Ilford Delta 100
How this look was derived, and why every control does what it does. The settings themselves are in the pack.
Original (datasheet-validated). See the notes, the B&W README, and the Knowledge base.
The film
Ilford Delta 100 Professional, a medium-speed, fine-grain B&W film built on core-shell tabular (T-grain) crystal technology, the same emulsion family as Delta 3200 but at the opposite end of the speed range. The datasheet (archived: _reference-sources/datasheets/ilford/delta-100.pdf, Apr 2023) states a speed rating of ISO 100/21°, with "good image quality" across EI 50/18 to EI 200/24, a genuinely narrow window compared to the bank's more forgiving stocks, and the datasheet is explicit that this range is "based on a practical evaluation of film speed... not based on foot speed, as is the ISO standard." Ilford positions it plainly: "ideal for pictorial and fine art photography."
Why this was a gap worth closing
the notes had flagged Delta 100 as a ❌ derivation candidate for some time, with a note that its datasheet was "already archived". Meaning the primary source had been sitting in this repo, unused, since the 2026-07-15 datasheet fetch. This recipe closes that gap using exactly the data that was already here.
T-grain vs conventional grain: the real distinction from Acros 100
Delta 100 and Fujifilm Acros 100 share a box speed (ISO 100) and near-identical marketing language ("fine grain," "rich detail"). What's actually different is the crystal geometry. Tabular (T-grain) crystals are flat and regular rather than the irregular cubic crystals of conventional emulsions; a flatter crystal boundary scatters light more predictably, which is the physical basis for T-grain film's reputation of looking smoother rather than "sparkly" at a matched speed, the same structural family Ilford uses at the opposite (3200) end of the Delta range. See film-chemistry-fundamentals.md for why grain size, crystal shape and development chemistry are chemically coupled, not independent style choices.
The Clarity decision: the same standard, honestly applied to different evidence
This bank's rule is — by default, deviating only when the datasheet specifically justifies grit (Tri-X 400's "+3", Pan F Plus 50's "+2" for its own sheet's explicit "edge contrast" language). Delta 100's datasheet does not use that language. So despite Delta 100 and Pan F Plus 50 both being pitched by Ilford as fine-grain precision stocks, only one of them gets a Clarity boost, because only one of them's own paperwork asks for it. That is the validation methodology working as intended: read what the source actually says, not what a similar-sounding stock's recipe already did.
The grade in one line
The quietest, most restrained member of the B&W family, a precision, controlled-light stock positioned between Pan F Plus 50's extreme slow-speed "etched" character and Acros 100's do-anything workhorse versatility, without borrowing either one's specific personality.
vs the rest of the B&W family
| Pan F 50 | Delta 100 | Acros 100 | HP5 400 | Delta 400 | Tri-X 400 | Delta 3200 | |
|---|---|---|---|---|---|---|---|
| True speed | ISO 50 | ISO 100 | ISO 100 | ISO 400 | ISO 400 | ISO 400 | ISO ~1000 (shot at 3200) |
| Grain tech | conventional | T-grain | Fujifilm Acros model | conventional | T-grain | conventional | T-grain |
| Grain (recipe) | Weak/Small | Weak/Small | Weak/Small | Strong/Small | Strong/Small | Strong/Large | Strong/Large |
| Clarity | +2 (edge contrast, datasheet) | 0 | 0 | 0 | 0 | +3 (grit, datasheet) | +1 |
| EI latitude (real film) | narrow | narrowest but one | wide (practical use) | wide | wide (200–3200) | wide, pushable | by-design push (400–25000) |
| Personality | slowest, "etched" | quiet, precise | do-anything workhorse | balanced, forgiving | modern-precision 400 | gritty, contrasty | heaviest, smooth-pushed |
Validation status
Datasheet-validated (ISO/EI table, T-grain construction, reciprocity data, pictorial-photography positioning, archived PDF). No real-film scan obtained yet, the honest state is datasheet-only, one tier below the bank's top standard. A daylight architecture or still-life frame, ideally with a grey card, would be the highest-value addition: drop into references/.
Get Ilford Delta 100
Every value, the movie-mode translation, and the datasheet evidence behind the grade.