Kodak Ektachrome EIR Color Infrared

Ektachrome EIR was the consumer-facing color infrared film, distinct from the aerial Aerochrome 1443 that gets most of the attention. Kodak introduced EIR (code 2236) in 1997 as an E-6-processable update to the older E-4 Infrared Ektachrome of the same 2236 designation. Where Aerochrome shipped in 35mm, 70mm, and aerial roll widths for reconnaissance work, EIR came only in 36-exposure 35mm cassettes for handheld cameras. Same false-color science, different target market.

The emulsion has three layers like any reversal film, but the red-sensitive layer is replaced by an infrared-sensitive one. Healthy chlorophyll reflects infrared strongly, so foliage that reads green to your eye renders magenta or pink on the slide while blue sky goes cyan. The effect depends on filtration: a yellow Wratten 12 gives the classic magenta foliage, while an orange or red filter pushes greens toward yellow-white at the cost of contrast. Without any filter the slide comes back muddy because too much blue light reaches the infrared layer.

Kodak rated the film at ISO 200, but expired stock is typically shot at EI 100 or 125 because the infrared layer fades faster than the other two. The whole thing depends on cold storage. Even in production years, Kodak warned the film had roughly a one-month shelf life out of the fridge before color balance began drifting.

Kodak discontinued EIR in 2007 after a ten-year run. Photographers who got serious between 2008 and the early 2010s burned through eBay freezer stock at climbing prices. Today there is essentially no usable EIR left; what you find is twenty-plus years old. Process is straight E-6.

Reciprocity exponent is 1.10. Zone Light Meter applies the correction past one second on the standard curve. A metered 30-second exposure becomes about 35 seconds at the negative. In practice you almost never expose EIR past a second; the infrared response collapses at low light levels, and the false-color effect is strongest in bright midday sun.