No attempt to be contentious . . . just a few thoughts . . .
At 10:38 10/4/02, Ag-Schnozz wrote:
How do you define "QUALITY" in a lens?
Is it Sharpness?
Is it Contrast?
Is it Specifications?
Is it Lens Test Results?
Is it some esoteric calculations that only a geek can figure
out?
It's been a while since we've had our MC/SC/blacknose/silvernose
wars and I'm in a mood to stir the pot, I guess.
You've named only a subset of criteria to consider. I'll add a few more:
Is it Robustness (build quality, durability, etc.)?
Is it Speed?
Is it Bokeh?
Is it Flare Resistance?
Is it MTF curve, and if so, what shape curve (combo of contrast/resolution)?
Is it Flatness of Field?
Is it Absence of Barrel/Pincushion Distortion?
Is it Absence of Astigmatism?
Is it Absence of Chromatic Aberration?
Indeed, you have just done something similar to a process we use at work to
get ourselves to the important, measurable criteria. Your "QUALITY"
question goes along with the ubiquitous "What is the BEST [camera, lens,
flash, film, or fill in some other accessory here]?" questions found on
rec.photo and other fora. It is the end user who defines what "QUALITY"
means by weighting all fo these criteria (and perhaps more) with what is
more important to the end user. One man's ceiling is another man's
floor. Flatness of field may be important to someone making macros with a
lens using extension tubes, but another may not give a tinker's dam about
it because it's used for landscapes at narrow apertures.
When is a flawed lens NOT a flawed lens? Is haze on an element
necessarily a bad thing? Where does character come in?
Does it degrade any imagery it's user creates from what the "ideal lens"
would produce? If the answer is YES, then it's flawed. If the answer is
NO, then it's not. No lens is perfect compared to the theoretical ideal in
mapping reflected light from 3-D space to 2-D flat film. Admittedly, this
means *every* lens is flawed in some manner. It then becomes a decision
about whether the flaw(s) is(are) acceptable.
Science and art sometimes mix. With good science, you attempt to eliminate
all possible variables that could affect the outcome of a test. In a lens
you may seek absolute sharpness, color accuracy and flare
control. Basically, you want exactly what is there to be captured by the
film in exactly the manner that it exists in real life. Art is typically
different, though. Art is typically less concerned with scientific
accuracy as it is interested in affecting an emotion on the viewer.
I prefer to have the most exacting and accurate optics, as close to the
ideal rectilinear or spherical fisheye lens in mapping 3-D space to 2-D
flat film as possible. The "art" can then be left to the user's choice
about which deviations from the "ideal" to introduce, and their
magnitudes. Example: the user can introduce flare deliberately, but it's
hard as Hades to eliminate it.
No 2-D "still" image is capable of rendering how an object exists in real
life. The first problem is a lack of the object's environment. A
photograph is a recording of light on a two-dimensional in one space and
time that is played back for its viewers in another space and time, and it
is limited to a finite size. No matter how wide a lens is used, it crops
some of the object's environment out. The second problem is use of only
vision, a single sense. In the space and time at which the light recording
was made, all other human senses were present: taste, smell, aural, and
touch. The photograph cannot convey these directly. It can only do this
indirectly using visual cues to trigger response in the viewer's brain in a
different space and time, based on the viewer's cognizance of these cues
from prior experiences. It is possible to stimulate the other senses, if
only subtly and in memory (e.g. being able to recall smell and taste of
Alka-Seltzer by reading the posting about it). The more vivid the memory
(in the viewer), the greater magnitude of response in the other senses to
the visual stimuli.
Bottom line: a work of art relies on the experiential base of it's viewer
to convey it's message, and an artist's understanding about the
experiential base of the work's intended audience is crucial.
Example: Show an aborigine who has never seen an automobile a photograph
of just the steering wheel from a late 1960's Ford Galaxie, and he could
easily perceive it as an odd form of boomerang. Show it to someone who is
familiar with automobiles and there is a completely different perception;
it is recognized immediately as an automobile steering wheel. For me
specifically, it has additional stimuli as it is the steering wheel of the
automobile I drove on an all-night date following my high school graduation
ceremony.
Show one of your albums of wedding proofs to someone who doesn't know
anyone depicted in them and they will have a completely different response
to them than someone who was there, at that wedding, and knows the people
depicted in the photographs.
I agree completely with your statement about art's objective being
conveyance of a "message" to it's intended audience. I believe the tools
should enable widest possible latitude for the artist though.
Which brings me to my point of discussion. When is a flaw in a lens
actually a benefit?
Spoken like a salesman: "THAT's not a FLAW, that's a FEATURE!"
:-)
IMHO: only if that "flaw" is *always* desired in at least that magnitude
by its user. It's difficult for me to imagine the *always" part of this
though.
-- John
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