E 3 process

The E-3 process is a now outdated process for developing color reversal (transparency) photographic film, which was invented in the early 1950s.

The E-3 process was run at near room temperature (24°C/75°F) and requires a manual reexposure of the film in order to affect color development. Often, still photographers would accomplish this by use of a strobe unit in the darkroom. The process took approximately one hour.

Films designed for E-3 are prone to fading because of inferior color dyes. The process was phased out in 1974 in favor of E-4, and two years later E-6 was introduced which remains in use to this day.