[rollei_list] OT: 2/8.5cm CZJ Sonnar and its descendants
- From: Marc James Small <marcsmall@xxxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Mon, 16 Nov 2009 18:39:26 -0500
At 05:57 PM 11/16/2009, Richard Knoppow wrote:
> The fact is that the only way to test a lens is to put
>it on an optical bench and run a bunch of tests using the
>aerial image. On a camera one is testing the entire camera.
>There are all sorts of variations in lens performance; some
>have to do with the inherent characteristics of the design,
>some with the specific design, and some with the particular
>lens. There are some bad lenses; the Wollensak Tessar type
>series of the late 1940's sold as Raptar and Optar (Graflex
>house brand) were awful probably due to a design error, and
>once in a while one finds an example of poor QC or just a
>dog that escaped.
> The basic design of the Sonnar and Leitz lenses are
>quite different. The Sonnar is derived from the Triplet.
>While it is a very much better lens than a Triplet it still
>shares some inherent problems. The design was exploited
>because it has few glass-air surfaces so is low flare
>without coatings. The Leitz lenses are derived from the
>Planar/Opic/Biotar. These have a different set of inherent
>strengths and weaknesses. They have more glass-air surfaces
>so have more flare than a Sonnar. Of course, coating tames
>this. History shows that excellent lenses have been made
>using both designs. I think the Sonnar type fell out of use
>after coatings became available because it appears to be an
>expensive lens to make. The f/1.5 has four cemented surfaces
>and some pretty steeply curved surfaces, both of which tend
>to make a lens more expensive to produce.
> Do, when someone compares lenses of different designs
>on a camera I must ask what was controlled? How about focus,
>film flatness, etc. How many examples of each were tested?
> Harry Sherer seems to have a lot of Zeiss propaganda on
>his site. Some of the stuff Zeiss published is perfectly OK
>but a lot of it is self-serving. One really needs an
>independant source for education about optics.
>
>--
All extremely valid points, Richard.
The Sonnar began as a superb lens back in the
Ermanox days and has only gone from strength to
strength. Bertele was the designer best able to
tweak it to wonderful levels of performance but
he disliked working on it -- he once noted that
having produced the 1924 Ermanox lens, he found
later work boring and wanted to get on with the
Biogon designs. The Sonnar was especially
distinguished before lens coatings became
available and adapted well to them but, as you
note, it is an expensive design to produce even
today, so it gradually left the front
line. (Zeiss Ikon was planning on replacing it
on the Contax IV with the 1.5/5cm Voigtländer
Nokton, a less expensive lens to make but one
equally capable and one still markedly better than the 1.5/5cm Leitz Summarit.)
I interviewed a fellow fifteen years back who, as
a lad, accompanied his father, the partner in a
Philadelphia camera store, to New York to meet
with Dr Bauer, then the head of Carl Zeiss
USA. Bauer took them out to lunch and spoke of
the marketing plan for the new 2/8.5cm Sonnar --
it was to be sold as the sharpest possible
medium-long-focus lens, and CZUSA urged dealers
to let reporters try it out for low-light
reportage. My interviewee was then interested in
telescopes and binoculars and found the talk of
the Sonnar boring -- until his father laughed and
said, "if we sell enough of these lenses, then I
can afford to buy you that 10cm Zeiss telescope you want!"
Shucks, Richard. You get an optical lab on board
and I'll supply the lenses. I can provide a lot
of the 2/85, from an uncoated Prewar one to a
fairly late Russian KMZ version in M42.
I often do a shoot-off in the spring when I am
around bumblebees. An M6 camera, a 2/8.5 CZJ
Sonnar T (Peter Dechert's old lens) with adapter
versus the 2/90 ASPH Summicron. It is amazing
how many hairs you can count on a bumblebee's
body on pictures made from either lens.
Henry has a very select bit of Zeiss publications
on his site. He has nothing running contrary to his bogus theorizing.
No, the 2/85 Sonnar is NOT a "soft" lens nor one
intended for portraiture. Henry probably has the
Sonnar confused with the Leitz Thambar.
Marc
msmall@xxxxxxxxxxxx
Cha robh bàs fir gun ghràs fir!
---
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