Film Speed

as green, and blue reproduces as black (because the film is exposed through a deep yellow filter). Many other colors are also formed, depending on the proportions of green, red, and infrared reflected from the original scene. Infrared color film was designed for camouflage detection, and it shows differences in infrared reflectance between live, healthy vegetation and areas visually similar, such as pseudo foliage and camouflage netting. Color IR film should be exposed through a minus blue (deep yellow) filter, such as a Kodak Wratten No. 12 or equivalent. CAUTION Kodak Ektachrome Infrared film can not be processed in Process E-6. It must be processed in Process ME-4, Process EA-5, or Process E-4. Do not attempt to process Kodak Ektachrome Infrared film through any type of E-6 processor. This could impair the processor and ruin the chemicals. FILM SPEED A speed-rating method for aerial film is known as Aerial Film Speed (AFS). This speed-rating system is adopted by the American National Standards Institute (ANSI) and is used to establish the speed of aerial film. Effective Aerial Film Speed (EAFS) is used to describe the actual aerial film speed that results from processing film through any process other than the one specified by ANSI. Aerial Film Speed and Effective Aerial Film Speed should not be confused with ISO speed or exposure index (EI). They are NOT equivalent. When using ground pictorial films that are assigned an ISO speed, such as Vericolor, Ektachrome, or Technical Pan, you should conduct tests to determine which film speed settings for your camera or light meter will produce optimum results. 4-16 Figure 4-15.—Aerial photograph taken with black-and-white IR film and a filter.