[rollei_list] Contrast and Resolution and Zeiss: LONG and Primarily OT
- From: Marc James Small <marcsmall@xxxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx,rollei_list@xxxxxxxxxxxxx
- Date: Wed, 07 Nov 2007 14:18:27 -0500
Return with us to those exciting days of yesteryear ....
One of the most significant gains provided by
lens coatings was in the reduction of internal
reflections within a lens. Inernal reflections
eat up contrast more than do the effects of the
scatter on external elements. Paul Rudolph
developed the original Planar in 1896 -- a
magnificent lens and one relatively inexpensive
to develop, but it had six elements, and those
six internal lens surfaces reduced its utility by
quite a bit, so Rudolph went off and spent the
next twenty years working on the four-element
Tessar with only four internal lens surfaces made
it more satisfactory in conventional uses though
it was not as well-corrected a lens as was the
Planar. One problem with the Tessar was its poor
performance at wide apertues, and Rudolph
assigned his principal deputy, Ernst Wandersleb,
the task of allowing Tessars of up to f/2.8 to be
manufactured. After Rudolph retired -- later to
return from the dead for a stunningly successful
second career with Hugo Meyer -- Wandersleb
succeeded him as Chief of Optical Design in the
Photo Department at Carl Zeiss, Jena. Decades
later, in 1936, Wandersleb instructed HIS deputy,
Hans Sauer, to revisit the six-element Planar
with the idea of reducing the number of internal
surfaces. Sauer worked on this project for more
than a decade and produced the five-element
Planar used in our Rolleiflex TLR's though, by
the time this appeared, lens coatings had
obviated the principal reason for its development.
In the early days of lens coatings, it was not
uncommon for smaller manufacturers to coat only
the internal elements of lenses. This reflected
the greater need for lens coatings on these
surfaces than on the outside surfaces. It also
reflected the reality that Zeiss held the patent
on the vacuum-coating technology and thus most
other lens manufacturers in Germany were
restricted to a drip-coating method which left a
moist and soft film which did not work satisfactorially on external elements.
In the midst of all of this concern over internal
reflections and the impact on contrast. Zeoss
Ikon was formed in 1926. This was a sister
company to Carl Zeiss, Jena, and was controlled
by the same charitable trust, the Zeiss
Foundation. One of the assets contributed to the
new company by one of its constituents, Ernemann,
was the service of Ludwig Bertele. Bertele was
not held in high regard by the technical whizes
at Jena as he had not come up through the
customary educational and corporate routes and
did not have any formal optical training -- in
some respects, Bertele was a late bloomer in the
apprenticeship system which had produced Carl
Kellner, Carl Zeiss, and Oscar Barnack, and which
Carl Zeiss and Ernst Leitz had effectively
ended. Bertele did not want to go to Zeiss
though he was briefly sent to Jena after the
Zeiss Ikon merger. He was unhappy at Jena as he
was effectively placed in Coventry. The Zeiss
optical designers were unhappy at his presence as
they saw him as an untrained upstart. Although
Zeiss Ikon did not produce lenses, he was then
transferred to the old ICA works at Dresden and
proceeded to design lenses for Zeiss Ikon
cameras. He was told to concoct a lens line for
the new Contax RF system, and he produced, in
stunningly fast time, the 2/5cm and 1.5/5cm and
2/8.5cm and 4/13.5cm Sonnars and the 2.8/3.5cm
Biogon and, later, the 2.8/18cm and 4/30cm
Sonnars. (I believe that the 4.5/3.5cm
Orthometar, 2.8/5cm and 3.5/cm Tessars, and the
8/50cm fern-Objektiv were honest-to-Ernst Abbe
Jena products, while the Postwar 35mm Planar was
a direct design of Carl Zeiss Oberkochen.)
