Konica Infrared 750

Konica Infrared 750 is the calmest infrared film a major manufacturer ever produced. Peak sensitivity sits at 750nm, with a secondary visible-light response between 400 and 500nm and an IR hump out to about 820nm. The base ISO is 32 without filtration, which is unusual for an infrared stock because most IR films punish you the moment you stop blocking visible light. Without a filter, Konica IR 750 behaves close to a slow panchromatic emulsion. Drop a red 25 in front of the lens and the effective exposure index falls to around EI 25 with classic Wood effect on foliage. An R72 deep infrared filter pushes it to roughly EI 6 to 10 in practice.

The Wood effect is more restrained than Kodak HIE produced. HIE was sensitive past 900nm and rendered foliage chalk-white with a glow nothing else has matched. Konica IR 750 cuts off around 820nm, so the white leaves come back convincing but not luminous. The trade is grain. Konica IR 750 is the finest-grained traditional infrared film ever sold to consumers, noticeably tighter than Rollei IR 400, Efke IR 820, and HIE itself. For architectural infrared work where you want the look without the texture, this is the stock photographers chased.

Unlike Kodak HIE, the film loads in daylight. No felt-lined cassette dance, no changing bag. Develop in HC-110 dilution B, Rodinal 1:50, or XTOL 1:1. Pyrocat-HD around 8 and a half minutes in BTZS tubes prints clean.

Konica discontinued the film around 2005. It was sold in 35mm and 120 only, never in sheet. Supply now is expired freezer-stock and warm-stored estate finds. Rolls fifteen years past their date code still turn up usable because IR sensitivity holds up well in cold storage. Base fog rises over time and is the real limiting factor.

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. IR work almost always means tripod and bright sun, so the threshold comes up less than you might expect. When it does, the math matters.