Ilford Delta 400

Research-backed original, derived from the Ilford Delta 400 Professional datasheet (archived). Reproduces Ilford's fast T-grain (tabular grain) 400-speed stock: ISO 400, built to hold a documented normal-development contrast target (Gbar 0.62) across a native push range of EI 200-3200 in the same roll. The modern-emulsion counterpart to HP5 Plus 400 at the same box speed. Derivation in the notes.

Why these values (short)

• Acros base: carries real tonal gradation under grain, the house standard for every B&W original.
• Grain Strong, Small: datasheet: a genuine 400-speed film, so grain is visibly present (unlike the Weak/Small tier of Delta 100), but built on the same core-shell T-grain crystal family as Delta 100 and Delta 3200. Finer and more regular than the conventional grain in HP5 Plus 400 at the same speed, hence Small rather than HP5's own "Strong, Small" reading a touch coarser in practice.
• DR400: this stock's native working range is genuinely wide: the datasheet's own development tables run from EI 200 to EI 3200 in one film, with extended development in ILFOTEC DD-X, ILFOTEC HC, MICROPHEN or ILFOTEC RT RAPID explicitly sanctioned for the push end. DR400 protects highlights across that full practical range, more aggressively than HP5's DR200.
• Highlight −1, Shadow +1: the datasheet states a specific development contrast target of Gbar 0.62 ("normal contrast") for standard processing, a firmer, more defined curve than a "forgiving latitude" reading. That's a genuine documented number, not a guess, and it's the reason this recipe sits a notch firmer than HP5's Highlight 0 / Shadow +2, which is built around HP5's reputation for "letting shadows be shadows."
• Sharpness +1: T-grain crystals present a flatter boundary to light than conventional grain, which is the physical basis of tabular-grain films' reputation for higher acutance at a matched speed. A small positive Sharpness reflects that without overclaiming a number the datasheet doesn't state directly.
• Clarity 0: no "edge contrast" language in this datasheet (contrast with Pan F Plus 50's sheet, which states that explicitly), the bank's default holds.
• ISO to 6400: the datasheet's own development-time tables run natively to EI 3200/36, so the digital ceiling is set high, though a notch below Delta 3200's 12800: Delta 400 is a 400-speed film that pushes well, not a push-native 3200-speed stock built around extended development as its whole identity.

Handling

• A 400-speed film that genuinely spans daylight to available-light: the datasheet's own recommended range (EI 200-3200) means this recipe is honestly usable at both ends without switching stocks.
• For the classic, more forgiving reportage read at the same speed, use Ilford HP5 Plus 400, the two sit side by side as "modern T-grain precision" vs "traditional balanced latitude," a real chemistry distinction rather than two names for the same thing.
• For heavier, push-native grain, step up to Delta 3200 or Kodak Tri-X 400.

Validation tier: Datasheet-validated (EI 200-3200 development-time tables, Gbar 0.62 contrast target, T-grain construction, archived PDF). Characteristic pass: consistent with widely-documented T-grain-vs-conventional-grain behaviour at matched ISO 400 speed class. No real-film scan yet. A frame under mixed reportage light, or at a pushed EI, would be the highest-value addition.

Pro tip: "Gbar 0.62" is a real number, use it (2026-07-25). Ilford's own development charts define "normal contrast" for this film as a gamma-bar of 0.62 at box speed in ID-11. That is a firmer, better-specified target than most datasheets state outright, and it is the actual justification for this recipe's Highlight/Shadow values, not a stylistic guess. If a real scan comes in reading softer or harder than this recipe expects, check the stated developer and dilution before assuming the recipe is wrong. See the Validation Methodology. Proof of Faithfulness B&W developer-confounder rule.

ISO 500 is the sweet spot, not a compromise (measured 2026-07-27). DR400 pins the ISO floor at 500, and that is exactly where the X-T5's conversion-gain step sits, so it is the cleanest ISO in that region, not a tax you pay for using DR400. ISO 640 is the expensive next click: roughly 0.35 EV of dynamic range for one third-stop, against about 0.02 EV for the step from 400 to 500. In good light, hold ISO at 500 and control exposure with aperture and shutter. Measured from published read-noise and PDR data, see Dynamic Range & Tone Curve, the contrast controls.

Original (datasheet-validated). See the notes, the B&W README, and the Knowledge base.

The film

Ilford Delta 400 Professional, a fast, fine-grain B&W film on the same core-shell tabular (T-grain) crystal technology as Delta 100 and Delta 3200, positioned by Ilford as "ideal for action and available light photography" while also giving "fine grain results for pictorial and fine art photography." The datasheet (archived, Nov 2018) states a ISO 400/27° speed rating measured in ID-11, with the manufacturer explicitly sanctioning use "at meter settings up to EI 3200/36... Given extended development" in four named developers.

Why this was a gap worth closing

Like Delta 100, this stock sat flagged as a derivation candidate in Film Stocks Master List, the Canon of Top Stocks & Recipe Coverage with its datasheet already archived (fetched 2026-07-15) but never actually read into a recipe. Extracting the primary source turned up a specific, citable number worth having: a real contrast target rather than a speed rating.

The number that grounds this recipe: Gbar 0.62

Ilford's own development-time table states plainly: "The times in bold will produce negatives of normal contrast (Gbar 0.62)." Gamma-bar is a standard sensitometric measure of average development contrast, a firmer, more precisely specified target than most datasheets in this bank provide. That number, not a stylistic guess, is what justifies this recipe running a notch firmer (Highlight −1 / Shadow +1) than HP5 Plus 400's more forgiving Highlight 0 / Shadow +2. Two 400-speed Ilford stocks, two different documented contrast philosophies.

T-grain vs conventional grain, at matched speed

This is the same real distinction found in the Delta 100 knowledge file, just at 400-speed instead of 100: tabular crystals present a flatter, more regular boundary to light than the conventional (cubic) grain in HP5, which is the physical reason T-grain emulsions are documented to read finer and hold higher acutance at a matched box speed. HP5 remains the "classic latitude" choice. Delta 400 is the "modern precision" one. Both are legitimate, and they are genuinely different films, not two labels for the same recipe. See Film Chemistry Fundamentals. Why Film Looks the Way It Does.

The grade in one line

A 400-speed B&W that spans daylight to available-light on its own datasheet's terms (EI 200-3200 in a single film), with a firmer, better-specified contrast target than its "balanced and forgiving" sibling HP5.

vs the rest of the B&W family

See the comparison table in the Delta 100 knowledge file for the full seven-stock picture.

Validation status

Datasheet-validated (EI range, T-grain construction, the Gbar 0.62 contrast target, archived PDF). Characteristic pass strong (T-grain vs conventional-grain behaviour is widely documented and consistent with independent film reviews). No real-film scan obtained yet.