Lenses, Contrast and More (long)

[P3D Eric Goldstein <egoldste@xxxxxx>]

P3D Sam Smith wrote:

> Can a
> lens actually increase the contrast of a scene, or is this just in
> relationship to other lenses?

As George G pointed out, lenses at best can preserve the contrast of a
scene, and at worst can diminish or flatten contrast to unattractive
proportions through both flare and poor design (lack of accutance or
edge contrast). Under most circumstances, we perceive the world with far
greater contrast than photographic materials can capture, so no contrast
enhancement is needed!

With regard to dirty/foggy lenses and filters, it is easy to confuse
loss of resolution with loss of contrast, though they certainly can go
hand in hand.


George T writes about realist 3.5s versus 2.8s versus belplascas...

Of the many interesting aspects George raises, I think the most relevent
is his point regarding the _significant_ individual variation one finds
with 50's cameras. Although 4 element in 3 group tessar lenses will _in
general_ give better corner resolution than triplets (at f/11 as well as
wide open, apples-to-apples), one can find a well-matched, well-tweeked
3.5 triplet camera which will be superior in performance to individual
examples of poor 2.8 cameras.

So while as an aggregate, 2.8 realists will be better in the corners
than 3.5 realists, the particular camera you are thinking of buying my
or may not have sharp, well-matched lenses. Or if it does, it may not
appear to be sharp because it is not well adjusted.

So, is it worth spending an extra $250 for the particular 2.8 you are
drooling over?

A couple of things to consider... firstly, is superior corner sharpness
always desireable? I would say not. I can think of many photographic
situations (such as portraiture) where the characteristics of center
sharpness with some fall-off in the corners (as with triplets) is
desireable. Some expensive modern lenses are designed with this
characteristic! The cooke triplets in the 3.5 realists are about as
sharp in the center as the 2.8s, which is why most people say there is
no apparent difference. Also, some triplets such as the Ilexes Paragons
and the Rodenstock Trinars, seem to have better coatings and better
contrast than some of the David White 2.8s, and better contrast can give
the appearance of superior sharpness.

Second, how much improvement can an experienced technician tweek into
most 50's cameras? A great deal. It is very common for infinity focus to
be off in these cameras, or for focus not to be matched between lenses,
or for the rangefinder to be out of calibration. Jess Powell or Ron
Zackowski can add a lot of "sharpness" to most of these cameras with a
thorough c/l/a.

Third, hand-holding your camera diminished sharply noticably, even at
the top shutter speeds. Ansel Adams notes that he could see clear
differences in sharpness in his hand-held normal lens 35mm shots at
speeds up to 1/250th!

Personally, I think that folks starting out might want to consider
buying a decent 100 buck 3.5 realist (such as one from that box of
"junkers" George will be getting), send it off to Jess Powell to get it
tweeked to the max, buy a good tripod or monopod, and spend the rest on
a Themalized Red Button viewer. For your $350 investment, you will have
all the tools needed to deliver total system performance which will
really impress you!

If you're further along and more "into it," perhaps a 2.8 Realist
"Germany," Ektar, German, rare-earth Custom hybrid, or Belplasca is
worth considering. Good examples of each of these cameras can yield
superior optical performance, and different "looks" in the chromes (some
warmer, such as the Ektars and Belplascas, some cooler such as the
Germans, "Germany"s and rare-earths) which different photographers find
more and less appealing.

But I would not buy any example of any of these cameras without
carefully testing it first! They are all subject to the individual
variations which George spoke of in his recent post.


Eric G.


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