Kodak EIR

Kodak EIR is the 35mm color infrared reversal film that brought the Aerochrome look into a handheld camera. The catalog designation was Ektachrome Professional Infrared, code 2236, introduced in 1997 as the E-6 update to the older Infrared Ektachrome that ran on E-4 chemistry. Where Aerochrome 1443 shipped in 70mm and aerial rolls for reconnaissance, EIR came only in 36-exposure 35mm canisters for SLR cameras.

The science matches Aerochrome: a three-layer reversal film with the red-sensitive layer replaced by an infrared-sensitive one, shifted so chlorophyll foliage renders magenta or pink and clear sky goes deep cyan. A yellow Wratten 12 is required to block UV and blue that would wash through the infrared layer. An orange filter pushes foliage further toward yellow-white. Without filtration the slides come back muddy.

EIR is rated ISO 200, but the infrared layer fades faster than the green and blue layers, which is why expired stock is almost always shot at EI 100 or 125. Out of the freezer the film had roughly a month of usable shelf life before color drifted. It cost about five times a regular roll of E-6, and labs that could process it correctly were a short list even in 1999.

Compared with Aerochrome 1443, EIR runs warmer in the magentas and noticeably less sharp because of the 35mm format. Richard Mosse made his Infra series on Aerochrome cut down from 70mm rolls because EIR could not give the medium-format resolution his prints needed. For 35mm work, EIR was the only option.

Kodak discontinued EIR in 2007, citing low volume and complexity that made small runs uneconomical. What surfaces through eBay and estate sales is twenty-plus years old. Process is straight E-6. Bracket every exposure.

The reciprocity exponent is 1.10. Zone Light Meter applies the correction past one second. A metered 30-second exposure lands at about 35 seconds at the negative. In practice you almost never expose EIR past a second: the infrared response collapses at low light and the false-color effect needs bright midday sun.