Technical Notes
Diapositives (Color Slides)
For many years, the color slide film used by most professional photographers who used 35 mm cameras in remote places was Kodachrome. It had the finest grain of all slide film, but it was slow. Until 1987, the fastest Kodachrome had an ISO of 64. It tended to be more garish than some other slide films; its colors could be a little too vivid. It was overly sensitive to reds, which tended to be monotone, and its greens could be muddy. Highlights sometimes turned pink. Skies were usually too magenta, giving them a gray-blue or navy appearance as opposed to a more turquoise or robin's egg blue.
Kodachrome was used by most National Geographic photographers until at least 1980 or later, and the excessive contrast, blocked shadows, and the blue-jean blue of the skies were magnified by the fact that Cibachrome prints were used for the lay-out from which separations for the plates were made. Partially for these technical reasons, the magazine bred a style which favored high contrast and bold color. Something bright red in the picture was almost obligatory. Also, the vertical format of National Geographic works against landscape. Despite the title of the publication, one is much more likely to see in its pages pictures of brightly colored dancers at a festival than the subtle colors of a landscape. Portraits outnumber landscapes on its pages, and what landscapes do appear are likely to be night shots or other special-effect images in which the high-contrast can be used to good effect.
Kodachrome slides keep better than Ektachrome slides in dark storage, but they fade more rapidly when projected. On several occasions I worked in the field for months using Ektachrome and Kodachrome only to find that all of the Kodachromes were useless while all of the Ektachromes were fine. After the early years I rarely used Kodachrome at all. It has been several years since I heard a photographer mention Kodachrome, and it may no longer be made. I would suggest that if Kodalchrome film is to be used it should not be purchased abroad, and one should first test a roll and use only rolls with the same emulsion number as the tested roll.
During the early 1970's the fastest color slide film available was GAF 500. It had an ISO of 500 at a time when Kodak's fastest slide film, High Speed Ektachrome, had a speed of 180. This film went out of production late in that same decade, but there are five images in the folio which were made with GAF film; A1, A2, A4, A23,l and A24. Its speed was very useful and its colors, though very inconsistent and often streaked, were interesting. It had visible grain, huge grain, which give some images a pointillist effect.
Ektachrome films of the 1970's and 80's had their problems, as do all films; they were not quite as sharp or as fine grained as Kodachrome, and they tended to have an overall blue cast. However, they had less contrast than Kodachromes, and I found them to be more dependable. If slides are frozen while not in use, storage life ceases to be a factor, and Ektachromes have better light stability then Kodachromes. Skies are a softer blue. For several projects shot in the early 1980l's (Ceylon and Ladakh) I used primarily Ektachrome 200. Small sacrifices in grain, sharpness, and color saturation were an acceptable price to pay for the depth of field and soft colors of Ektachrome 200.
When I returned to the field in 1995 for the first time in over a decade, I took Fuji Provia. A friend of mine had been asked to test Kodak Lumiere and Fuji Provia, and in blind tests he had a difficult time telling them apart. He did say, however, that the Fuji film did better when it was pushed. Lumiere looked a bit more harsh after being pushed. To "push" a film means setting the camera for a faster speed (underexposing the film) then increasing the processing times. I shotl for two months in India and was very pleased with my film choice.
Films change and new products enter the market every year. I have used Agfa films, and would like to try them again also. Agfa film does very well when browns and grays are important colors. These are only my own observations and conclusions, and they are based on a limited range of problems. It is generally more satisfactory to use only one or two types of film on a set of pictures which are to be shown together. No film is perfect, but we tend to accept and adjust rapidly to color shifts that are uniform. When pictures from different kinds of film are hung together the color shifts in each become more noticeable. By printing with dye transfer these can be more easily balanced so that they will go together.