At a certain point, this all becomes nonsense. Resolution and "sharpness"
tests on most of today's lenses demonstrate a capability far beyond what can
be practically achieved by both gifted amateur and professional alike in
almost all practical circumstances.
1.) The measured resolution is only for a specific exact distance, not
the entire theoretical DOF.
2.) It can only be achieved on a bench or ungodly steady tripod with
fixed subjects and in the absence of air density variations.
3.) The film used must be able to support the resolution. I don't care
how much you may insist, no ISO 400 film will support 100 lpm.
4.) The development of the film must be first rate.
5.) At large apertures, focusing must be nearly perfect. At f/1.2, the
focusing accuracy must be to within 0.006 mm for a perfect lens to resolve
100 lpm. If the lens is capable of 100 lpm at f/1.2 (unlikely) then the
focusing accuracy must be to within 0.003 mm just to detect the capability.
If you focus at the film plane, you may achieve this accuracy if your screen
is very, very fine, you've allowed for the thickness of the protective
layer on top of the emulsion plus perhaps 1/3 of the emulsion thickness, the
contrast is excellent, the grain of the film is sufficiently fine, the
scattering in the emulsion is minimal and your focusing eye is good.
6.) Exposure must be perfect.
7.) Forget getting any range finder to track with this kind of accuracy
or any SLR to maintain this kind of mirror positioning accuracy over any
substantial length of time.
8.) All lenses (except for real dogs) are created equal (sharpness wise)
at f/8.
Conclusion: It is highly unlikely (except for real dogs) that ultra
resolution in our lenses will make our pictures any better. Contrast, low
dispersion, freedom from chromatic aberrations, resistance to flair, and
good bokeh are probably the real lens quality separators in almost all of
our applications. Even this is moot, considering that many of the great
photos of all time are not particularly sharp, have mediocre shadow or
highlight detail or none at all, composition is judged by editors and
created by cropping in the dark room, etc. Outside of studio work, the most
important factor seems to be being in the right place at the right time,
recognizing the moment for what it is, tripping the shutter at precisely the
right moment, being lucky enough to actually have film in the camera and...
serendipity.
Just my opinion.
Regards,
Bob...
Give blood. Play hockey.
From: "Rob Studdert" <[EMAIL PROTECTED]>
> On 14 Apr 2001, at 17:07, Collin Brendemuehl wrote:
>
> > Last week I looked at some shots made with Leica lenses.
> > They had the "donuts" typical of the older Nikon designs,
> > but were taken with a Leica.
> >
> > Second, it shows that Pentax, in older and newer designs,
> > lacks nothing up against the competition. It's a matter
> > of opinion on the good lenses. We've nothing to be
> > embarassed about.
>
> Hi Collin,
>
> I admit to having all but little experience shooting with the Leica R lens
range
> however as you imagine I have a fair idea of the capabilities of Pentax
glass
> across the range and also Leica M new and old. I haven't read the article
to
> which you refer but I find your distillation of it confusing given my
personal
> experience. I have found most Leica lenses (particularly the new designs)
to
> be quite sharp across the plane of focus even wide open and most also have
> very pleasing Bokeh characteristics, some of the older R glass were
actually
> Minolta designs, maybe this is where the confusion lies? I do agree though
> that the Pentax glass holds up on its own, where it doesn't win in the
> absolute sharpness stakes it usually wins WRT flare.
-
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