John wrote:
> I think Mike has come up with the best sig line ever for the
> discriminating equipment-enabled photo buff. Can I steal it?
It won't be stealing...it will be "helping disseminate the truth." Please
help yourself.
I'm sorry I don't have it to hand, but a few years ago I attended a talk by
Kornelius Fleischer of Zeiss in New York City, and he passed out a sheet
that listed "just some" of the various parameters by which lenses must be
designed, and hence must be judged. The list, as I remember, was 20+ items
long. The fact is that lenses can be judged by any number of different
specific technical parameters, and parameters which matter quite a lot to
one user may matter not at all to another. A few specific examples:
I photograph in available light, often using wider apertures, so very few of
my photographs don't include visible "bokeh-aji" (thanks, Take <s>) in them.
But my friend Ctein, who shoots with a Pentax 6x7 and makes 16x20 dye
transfer prints, was mystified by the early discussions about bokeh...and
soon discovered why. Going back over his life's work, he found extremely few
pictures that showed _any_ out-of-focus blur whatsoever. So I care about the
way lenses render out-of-focus areas, and he doesn't.
A lens for photogrammetry or architechtural photography needs to have as
little linear distortion as possible. A family snapshooter may care nothing
at all for linear distortion.
For a few years I worked part-time for a friend who was a staff photographer
for a large school system. He had a large equipment budget, and could buy
all the toys he wanted. His problem was _spending_ the budget every year.
This means he is unaffected by considerations of low price, which, according
to Fleischer, is one of the top two limitations facing camera lens designers
(the other is size).
The Pentax SMCP-A 35/2 has only one real weakness--occasional smearing of
the image in the far corners. Imagine a photographer who gets all his prints
made by a commercial photofinisher whose equipment automatically crops 30%
of the image area. This photographer never SEES the far corners.
Imagine a surveillance photographer who absolutely needs the utmost in
resolution--everything in his film choice and technical setup is calculated
to make it possible for him to read automobile license plate numbers from
great distances. Now imagine an art photographer whose "thing" is motion
blur--every picture she makes is made with low shutter speeds while she
purposely moves the camera.
Otto Braasche is a German aerial photographer who shoots out the window of
his plane with his lens wide open, at subjects which are often a quarter of
a mile away. Now contrast this with a tabletop still-life photographer, who
shoots exclusively with his lens well stopped down, at subjects at most a
few feet away. Will these two photographers share the same evaluation of the
same lens? Highly unlikely.
And here's a very simple example--professional editorial photographers who
shoot (and sell) slides are often vitally concerned about the color
transmission characteristics of a lens--cooler, warmer, more saturated, more
muted. I shoot Tri-X exclusively! You can imagine how deeply I care about a
lens's color transmission (not at all).
This list of examples could go on, and on, and on, and on. The fact is, all
lens tests are wrong because all lens testers make assumptions about what
the end user cares about--and those assumptions may, or may not, jibe with
what you actually care about and what you actually need. It's sometimes
possible to get information about lenses from tests, but generally the real
truth is what a Leica lens designer once told Arthur Kramer, who used to
write about optics for the old _Modern Photography_ magazine: "All lens
tests are inadequate shortcuts. The only way to understand a lens is to use
it for a year."
Especially, any system which pretends to reduce evaluations of lenses to a
single index--a 1-to-10 scale, a five-star system, whatever--is ridiculous.
One tester's five-star system may be heavily weighted for value--so a very
cheap lens that performs adequately may rate five stars, and a technically
superb lens that costs three times what its nearest competition costs may
rate one star. Another tester's five star system may not consider value in
the weighting at all, and those judgements would be reversed.
It's hard for some photographers to grasp, but any lens is a good lens if
_you_ like it, and if it is capable of giving you results that please you.
But you must have the courage to use your own eyes and make up your own
mind.
If you love a lens and some "test" says it sucks, who are you going to
believe?
All lens tests are wrong.
--Mike
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