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[Rollei] Re: OTish: Origins of the Sonnar

I'd just add that these original Sonnars were not long focus...

Eric Goldstein

> Nick,
> According to the gospel (_A History of the Photographic Lens_, Rudolf
> Kingslake, 1989)
> "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.
> David
>> 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?
>> Nick