech.com -- 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.
