If anything happens to a lens to decenter the elements, wide open
performance may falter. Any lens that can only get a C SQF grade wide
open will be harder to focus than one with a higher grade.
I can predict a lens that will be C or worse wide open by the image I
see through a Varimagnifinder at 2.5x and on an all matte screen. But I
can't predict a B vs. an A grade. Said another way, for critical focus
ability, one needs a lens capable of B- or better wide open. Less than
that and critical focusing is guess work.
Gary Reese
Las Vegas, NV
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|