Kodachrome Characteristics

Emulsion

Kodachrome is fundamentally different from other transparent and negative color films with dye couplers incorporated into the emulsion layers. Kodachrome is unique because it has no dye couplers in the emulsion; these are introduced during processing. Without couplers, the emulsion layers are thinner, causing less light scattering and allowing the film to record a sharper image. A Kodachrome slide is discernible by an easily-visible relief image on the emulsion side of the film. Kodachrome has a dynamic range of around eight stops, or 3.6-3.8D.

Kodachrome was invented in the early 1930s by two professional musicians, Leopold Godowsky, Jr. and Leopold Mannes, hence the comment that God and Man-made Kodachrome. It was first sold in 1935 as a 16mm movie film, and in 1936 it was made available in 8mm movie film and slide film in both 35mm and 828 formats. Kodachrome would eventually be produced in various film formats, including 120 and 4x5, and ISO/ASA values ranging from 8 to 200.

Digital scanning and resolution 

A 35mm Kodachrome transparency, like other 35mm transparencies on films of comparable ISO rating, contains an equivalent of approximately 20 megapixels of data in the 24 mm x 36 mm image. Scanning Kodachrome transparencies can be problematic because the film tends to scan with a blue color cast. Some software producers deliver unique Kodachrome color profiles with their software to avoid this. However, a calibration with a particular Kodachrome target is necessary for accurate color reproduction.

Typically, dust, scratches, and fingerprints on the slide are detected and removed by a scanner's software. Many scanners use an additional infrared channel to detect defects, as the long wave infrared radiation passes through the film but not through dust particles. Kodachrome interacts with this infrared channel in two ways. The absorption of the cyan dye extends into the near IR region, and thus this layer is opaque to IR. Kodachrome also has a pronounced relief image that can affect the IR channel. These effects can sometimes cause a slight loss of sharpness in the scanned image when Digital ICE or a similar infrared channel dust removal function is used. 

Processing of Kodachrome films

Kodachrome processing has undergone four significant alterations since its inception. The current process is designated Process K-14. The process is complex and exacting, requiring technicians with extensive chemistry training and large, difficult-to-operate machinery. This effectively precludes amateurs or small laboratories from processing Kodachrome. 

First, the antihalation backing is removed with an alkaline solution and washed. The film is developed using a developer containing phenidone and hydroquinone, which forms three superimposed negative images, one for each primary color. 

After washing out the first developer, the film undergoes three re-exposure and re-development stages. Re-exposure exposes the silver halides not developed by the first developer, effectively fogging them. Filters exist between each layer to prevent light from exposing the incorrect layer. A color developer then creates the fogged image, and exhaustion products form a color dye in the color that is complementary to the layer's sensitivity. For example, the red-sensitive layer forms a cyan dye. 

The metallic silver is converted back to silver halide salts following color development using a bleach solution. The film is then fixed, making these silver halides soluble and leaving only the final dye image. The film is finally washed to remove chemicals that may cause deterioration of the dye image, dried, and cut. 

Legality of paid processing

Due to the complexity of its processing, Kodachrome was initially sold at a price that included processing by Kodak. They had an envelope with the film, in which the photographer would send the exposed film to the nearest of several designated Kodak laboratories. The film was processed, mounted in 2" x 2" cardboard mounts in the case of 35 mm slides and returned by mail to the sender.

After 1954, as a result of the case United States v. Eastman Kodak Co., this practice was prohibited in the United States as anti-competitive. Kodak entered a consent decree, ending this product tying practice in the United States, and allowed independent processing laboratories to acquire the chemicals needed to process Kodachrome films. 

Decline

The use of slide film, in general, declined in the 1980s and 1990s, which, combined with competition from Fuji's Velvia slide film, caused a drop in Kodachrome sales. Kodak gradually discontinued Kodachrome products, and on 22 June 2009, Kodak announced Kodachrome would no longer be manufactured. 

Many Kodachrome processing laboratories, both Kodak-owned and independent, closed because of the decreasing volume of business. The loss of processing availability further accelerated the fall in Kodachrome sales. On 25 July 2006, extensive documentation about Kodak's Lausanne Kodachrome lab's impending closure was sent to the European Parliament by the Dutch office of the European Parliament because, although located in Switzerland, the facility served all of Europe, and its closure would affect European photographers. The Parliamentary committees for Culture and Education and Internal Market and Consumer Protection studied the matter. Kodak no longer processes Kodachrome film and instead subcontracts the processing work to Dwayne's Photo, an independent facility in Kansas, which as of 2009, is the only remaining Kodachrome processing facility. Kodak fully endorses Dwayne's processing of 35 mm films, but Dwayne's Super-8 process is not supported because it requires more agitation. Films sent for processing in the U.S. are mailed directly to Dwayne's, while those sent for processing in Europe are sent to the Lausanne facility's address. Hence they are forwarded to Dwayne's.

Kodak had previously attempted to increase the availability of K-14 processing through the K-Lab program, where small labs equipped with smaller Kodak processing machines would supplement Kodak's processing services. These labs have all closed. 

Recently-discontinued Kodachrome products

• Kodachrome 64 film in 120 formats stopped in 1996.

• Kodak discontinued Kodachrome 25 in 2002. Many point to the introduction of Velvia or the decline in processing quality as the reason for its demise.
• Kodachrome 200 was discontinued in November 2006. The last emulsion batch was numbered 2672, labeled with an expiration date of September 2008.
• Kodachrome 64 and Kodachrome 64 Professional 135 format were discontinued in June 2009.

Product timeline

K-11 process

K-12 process

K-14 process