I doubt they do refocus and you are right -- any lens its going to have its edge
MTF performance cut down dramatically if their is field curvature. I always
find
curvature of field an interesting thing as unless you are taking a picture of a
flat wall
then your not going to notice it because in fact there will be SOMETHING
in focus as the edges of the field. Its just that those objects will not be in
the same plane of what is in focus in the center of the image. For most images,
that doesn't matter.
Mark H.
> I also agree MTF is a very useful tools and the charts are much more
> useful then the overall rating. bUT I have one question, does any one
> know how Photodo check the MTF of center and edge? what important is
> will they refocus on the edge before they take the reading? If a lens
> has high field curvature then the edge MTF will be very poor (because
> you focus only at the center) but the real picture on the field may
> not be that bad.
>
> The Leica M 50/1.4, 35/1.4 and 75/1.4 were tested to be having very
> high field curvature by Popular photography, the SQF were very low at
> F1.4 and F2.
>
> C.H.Ling
>
< 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 >
|