Re: Back to Basics

[imxputs@knoware.nl (Erwin Puts/imX)]

>There are two completely different things being discussed here.  One is wha=
t
>the Carl Zeiss optical designers were striving to achieve.  The other is th=
e
>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 optica=
l
>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