Kodak · ISO 400 B&W negative
Kodak Tri-X 400
Tri-X is older than most people who shoot it. Kodak introduced the modern emulsion in 1954 and reformulated it once in 2007. Basically nothing else has changed since the Kennedy administration. Every Magnum photo book you have ever opened has Tri-X in it. Robert Frank shot The Americans on it. Sebastiao Salgado shot every long-term project from Workers to Genesis on Tri-X, often pushed to 1600 or 3200 in low light.
The grain is the famous thing. It is structured, salt-and-pepper, the way an editorial photo "should" look. T-grain stocks like T-MAX 400 give you cleaner negatives but they do not give you that texture. Push Tri-X to 1600 in a bar at night and you get the stairwell look that defined a generation of street work. Pull it to 200 and you get cleaner mid-tones with surprisingly graceful highlights.
Reciprocity is mild for a traditional silver-grain stock. The exponent is 1.31, so a 30-second meter reading climbs to about a minute and a half on the negative; a fifteen-minute moonscape becomes closer to an hour. Zone Light Meter does the math the instant you cross one second.
The honest weakness: highlight texture in bright scenes. Tri-X compresses skies. If you are shooting beach scenes at noon, T-MAX 100 or Delta 100 will give you cleaner zone IX rendering. For everything else, this is still the answer.
How the app handles this stock
- Box speed: ISO 400. Picker exposes pull/push chips so you can shoot it at any speed you want and the meter follows.
- Reciprocity: Above one second the app raises metered time to the power of 1.31.
- Expired film: if you load an old roll, set the expiry year and storage in the app and the ISO scales for you. B&W negative decay rates are baked in.