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Duo Six-20

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The Duo Six-20 is a 4.5×6 horizontal folder made by Kodak AG from 1934 to 1940. As the name implies, it used 620 roll film.

The original model has a folding optical finder (though some f/4.5 models had a simple frame finder without optics) and a key for film advance on the left of the top plate. The earliest of the Duo 620s with painted top plate did not have the single sliding metal plate in the back that cover both of the two film counter windows, but have individual brass covers that rotate on rivets, and it seems that the very earliest have no covers at all.

Examples of the original model have been seen with both f/3.5 and f4.5 Kodak lenses. One early f/4.5 model has been seen with a dial set Pronto shutter instead of the more common rim set Compur shutter. One f/4.5 model, likely very early, has been seen with Compur shutter and no covers at all for the ruby windows in the back. The back looked totally original with no evidence of modification, with the Duo 620 logo embossed vertically to the left of the windows. The other of these had the above mentioned individual counter window covers and the Duo 620 logo horizontal. One early model has been seen with just one rotating brass cover of the correct type, but it possibly had been installed at a later date.

On the right side of the top plate is a depth of field calculator dial. Informally referred to as the "art deco" model, the top plate is painted black with typical Kodak style 'deco' raised metal geometric highlights, also seen on Model C Kodak folders of the era from the Nagel factory, and possibly others. Metal parts are nickel plated. The leather backs of the earliest models are embossed with Duo 620, printed all in one line, while later models are embossed Six-20 Duo, with Six-20 printed above Duo. Produced from 1934 to 1937, it originally sold for $57.50[1] (app. $900 USD in 2007).

The Duo Six-20 Series II, has modified folding struts, a chromed top plate and metal parts, an advance knob replacing the original key, and an accessory shoe, including European models. The shutter release was moved from the lens mount (where the cable release socket remained) to the top plate.

The depth of field calculator wheels of Kodak Series II cameras in the collection of flickr's Ektarama, host of the Kodak Duo 620 group, are as follows:

Kodak f/3.5 in English, Zeiss Tessar f/3.5 in German, Zeiss Tessar f3.5 in French!!, and Schneider Xenar f3.5 in German.

The Series II cameras have been found with the leather backs embossed with the Duo 620 inscription printed all in the same line (1. early 1937 example with f/4.5 Kodak lens, 2. unknown date with f/3.5 Zeiss Tessar lens and French DoF Calculator, 3. unknown date with f/3.5 Xenar lens), Kodak Duo 620 with inscription written in the same line (unknown date with f/3.5 Zeiss Tessar lens and German DoF calculator), Six-20 Duo Ser. II with inscription printed on 2 separate lines (unknown date with f/3.5 Kodak lens), and as Kodak Duo Six-20 Series II with inscription printed on 3 separate lines (unknown date but very late, with f/3.5 Kodak lens).

Produced from 1937 to 1939, the Series II model also originally sold for $57.50 USD[1].

The non-rangefinder Duo-620 was available in two shutters, the Compur and the Compur Rapid. A number of different lenses were offered:

European models

  • Zeiss Jena Tessar f/3.5 7.5cm
  • Schneider Xenar f/3.5 7.5cm
  • Schneider Xenar f/4.5 7.5cm.

U.S.models

  • Kodak Anastigmat f/3.5 7.5cm
  • Kodak Anastigmat f/4.5 7.5cm

The f/4.5 lenses utilized front element focusing, while the f/3.5 lenses were unit-focusing.

There is some confusion over the origins of the Kodak Anastigmat lenses on cameras on cameras imported to the United States. There are numerous claims that the lenses are simply re-branded Xenars, while Kodak (in 1938) clearly described the f/3.5 lens as a triplet[2]. To further complicate the issue, the f/4.5 model pictured here has a triplet lens, while the f/3.5 model pictured has a 4 element lens like the Xenar.


Duo Series II with Rangefinder

The last model of the Kodak Duo is the rare rangefinder model with a combined range- and view-finder inside the top housing. With this model the single film counter window was moved to the top left of the back, replacing the two window system of the earlier model that was located at the bottom right of the back. The button that opens the camera front door was moved to the bottom plate of the camera from it's previous location on the camera top. Cast metal strap lugs were placed at the sides of the top housing.

Perhaps the most significant design innovation of the new model was the introduction of automatic indexing film winding, eliminating the need to look at the ruby window after every shot. After frame number 1 was advanced to show in the window, all frames after that would advance to the next frame by turning the winding knob until it stopped. This may have been a first for folding medium format cameras. The Duo's index film advance system is very similar to the indexing system used in the Monitor Six-20. One can speculate whether the design was accomplished in Germany or the U.S., but the earliest Monitors seem to date from 1940, indicating that perhaps the design came from the Nagel engineers.

The new model was introduced in the same month that Germany invaded Poland (September of 1939), which was very unfortunate timing. Few of these cameras were made, as all camera production was halted by Kodak AG for war materials production (including aviation bomb sights) in mid 1940. Examples of the rangefinder Duo Six-20 in the collection of Flickr's Ektarama have backs embossed Kodak Duo 620, printed all on one line (S/N 334140K Xenar f/3.5), Kodak Duo Six-20 Series II, printed on two lines (S/N 332904K Kodak f/3.5), and Kodak Duo Six-20 Series II, printed on two lines with Made in Germany at the very bottom center of the back (S/N 335183K Xenar f/3.5). The serial numbers of these 3 examples span 2279 numbers. If the numbering system was in linear progression, we can be sure that at least 2279 examples of the last Duo model were produced. Sadly, when camera production resumed at Kodak AG Nagelwerk after the war, the Duo Six-20 Series II rangefinder model was discontinued.

The Duo 620 originally sold for $84.50. [1]( app. $1300 USD in 2007).

The rare RF model was sold both in the U.S. and Europe, with a Compur Rapid shutter and a Kodak Anastigmat f/3.5 7.5cm in the U.S., and Xenar 3.5 in Europe.

There are Japanese copies of the Duo, including the Semi Prux copying the original model, and the Roavic, Apollo and Mikado, copying the body of the Series II with the addition of a top housing.

ReferencesEdit

  1. 1.0 1.1 1.2 History of Kodak Cameras at www.kodak.com
  2. Kodak Lenses and Shutters

Bibliography Edit

Links Edit

In English:

In French:

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