Zeiss Ikon had some difficulty getting Carl
Zeiss, Jena, to produce these Bertele
designs. Part of this was a basic
dog-in-the-manger NIH mentality, and part of it
was a distrust in the viability of Zeiss Ikon by
the senior Zeiss entity, and part of it was a
simple dislike of the miniature-format system by
optical engineers content to work with
large-format plate cameras and part of it was a
gut-level distaste for Bertele. The historical
record is murky, but apparently Zeiss Ikon went
so far as to contact Joseph Schneider Kreuznach,
Rodenstock, and Voigtländer about the possible
production of these Bertele designs before CZJ
relented and agreed to manufacture these
lenses. (I never interviewed Heinz Kúppenbender
or Ludwig Bertele or Hubert Nerwin, though I
certainly could have done so and should have done
so, though I have extensively interviewed those
who interviewed them, many of whom are now
sitting around a dirty table in a cheap dive in
the Optical Valhalla in the Sky, swapping tales
with Peter Barlow and the VERY grumpy Dr Petzval
-- the clean tables in the upscale bistro, of
course, are found in the Political Valhalla in
the Sky, while the Military Valhalla guys have to
swill plonk from SPAM cans while they sit around
a moldy ammo box in a dug-out command post with
the gas curtains down, the scene lit by
flickering candles shaking to incoming artillery rounds.)
It has often been noted that the terms "good
marketing" and "Zeiss" make as little sense when
used in the same sentence as do "Marc James
Small" and "U-Haul". Despite this, Zeiss Ikon
did a superlative job in marketing the new
Contax. One of the first ads touted the 2/5cm
Sonnar -- it showed Bertele and an assistant
sitting atop a stack of papers more than a meter
and a half (60 inchs) in height, representing the
paperwork used in the computation of the new
lens, some 3200 pages in all. The ad for the
1.5/5cm Sonnar was headlined, "MEHR LICHT!" --
"more light!", the last words of Goethe and
indicative of the need to hawk this system to the
emerging and educated German middle class.
Bertele went to great pains in the development of
the 1.5/5cm Sonnar as he was intensely concerned
over the number of internal surfaces necessary to
achieve that fast a lens -- it ended up with six
elements in four groups and with five internal
elements. It was a magnificent design -- late in
his life, Bertele bragged that his Postwar Biogon
designs were to photography "as the jet engine is
to aviation and penicillin to medicine" but
acknowledged that his second-happiest design was
the 1.5/5cm Sonnar, the third being the f/2
Ernostar. Diffraction effects plagued it,
though, and the lens orignally only stopped down
to f/11, a feature shown on the early coated
lenses, this lens being one of the few CZJ lenses
to be marketed with lens coatings before the
outbreak of the Second World War. Lens coatings
allowed the lens to be progressively changed to
stop down to f/16 and, finally, to f/22, a
feature which survived on the Jupiter-3 clone in
the USSR and Russia until the lens left production around 1994.
So, yes, the Prewar 1.5/5cm Sonnar was relatively
low in contrast but high in resolution, while the
addition of lens coatings improved contrast while
maintaining the high resolution. In the middle
1930's, Taylor Taylor Hobson in the UK noticed
that they were doing work on fast
miniature-format lenses which was paralleled by
work being done by Leitz and JSK, and they
suggested the pooling of resources which led to
the Leitz 1.5/5cm Xenon, also marketed as the JSK
1.5/5cm Xenon in LTM. This lens was a capable
performer but did not match the Prewar 1.5/5cm
Sonnar in performance: it was later to be reborn
as the coated 1.5/5cm Summarit and the first
version of the 1.4/50 Summilux; again, these are
estimable lenses but were still not able to match
the 1.5/5cm Sonnar. Leitz only climbed onto a
level playing field thirty years after the design
of the 1.5/5cm CZJ Sonnar when they introduced
the second version of the 1.4/50 Summilux in
1962, this redesign not being acknowledged until 1966.
I have owned a slue of all of these lenses and
still own a few of them, notably an early coated
1.6/6cm Sonnar in Contax RF BM, Jupiter-3's in
both that mount and LTM, a 1.5/5cm Summarit, and
a 1.4/50 Summilux. With a Contax, the coated
1.5/5cm Sonnar is my normal lens, with my Leica
M's, this role is taken by the 1.4/50 Summilux-M.
Heavens, but I do rattle on!
Marc
msmall@xxxxxxxxxxxx
Cha robh bàs fir gun ghràs fir!
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