Kodak Plus-X Pan Professional 125

Plus-X is the slow half of the Magnum-era working pair. Tri-X went in one camera body for action, Plus-X in the other for tonality and resolution. Kodak introduced Plus-X as a motion picture stock in 1938 and rolled out a still version not long after, but the ISO 125 emulsion most photographers remember dates from 1954. The 120 roll carried the PXP code; sheet film ran as PXT; the 35mm cassette stayed PX until a late reformulation around 2003 renamed it 125PX. Production ended in 2009 and the last batch shipped through 2011.

The grain is cubic and fine. Not as fine as Panatomic-X at ISO 32, but finer than Tri-X by a clear margin and structured so it prints with smooth gradation rather than the salt-and-pepper texture of the faster stock. In D-76 at 1:1 the negative comes back with a long curve and shadow detail that holds well below middle grey. HC-110 dilution B punches up acutance at the cost of slight grain increase. Working labs leaned on D-76 for the predictable mid-tone scale.

Against Ilford FP4+ at the same ISO, Plus-X had a slightly straighter response curve and more aggressive highlight rolloff. FP4+ keeps highlight texture longer; Plus-X has a touch more snap. Studio portrait photographers in the seventies and eighties picked it for the way skin moved into the upper midtones with subtle compression.

Box speed is 125. Most photographers shot it there. A handful of magazine printers rated it at 100 for thicker negatives. Past 1990 the PXP medium format pack was the format you saw on professional shoots; the 35mm cassette circulated as the workshop and student film.

The reciprocity exponent is 1.26. Zone Light Meter applies the correction past one second. A metered 30-second exposure lands at roughly 75 seconds at the negative. Anyone who shot Plus-X for architectural interior work past the late afternoon knew the math. Freezer rolls turn up through estate sales and tend to fog mildly, but 20-year-old stock at EI 80 still produces usable negatives.