KB17 is one of those films that survives mostly as a name. It was discontinued more than fifty years ago, the company that made it was absorbed into DuPont, and most of its post-war photographic vocabulary — thin layer, fine grain, Schicht-Film — has migrated into the marketing copy of films that have nothing to do with it. But for a window of roughly two decades, Adox KB17 was one of the sharpest 35mm black-and-white films you could buy, and it was one of the films that pushed the rest of the industry toward the kind of resolution we now take for granted.

We currently have a small number of hand-rolled 135 cassettes of KB17 in Film Fridge. The film inside is genuinely old — the bulk roll it came from was loaded long before any of us were keeping notes. This article is meant as context for that stock: who made it, what it actually was, what its contemporaries were, and what to expect from a roll today.

Schleussner, Frankfurt, and the thin-layer revolution

The "Adox" name belongs to Fotowerke Dr. C. Schleussner GmbH, a Frankfurt am Main chemistry firm founded in the late nineteenth century by Carl Schleussner. Schleussner was one of Germany's earliest manufacturers of dry photographic plates and remained a serious technical force in European photography through the first half of the twentieth century — a quieter, more specialist counterpart to Agfa.

The company's lasting contribution was the thin-emulsion film that appeared under the Adox name in the early 1950s. The conventional black-and-white films of the era were, by today's standards, thick: the silver-halide emulsion was coated heavily on the base, which gave the film a wide tonal range and a certain look, but at a cost. Light traveling through a thick emulsion scatters. The image picks up a small halo at the grain level, which softens the appearance of fine detail. Resolving power and acutance suffer.

Schleussner's response was to coat a noticeably thinner emulsion on a hardened base. Less depth meant less internal scatter, finer perceived grain, and an apparent sharpness that was unusually high for the speeds involved. The trade-offs were a slightly more delicate latitude and the need for careful handling, but the gain in image quality at the negative was visible in the print.

This was, in 1952, an obviously different way of building film. American distributors started calling it the German wonder film, and the marketing stuck.

The KB family

The thin-emulsion line was sold internationally as the "KB" series — German shorthand for Kleinbild, "small picture," meaning 35mm. The numerals refer to the DIN sensitivity rating, not to ASA:

• KB14 — 14° DIN / ISO 20. The slowest of the family; extreme fine grain, used for copying and exacting fine-art work.
• KB17 — 17° DIN / ISO 40. The middle stock and all-purpose member of the family; the most widely sold.
• KB21 — 21° DIN / ISO 100. Faster and slightly grainier, but still finer-grained than most 100-speed competitors of the era.

KB17 was also produced in 120 roll film and as sheet film. The 35mm version is by far the most encountered today; the roll-film and sheet versions are properly rare.

The classical period for the KB family runs roughly 1952–1973, with the bulk of the German-made production concentrated before the late 1960s.

Sensitisation and tonal character

KB17 was a panchromatic emulsion, but with the slightly muted red sensitivity typical of pre-modern panchromatic stocks. In practice this meant skies that didn't render quite as bright as a modern film would render them, skin that looked a little more architectural, and a rendering of foliage that fell somewhere between the deep blacks of a true ortho film and the lighter greens of fully panchromatic emulsions.

Tonally, the film is honest rather than dramatic. The native curve is fairly straight in the midtones, with shoulders and toes that compress gracefully. There's no exaggerated highlight glow, no aggressive shadow lift. With normal development in any standard fine-grain developer of the period — D-76, ID-11, Atomal, Microdol-X — KB17 produces negatives that print easily on a normal-grade paper.

Resolution is the headline. With clean technique on a tripod and decent glass, KB17 will outresolve most contemporaneous 35mm films at its speed range. It will not match Kodak Technical Pan, which came twenty years later and was engineered for a different ceiling — but among general-purpose pictorial films of the 1950s and 1960s, the KB family is at the top end. (For more on Technical Pan as a comparison point, see our notes on a discontinued classic.)

What else looked like KB17 at the time

KB17 didn't exist in isolation. Several of its contemporaries are worth knowing about — partly because period photographers often used them interchangeably, and partly because we keep an eye out for them at the Optics Lab.

Agfa Isopan F (ISO 25) and Isopan FF. Agfa's slow-to-medium-speed B&W films of the 1950s and 60s. Isopan F was the natural German rival to KB17 — slightly slower, slightly more contrast in the highlights, and the more commonly encountered of the two in West German camera bags of the period. Agfa's later Agfapan line eventually replaced the Isopan series.

Perutz Persenso and the NP series. Perutz, a Munich-based firm, made very competent fine-grain panchromatic films into the 1970s before being absorbed by Agfa. Persenso 17 and the NP15/NP22 stocks are stylistic cousins of KB17 — slightly warmer in tone, slightly more forgiving in latitude, and increasingly hard to find today.

ORWO NP15 and NP20. Made in Wolfen by what had been the Agfa film plant before partition, ORWO continued the Agfa Isopan lineage on the East German side of the Cold War. NP15 (ISO 25) is the closest emotional analogue to KB17 — a slow, sharp, classical European emulsion with a darker shadow rendering.

Ilford Pan F (ISO 50). The British comparison. Pan F was — and is, in its modern Pan F Plus form — a slow, fine-grain panchromatic. The original Pan F has a tonal palette that is close enough to KB17 that prints made under the same enlarger and paper can be hard to tell apart at small sizes. We have a few hand-rolled cassettes of the original Pan F's stablemate, Ilford FP4, in Film Fridge.

