DX encoding

In order to simplify the handling of 35 mm film in 135 format cartridges, Kodak introduced the DX encoding method on 3 January 1983.

[1][2] In contrast to the film speed encoding method developed by Fuji in 1977,[3] which used electrical contacts for film speed detection on 135 format cartridges,[4] Kodak's DX encoding system immediately met success in the marketplace.

The first point-and-shoot cameras to use DX encoding to automatically set film speed were released in 1984, including the Pentax Super Sport 35 / PC 35AF-M[5] and Minolta AF-E / Freedom II.

[6] The first single-lens reflex cameras to take advantage of DX encoding were released in 1985, including the Konica TC-X SLR (1985),[7] Pentax A3 / A3000,[8] Minolta 7000[9] (February 1985) and 9000 (September 1985), and the Nikon F-301 / N2000.

Interpreting the DX film edge barcode may provide this information, permitting accurate color correction to be applied.

The left-most area of both rows (with the spool post on the left) are common (ground) and are thus always bare metal.

Diagramatically (with spool post to the left): In this scheme: Most cameras read the film speed only, which is in the first row.

Some cameras aimed at the consumer market only read enough bits in the first row to distinguish the most common film speeds.