Hi Thomas,
These are my thoughts on the matter, and I am no lens testing expert, so
take them for what they are worth. It is not uncommon to find that lens
performance suffers at wide open apertures. Most lenses work best when
stopped down a bit. For example, the advantage of a fast lens (f2) over a
slower one (f4) is that the faster one begins to resolve better at a faster
aperture (f2.8-4) than the slower one (say, at f8). The very best lenses
often do deliver top performance wide open, however they should considering
their price tags.
To me, there are many more important factors within lens performance than
sheer resolving power. High contrast is the first that comes to mind. For
longer lenses, the quality of its bokeh is another. The range of its "sweet
spot" is yet another. I'd prefer a lens that delivers its best performance
over a range of apertures as opposed to simply at, say, f8. The size of the
lens is also important as I carry a backpack load into the field and often
attempt to swap lenses with one hand (not recommended without considerable
practice over a soft cushion).
There's been a lot of list talk over the past few days that question the
abilities of some Zuiko lenses. While I believe that it's possible for some
dogs to have escaped the factory, personally, if I questioned the results of
one of my lenses then my technique would be the first thing that I would
scrutinize. Did I use very slow, fine grained film? Did I use a sturdy
tripod? Did I use a lens support? Mirror and aperture pre-fire? Proper
exposure? When I look at a disappointing result, I can always answer "no"
to at least one of those questions. If the day ever comes when I can
consistently answer "yes" to all of those questions and still not be
satisfied with my results then it will be time to dump my whole OM/Zuiko
line up (and 35mm altogether) and move up to large format.
Take care,
Bruce
Bruce Hamm
Ottawa, Canada
bhamm@xxxxxxxx
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