Kodak · ISO 8 B&W negative
Kodak Kodalith Ortho 2556
Kodalith Ortho 2556 Type 3 is the high-contrast graphic-arts sheet film Kodak made for decades as the workhorse of photomechanical reproduction. The job was narrow. Take a line drawing, halftone screen, or text master, expose it through a process camera, develop in a two-part lith developer like Kodalith Super RT, and produce a negative either fully opaque or fully clear with nothing between. Halftone dots came back razor-edged. Line work came back without a hint of gray.
The orthochromatic sensitization is what made it work in a graphic arts shop. Sensitive to blue and green, blind to red, so a darkroom under a Wratten 1A red safelight was effectively daylit. Nominal sensitivity in lith developer is around ISO 6 to 8 in tungsten, which is why photographers who repurpose it for pictorial work rate it around EI 8 to 12 and develop in a paper developer like Dektol diluted past its label spec to recover gray tones.
The pictorial use case is where 2556 becomes interesting. Shoot a 4x5 sheet at EI 8 in sun, develop in Dektol 1:20 or HC-110 dilution H, and you get a stark, almost engraving-like print with sharp edges and minimal mid-tone information. Compared with Fomapan 100 or FP4+ processed conventionally, the look is unmistakable. There is no shadow detail unless you fight for it. That is the character.
Kodak discontinued 2556 along with most of the Kodalith line in the late 1990s as offset printing went digital. Sheet stock from the 1980s still circulates through eBay and estate sales in 4x5, 5x7, and 8x10. Refrigerated stock holds up well because the orthochromatic emulsion is less prone to long-term fogging than panchromatic film.
Reciprocity exponent is 1.31. Zone Light Meter applies the correction past one second. At ISO 8 in any indoor or studio setting that threshold comes up almost immediately. A metered 15-second exposure becomes roughly 45 seconds at the sheet. Bracket past 30 seconds; the published curve was not characterized for the long pictorial exposures most modern users shoot it for.
How the app handles this stock
- Box speed: ISO 8. 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.