Kodak Panatomic-X (ISO 32, originally 25). The American slow-speed standard for decades. Panatomic-X was discontinued in 1987 and is, on average, less sharp than KB17 but with more printing latitude and a slightly creamier shadow rendering. Many photographers who grew up shooting Panatomic-X find KB17 immediately legible.

Kodak Plus-X Pan (ISO 125). Faster than the KB family, but routinely paired with KB17 in working photographers' film holders for low-light situations. Plus-X is closer in character to KB21 than to KB17.

We do occasionally come across rolls of these stocks. When we do, they tend to find their way into Film Fridge alongside the KB17. If you're curious whether we have any in stock right now, the film page is the source of truth — the inventory there is updated as rolls move.

The DuPont takeover and the long decline

In 1962, DuPont acquired Schleussner's photochemical operations. DuPont kept the Adox name in the United States for a period and continued to produce films under the brand, but the products coming out of the American plant were not the same as the German originals: different bases, different coatings, and a reputation that quickly soured among photographers who had bought into the original wonder-film promise.

By the early 1970s, Adox-branded films had largely disappeared from the European market. Production of the original KB family ceased around 1973. What remained was the manufacturing equipment — the coating machines, the formulas, the institutional knowledge — and a question of who would inherit it.

Efke, Croatia, and the second life

The answer was Fotokemika, a film manufacturer in Samobor, near Zagreb in what was then Yugoslavia (now Croatia). In the 1970s Fotokemika acquired both the equipment and the recipes, and the original Adox emulsions continued to be coated on the original machines under the Efke brand.

Efke KB14, KB25, KB50, KB100 — the names are direct lineal descendants of the Adox KB family, although by then the numbering had drifted from DIN toward ISO. The film stock, particularly through the 1980s and into the 2000s, was effectively the same emulsion, slightly modernised. For a long time Efke films were the only way to shoot a recognisably "Adox-style" thin-layer film on the open market.

Fotokemika closed in 2012, ending the original lineage definitively. The machines did not move. The recipes did not transfer. There is no longer any factory anywhere in the world producing a film derived directly from the original 1950s Schleussner emulsions.

The modern ADOX brand

The current company trading as ADOX, based in Bad Saarow east of Berlin, is a different organisation. It was rebuilt from the trademark up in the early 2000s by Mirko Böddecker of Fotoimpex, and produces a serious and growing lineup of black-and-white films — CHS 100 II, CMS 20 II, Silvermax, Scala 50, HR-50 — alongside chemistry and paper.

Modern ADOX films are not the same as KB17. They are coated in different facilities, on different bases, using different silver-halide structures. CMS 20 II is closer in spirit than anything else on the market — an extremely fine-grain, high-resolution emulsion designed for technical and pictorial use — but it is its own film, not a continuation. The continuity is in the name and in the philosophy: thin emulsion, fine grain, sharp negatives, made in Germany.

That distinction matters when you handle a roll of original KB17. The film in the cassette is from a production line that no longer exists, made by a company that no longer exists, on equipment that was scrapped in Croatia in 2012. There is a finite, slowly diminishing amount of it in the world.

Shooting our hand-rolled KB17 today

The KB17 we sell is hand-rolled — bulk-loaded into 135 cassettes from a longer reel of stock. We don't have an original Schleussner box for it; the rolls in the fridge are working photographers' rolls, cold stored, and were almost certainly loaded decades ago.

A few practical notes for anyone shooting it:

Rate it conservatively. The box speed of ISO 40 is the upper bound. For older bulk stock of unknown vintage, we recommend rating it at ISO 25 as a safe baseline, or even ISO 20 if the negatives are coming out thin. Older silver halide emulsions lose effective sensitivity gradually; the film hasn't gone bad, it's just slower than it used to be.

Expect base fog. Panchromatic films that have been sitting on a shelf for thirty or more years tend to develop a low veil of fog across the base. This isn't a defect; it's a fact of age. Slight overexposure helps push the picture-bearing densities cleanly above the fog floor.

Use a fine-grain developer. D-76 stock or 1+1, Atomal, or Microdol-X-style developers are the historically appropriate choices. KB17 in Rodinal will give you a sharper, more granular negative — period photographers used it that way too, and it can be a beautiful look on architecture and stone.

Protect highlights. The native curve is honest but not enormously latitude-rich, and aged stock has even less. Meter for the shadows; let the highlights fall where they fall. Printing on a slightly softer paper grade is often kinder than trying to compress everything in development.

Treat it as a daylight film. This is a slow stock with no special low-light personality. It rewards even, directional daylight, careful tripod work for landscapes and architecture, and a steady hand for street.

We do not carry an original Schleussner datasheet for KB17 — to our knowledge, the period sheets were never digitised in any properly archival form, and what circulates online is fragmentary. If you find a credible scan in the wild, we'd be glad to hear about it.

A curatorial note

We treat KB17 the way we treat any object whose maker no longer exists: with a slight extra care, and with the understanding that we are passing it through, not making more of it.

The film itself is unremarkable to load and unremarkable to shoot. Once it's in the camera it behaves like a slow, classical, mid-twentieth-century B&W film — which is exactly what it is. The remarkable thing is what's behind it: a small German chemistry firm in Frankfurt, a thin-emulsion innovation that pushed the rest of the industry forward, an American takeover that hollowed it out, a Croatian afterlife that quietly ended in 2012, and a German revival that carries the name but not the formula.

If you'd like to take a roll out, we have a small supply in Film Fridge. When it's gone, we'll keep an eye out for more — but we make no promises about replenishment. That's the nature of the stock.

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Adox KB17 is available in Film Fridge while supplies last.