[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Rollei] OTish: Origins of the Sonnar
- Subject: Re: [Rollei] OTish: Origins of the Sonnar
- From: David Seifert <dseifert >
- Date: Tue, 24 Feb 2004 16:48:16 -0800
According to the gospel (_A History of the Photographic Lens_, Rudolf
"A much more profitable way to raise the aperture of the Triplet is to
insert a positive meniscus element into the front airspace. It appears
that the first to suggest this modification was a Chicago optician named
Charles C. Minor."
The commercial development of this design was the Gundlach Ultrastigmat.
The Ernostar design (predecessor of Sonnar) was developed by Bertele at
Ernemann beginning in 1919. By 1923 this design had evolved into the
famous f/2 Ernostar which was fitted to the famous Ermanox. In 1926
Ernemann was folded into Zeiss-Ikon and Bertele went to Zeiss.
Quoting Kingslake "The Ernostar lenses were continued in production under
their old names for a few years and then dropped. In 1930 Bertele began
the development of a series of excellent lenses called the Sonnars, based
generally upon the second Ernostar type (i.e. each lens had a single
positive element in front followed by a thick negative meniscus-shaped
component, with a positive element behind). In the high aperture Sonnars
the thick negative element consisted of a cemeneted triplet, with
high-index elements outside and a lower-index element between. In this
respect the Sonnars resembled the Ultrastigmat except that the narrow space
between the second and third elements was filled with low-index glass
instead of air."
As an aside Kingslake comments "It is interesting to note that the name
Sonnar had been used previously by the Contessa Company for one of their
folding cameras and for the Tessar-type lens fitted to it. After Contessa
became part of Zeiss-Ikon the name Sonnar became Zeiss's property."
Looking at the progression of designs from the basic Ernostar design
through the famous 50/1.5 Sonnar shows the absolute genius of this young
man who had done what most would be pleased to accomplish in a lifetime by
the time he was 32. The fact that he then went on to create the most
astounding set of ultawide angle designs in the Biogon shows the true
extent of his genius. Truly remarkable.
At 12:05 AM 2/25/2004 +0000, you wrote:
>This is probably one for Marc...
>As I understand it, the Sonnar design dates from
>Bertele's days at Ernemann both in basic design and
>indeed name. But my understanding has been challenged
>by someone else who states: "The original Sonnar name
>and general type goes back before Bertele. He took the
>existing four element design (the type I mentioned in
>my earlier post), filled one of the front air spaces
>with a low dispersion glass, and changed the single
>rear element into a cemented doublet or triplet.
>Certainly he turned a relatively ordinary small
>aperture design into a world beating wide aperture
>design, but the essential type, as well as the name,
>antedates his involvement". So am I wrong? Is it fair
>to say that "The Sonnar design is generally just a
>lens, typically long focus, with a negative three
>element front component (usually two or more groups)
>and a positive rear component, which nowadays is often
>a doublet, but was originally a singleton"? Or is he
>misquoting Kingslake? Or what?
>Yahoo! Messenger - Communicate instantly..."Ping"
>your friends today! Download Messenger Now