In article
(Refering to a Pop Photo article refering to their lens tests:)
>I think they did, in the 1st "SQF" lens testing article. I don't
>remember the numbers, but they were of the order of 60% center, 30% >edge, 10% corner.
I think I had better avoid jumping into this discussion, except to
note a preference: If those percentages are how Pop Photo weights
the numbers to arrive at a single number, I would consider the
posted test results useless. To me, if a lens cannot produce sharp
images over virtually all of the film frame at most apertures, it
is not a sharp lens. Using the above weightings, a lens could be
really superb in the center and really terrible near the corners
- and have a good rating! Most lenses at most apertures do perform
reasonably well in the center - it is edge and corner performance
that separates the unacceptable from the good lenses that I would
prefer to use. If only one number is to be used, maybe the center
should be dropped (it is likely to be better than the edge/corner numbers), and an average of the edge and corner numbers should be
used - otherwise, a lens that gets a good rating may be useful only
in the few situations (for me) where the part of the subject that
needs to be sharp is near the center of the photo, and the rest can
be garbage. To me the subject photographed is everything inside the
frame, not just the tree or animal, etc. that the lens is aimed at
- and it all needs to make sense, and be rendered appropriately
for what I am trying to do with the image. I do not want a poor
lens determining that all the corners of all my photographs are
always rendered softly - I may want to make other choices.
Hope this helps.