Werner Bischof – Unseen Colour
Devin Tri-Color camera
The Devin Tri-Color camera was one of the first photographic devices to use the trichromy process. Although there are earlier examples of the use of this technique, as an initial scientific demonstration occurred back in 1861, the breakthrough did not come until 1938, with the one-shot model from the Devin Colorgraph Company in America.
The Devin exposes three black-and-white glass negatives simultaneously via two partial mirrors. A colour filter is placed in front of each glass plate so that one negative captures only the red hues, one only the green hues and one only the blue hues. With these different colour separations, printing plates can be prepared for the colours cyan, magenta and yellow. When these are printed on top of each other in the production of a magazine or book, the result is a colour representation that corresponds to human perception. Today, the three negatives can be scanned, coloured and digitally combined as a single colour image.
The apparatus exhibited here is the original Devin Tri-Color camera, very expensive at the time, which the Zurich publishing house Conzett & Huber, publisher of the magazine Du, purchased specially for Werner Bischof – and made available to him for advertising shots, cover pictures and reportage.
Where do the colored edges come from?
In Werner Bischof’s day, black-and-white negatives made with the Devin Tri-Color camera were not transferred into color images until they were printed in a magazine or book. Today, thanks to digitization, it is possible to produce high-quality exhibition prints: The three black-and-white glass negatives are digitized individually. Next, the three so-called color separations are assigned in an image processing program to the RGB channels on which the color mixing on the screen is based: The superimposition of red, green and blue enables the display of finely graded color tones (additive color mixing). These RGB images are finally prepared for printing in cyan, magenta and yellow (subtractive color mixing).
On the prints of the Devin images in our exhibition, this process remains visible: The edges of the negatives, which are not perfectly congruent when superimposed, were deliberately left as colored frames. They remind us that the coloration was “reconstructed” in several steps.
The digital reconstruction of the color scheme was based on the historical references, i.e. on the images actually printed during Bischof’s lifetime. In many cases, however, no references exist, so that the color nuances had to be determined subsequently. The scan as well as the image preparation for inkjet printing on paper were precisely coordinated – a process that is not free of subjective decisions.
Rolleiflex Automat
Werner Bischof had been familiar with the Rolleiflex since childhood, as his father had already taken photographs with it as an amateur. It is a medium-format reflex camera of excellent optical and mechanical quality. It has two lenses: an upper one for framing the picture and a lower one for taking the photograph. The photographer holds the camera at stomach level and sees the image from above, inverted on a ground-glass screen, which affects the shooting angle, framing and composition. One special feature of Rolleiflex photographs is the square format (6 x 6 cm). This was also popular with many photojournalists because it could be used to create both landscape- and portrait-format images, for incorporation into an appropriate layout. Werner Bischof appreciated the precision and reliability of the Rolleiflex; he used it throughout his career and became a master of composition in the square format.
In 1947, Kodak introduced the slide film Ektachrome. Available as a roll film, it was coated with an emulsion in which the components for producing yellow, purple and magenta dyes were embedded. Thus, to produce a colour slide, all that was needed was a single image, which was then broken down into colour separations for printing. Bischof already started working with Ektachrome in 1947, although this first colour film for medium-format cameras still had colour-stability issues at that stage.
Leica
In the 1950s, Werner Bischof mainly photographed with the Leica. This brilliant invention from Oscar Barnack, technician and designer at the firm Leitz in Wetzlar, is a small lightweight camera for 35 mm film, with interchangeable lenses; it went into mass production in 1924 and was immediately a huge success. The image resolution is not quite as high as that of the Rolleiflex, but with its handiness and quick operability, it revolutionised photojournalism. It was no matter of chance that the Leica became the preferred camera of photographers working with the legendary cooperative Magnum Photos.
The first 35 mm colour slide films suitable for the Leica were brought onto the market by Kodak in 1936 under the name Kodachrome, but it was not until 2 years later that such films could produce colour-stable slides. Like Ektachrome, they were based on a ‘chromogenic’ process with three superimposed layers, each sensitised to blue, green or red. Kodachrome slides were sharp, fine-grained, vividly colourful and also highly archivable. As early as 1938, the leading American magazine Life began to ask selected photojournalists to take pictures with Kodachrome: Alongside Robert Capa, for example, these also included Switzerland’s Walter Bosshard, whose first colour pictures from the Sino-Japanese War appeared in Life on the 8th of August 1938.