[LargeFormat] cult lenses

[Charles Thorsten]

Richard,

You live for this, don't you?  :-)  Glad to have you on this list
as well as pure-silver.  You're a goldmine of information.

-Charlie
 cthorsten@earthlink.net 


----- Original Message ----- 
From: "Richard Knoppow" <dickburk@ix.netcom.com>
To: "Large Format List" <largeformat@f32.net>
Sent: Monday, June 02, 2003 3:53 PM
Subject: Re: [LargeFormat] cult lenses

>   Just to clarify, Dagor is the name of a lens type made by
> Goerz. The other names are manufacturers. Each made a
> variety of lenses.
>   Goerz began as a German company. The Dagor was offered to
> them by its designer, Emile von Hoegh, after he had
> approached Zeiss and others. Goerz began manufacturing it
> and it turned out to be very successful. After WW-1 (1926)
> Goerz was forced to merge into the Zeiss-Ikon combination
> during the very severe economic depression which followed
> the war. Zeiss continued making Dagors under the Zeiss-Goerz
> name.
>   Goerz had also established US branch about 1899. This
> company became independant, probably at the outbreak of the
> war, but I don't have definite history. Goerz American
> Optical (not to be confused with the American Optical
> Company), made Dagor, Dogmar, and Aprochromatic Artar
> lenses, and some other, based on the German Goerz designs.
> Goerz lenses are noted for high quality of manufacture.
>   It is the Apochromatic Artar which was designed for
> photomechanical plate making. Some special Dagors were
> designed about the early 1950's for use in making
> photo-lithographic plates, where a wide angle lens is
> desirable. While well corrected for color these are not
> apochromatic lenses. These were sold as Trigor and Blue-Dot
> Dagor, two names for the same lens.
>   Goerz American was sold several times after the mid 1950's
> and was eventually aquired by Schneider (1971). Schneider
> continued to make the Apo Artar and contracted with Kern of
> Switzerland to make some Dagors. These seem to have been
> re-designed and were sold as Gold-Dot Dagors. These lenses
> often command high prices on the used market. The Golden
> Dagor, sometimes wrongly called a Gold Rim Dagor, was the
> same design as earlier Dagors but sold with a polished brass
> front cell. These are c.late 1950's. It was a marketing
> gimmick.
>   Wollensak was an old line US company started by the
> Wollensak brothers, two German immigrants who originally
> worked for Bausch & Lomb. The began in business for
> themselves selling shutters of superior quality. Eventually
> they entered the lens market. Wollensak shutters are
> excellent but their lenses are of variable quality. Some are
> excellent, some are dogs. They made a line of soft focus
> lenses in the 1930's and 40's (perhaps even earlier) which
> were popular.
>   Wollensak made a tremendous number of lenses under
> contract for small camera manufacturers. They had a few
> original designs but mainly made lenses of established
> types.
>   Cooke was a late entry into photographic lens making. The
> name Cooke Triplet was applied to a lens of great importance
> in lens design. It was designed by Harold Dennis Taylor, who
> worked at the time for Cooke of York, a British company who
> made mainly telescopes and optical instruments. Cooke did
> not want to make photographic lenses at the time so Taylor
> was allowed to take his design to Taylor, Taylor, and
> Hobson, a highly respected English manufacturer of lenses
> and optical instruments. The lens was named the Cooke lens
> in honor of the originating company. Later, Cooke made
> adjustable soft-focus lenses based on the Taylor Triplet
> design. This design has recently been resurrected and new
> Cooke soft focus lenses are being offered by Cooke.
>   Dallmeyer was also an English company despite the German
> name. Dallmeyer was, along with Steinheil, the inventor of
> the famous Rapid Rectilinear lens, called the Aplanat by
> Steinheil. There has always been some controversey about
> this design. Steinheil's lens was designed with the help of
> von Seidel, a pioneer researcher in optical theory.
> Dallmeyer had no such help but evidently the two designs
> were arrived at independantly and each was issued a patent.
>   Dallmeyer became well known later for introducing
> telephoto lenses.
>   While each of these companies made some excellent lenses
> and while some may be collector's items, I don't think any
> were of such outstanding quality as to command unusually
> high prices.
>  Dagors have always been popular because they are
> essentially wide angle lenses. They are quite sharp when
> stopped down but the type suffers from a large amount of
> zonal spherical aberration, resulting in some focus shift
> when stopping down. The same spherical gives the lens a
> pleasant soft focus effect when used near wide open. Modern
> Plasmat types have very much less zonal spherical. Dagors
> are expensive to make because of the four cemented surfaces
> which require a lot of extra steps in manufacture. All
> cemented lenses like the Dagor and Series VII Zeiss Protar,
> were designed long before lens coating was available to
> control flare. Reducing the number of glass-air surfaces was
> the only method open to the designer to keep flare down. Air
> spaced elements offer much more freedom of design so lenses
> with many cemented surfaces dissapeared when lens coating
> became available.
> ---
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@ix.netcom.com
> 
> 
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