The E-2 process and E-3 process are outdated processes for developing Ektachrome reversal photographic film. The two processes are very similar, and differ depending on the film. Kodak sold kits that could process either kind of film.

Processing

Ektachrome film has three separate light-sensitive layers; each layer is sensitive to a different group of wavelengths corresponding to red, green, and blue colors. When the film is exposed, each layer records a latent image based on its sensitivity. A yellow filter prevents blue light from exposing the green- and red-sensitive layers, which have some sensitivity to blue light. Films are processed at 75 F with a tolerance of only ±0.5°F; exceeding these limits could cause color shifts. The steps are: The original Ektachrome process introduced in 1946 used similar steps with different durations; the total processing time was approximately 90 minutes. It was renamed to E-1 when the E-2 process was introduced in 1955 for ASA 32 Ektachrome, followed by E-3 for ASA 50 Ektachrome in 1959. Films designed for E-2 and E-3 are prone to fading because of the instability of the color dyes. The processes were phased out in 1974 in favor of E-4 (which was introduced in 1966), and two years later E-6 was introduced which remains in use to this day.