I was thinking the same things as Winsor and your reply. Is the test
setup really right? Is the camera body OK?
Also, how do you define "very sharp image"? To try to define it in terms
of lppm without any referrent to what that means relative to the visual
experience of viewing your prints and slides is just borrowing trouble.
If I have a lens that my experience tells me produces very sharp images
and I later test it, only to find that it doesn't have the performance I
expected on a particular test criterion and under certain test
conditions, is it suddenly not very sharp anymore? Are all those nice
sharp images I liked suddenly no good?
Moose
Winsor Crosby wrote:
<>
HOWEVER, if it is SO difficult for me to obtain a very sharp image on
fine-
grain 50 ASA slide film when the camera is weighted firmly on the
floor and
the mirror-up & pre-fire aperture routine is done (even if the
two-dimensional
plane subject is slightly off parallel), what chance of getting a
sharp image
with a hand-held camera and a subject that is three-dimensional?
Brian - somewhat puzzled on this topic as usual.
Only macro lenses are designed to have perfectly flat fields. The
center and the corners of the film plane have different focus points
with an ordinary lens, but the center is usually the sharpest. If
your best focusing efforts produce sharp corners and soft
centers(sounds like a chocolate) your focusing system may be off. The
camera may need servicing to make sure a focused image on the focus
screen corresponds to sharp center focus on film plane. The angle of
the mirror could be off. And other things I do not know about. It
would explain the soft slides overall as well if a carefully focused
viewfinder is producing a focused image in front or in back of the
film plane.
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