Kodak Aerographic 2424 IR

2424 is the infrared cousin in the Aerographic line, engineered for vegetation surveys, water mapping, and haze cutting from aircraft. The emulsion is sensitive into the near-infrared (Kodak rated spectral response out to about 900nm in the AS-58 datasheet), with strong UV and visible response as well. Used unfiltered it behaves like a slightly weird panchromatic film. The point shows up only with a deep red or infrared filter on the lens.

With a Wratten 25 red, Kodak's guidance is that 2424 needs about one stop more exposure than 2402 unfiltered. Aerial speed is ISO-A 400 unfiltered; with a Wratten 25 most ground users settle around EI 200 to 320, and a Wratten 87 drops that to roughly EI 25 to 50. The Wood effect kicks in hard: healthy chlorophyll-bearing foliage reflects strongly in the near-IR and prints near white, clear sky goes inky, water turns black. Richard Mosse used Aerochrome for the same physics on color. 2424 gives you the monochrome version.

The common path for ground users was respooling 70mm bulk down to 120, which several specialty cutters did through the 2000s. That supply has dried up. Kodak imposed an 18-roll minimum on 70mm 2424 orders and set a final order deadline of August 31, 2005, which effectively pulled it from most catalogs. Compared to retail Kodak HIE (35mm high-speed IR discontinued in 2007), 2424 is finer-grained and less wildly IR-sensitive, which makes it easier to predict. HIE could be focused only by trial. 2424 works at the IR focus index on most lenses.

Process in D-19 or DK-50 for high contrast, or HC-110 dilution B for a more pictorial scale. Load and unload in total darkness; the film fogs through any leak.

Formats were 5-inch, 9.5-inch, and 70mm rolls. The 120 respool was a community workaround. Freezer stock only.

Reciprocity exponent is 1.31. Zone Light Meter applies the correction past one second. A metered 30-second exposure becomes about 90 seconds at the negative. Through an opaque IR filter in bright sun you can still land at one or two seconds at f/16, right at the threshold.