Ilford Commercial Ortho

Ilford Commercial Ortho was a slow orthochromatic sheet film that lived on the studio table, the copy stand, and the graphic-arts repro bench for most of the twentieth century. Orthochromatic means the emulsion is blind to red. Lay it under a deep red safelight in the darkroom and you can watch development progress with the lights on, which is exactly why technical photographers and printers loved it from the 1920s through the 1970s.

The look the film gave a face is the part still worth knowing. Without red sensitivity, lips render almost black, freckles go dark, blue eyes lighten, and the whole tonal pattern of a portrait shifts. Hollywood and early Ilford studio portraitists used ortho deliberately for that effect before panchromatic stocks took over in the 1930s. Commercial Ortho kept that response on the menu for decades after most photographers had moved on, because copy work, line illustrations, and document reproduction needed exactly that blue-and-green-only sensitivity.

The grain was fine, the resolution was high, and the curve was contrasty in the way copy stand films need to be. Compared with FP3 of the same period, Commercial Ortho rendered with more snap and less midtone gradation. Against Kodak Commercial 6127, the Ilford ran cooler and held a tighter grain pattern in 4x5.

Rated at ISO 80, it was almost always a tripod film. ID-11 was the standard developer; D-76 at 1:1 gave similar results. For copy work most labs ran it in a contrasty bath like Kodak D-11 to push the toe up further.

The film has been discontinued for decades. Surviving sheets surface in estate sales of working printers and graphic-arts studios. Anything not frozen since the 1970s will show heavy base fog and is best reserved for tests rather than final work.

Reciprocity exponent is 1.31. Zone Light Meter applies the correction past one second on the standard silver-grain curve. A 30-second metered reading becomes about 90 seconds at the negative. On a copy stand at f/16, that threshold arrives on the first frame.