Re: Back to Basics

[captyng@vtx.ch (Gerard Captijn)]

In terms of relaxed optical design, "unverklemmtes rechnen" as per Zeiss'
Oberkochen terminology (Dr.Hohberg), one has to hope that Zeiss is not
becoming too relaxed in the calculation of their optical systems.

Before the war, Max Berek and his mathematicians did the maximum to equal
and improve on Zeiss designs but they had to use tricks to be competitive.
Not even their basic Elmar design was original: it was an improved version
of the Zeiss' Tessar (position change of the aperture). During the thirties,
the undisputed leader in lens design was Zeiss.

Today the situation has reversed. If one compares the 2.8/28mm's, the
2.0/40&50mm's and the 2.8/90mm's for Leica-M and Contax-G, performance at
medium and small apertures is approximately identical but Leica is better at
the largest apertures. During the nineties, 60 years later, the leader has
become Leica.

Maybe Zeiss should start calculating a little more "verklemmt", to increase
image quality competition with Leica, for the benefit of the photographic
community. After all, film quality is improving at a spectacular rate (200
linepairs per mm is now being recorded by increasing numbers of color
negative film) which is why we need better lenses.

Gerard Captijn,
Geneva , Switzerland.=20
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>>There are two completely different things being discussed here.  One is=
 what
>>the Carl Zeiss optical designers were striving to achieve.  The other is=
 the
>>public perception of Leica lens performance.
>>
>>The main point is that Zeiss lenses are designed for bench-test=
 performance
>>and have always tested 'well'.  Leica lenses, until the 1980's, weren't so
>>designed, and did poorly on the same sorts of tests.  Max Berek, through a
>>simple trick, caused his lens designs to produce a final image which=
 looked
>>better than it was, and this is WHY Leica lenses are renowned for an=
 optical
>>performance which cannot be found on the test charts.
>
>These are thought provoking remarks indeed. Which bench-tests are you
>referring to. There are so many. And what Zeiss lenses are you pointing at.
>Zeiss by the way is since the early seventies actively promoting this
>strategy of design relaxation, meaning that a lens design should be
>optimised for practical perposes, not bench-test results. Read the document
>by Dr Kammerer of Zeiss: "Wann sind Qualit=E4tssteigerungen bei
>photographischen Objektiven sinnvoll" (Wenn does it makes sense to improve
>on the quality of photographic optics). In this booklet the factors of
>human perception are fully accounted for.
>Would you mind elaborating on this simple trick of Berek. How can you
>design a lens to produce a final image that in the eyes of the observer
>seems to be of higher quality than it actually is. Here we' re touching on
>a very important subject, viz, the psychology of perception. There is
>clearly a difference between the functioning of  human perception and the
>cool registration of measuring instruments.
>This might explain the difference in the opinions of so many of the members
>of this LUG (who ara all keen observers of the Leica world) on the
>different aspects of Leica lenses. It seems strange that the same lens (
>for instance the Summilux 1.4/75) has been described as having a high
>contrast image at full aperture and as having a low contrast image. In such
>a divergence of opinions,  perception must play its part. But I am not sure
>which part.
>I would be interested in hearing your opinion.
>Erwin Puts
>
>
>
>
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