Kodak HIE

Kodak HIE had no anti-halation backing. Most films coat a dark layer behind the emulsion to absorb light that passes through without being captured, preventing it from bouncing off the film base and re-exposing the emulsion from below. HIE skipped that layer entirely, which produced the characteristic soft glow around bright specular areas: bare lightbulbs, sunlit windows, anything with a strong point source. That glow is the signature. You either want it or you don't.

The infrared sensitivity peaked around 750 to 900nm depending on the lot. Shot with a Hoya R72 filter, which blocks visible light below 720nm, foliage went white because chlorophyll reflects strongly in the near-infrared. Skies went black because atmospheric scatter drops off dramatically at those wavelengths. Skin went pale and slightly waxy, with darkened lips. The bleached foliage and dark water that infrared shooters chase show up in other processes too: Sally Mann's Deep South work from the late 1990s gets a similar otherworldly look from wet-plate collodion rather than from IR film. The HIE signature is closer to that mood than to any conventional panchromatic stock.

Loading required genuine darkness. The film was sensitive enough to infrared radiation that a changing bag under a red safelight was insufficient; you needed a truly dark room. Carry a film changing bag and use it inside a closet. Focus required manual correction because infrared wavelengths focus at a slightly different plane than visible light. Most Nikon and Canon manual-focus lenses had a red dot on the focus ring as an infrared focus compensation mark.

Kodak discontinued HIE in 2007. Rollei Infrared 400 and Ilford SFX 200 partially fill the gap but neither has the extended sensitivity or the anti-halation-free glow. Efke IR820 and Maco Cube IR 820c ran similar chemistry for some years after.

Reciprocity exponent is 1.31. Long exposures compound with the filter factor from the R72, so the actual shutter time compounds quickly. Zone Light Meter applies the reciprocity correction past one second; you account for the filter factor separately in the ISO or exposure compensation field.