AP's Portra

Original design (field-test pending). See the notes and the Knowledge base.

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Part 1: The existing Portra recipes, audited against the datasheet

Five Portra-family recipes live in this bank. Checked against Kodak E-4050 (Portra 400, Jan 2025) and E-4040 (Portra 800):

Grain setting	What the datasheet says	Verdict
Weak, Small	"World's finest grain high-speed colour negative film." Print Grain Index 37 at 4×6 from 35mm; threshold of visibility is 25	✅ Emulsion-faithful. Grain present but barely — correct.
Strong, Small	same	❌ Grainier than spec. Models the scanned Portra look seen online, not the film. Already flagged in VALIDATION-AUDIT.
Weak, Small	Portra 160, finest grain of the family	✅ Consistent.
Strong, Large	E-4040 specifies "very fine grain"	❌ Badly overstated — reads like a 1600–3200 stock. Also stacks Highlight —onto Classic Chrome's already-soft highlight end, which is why it can go milky.
Weak, Small	n/a — not strictly a Portra emulation	✅ (see Part 2)

The pattern: the popular recipes chase the scan, the originals chase the emulsion. Both are legitimate targets, but they should be named honestly. Most people's mental image of "Portra" is a lab scan with grain dialled up, not the film Kodak actually specifies.

What the datasheet says Portra is for

Worth quoting, because it reframes the whole exercise:

"KODAK PROFESSIONAL PORTRA 400 is the world's finest grain high-speed colour negative film. At true ISO 400 speed, this film delivers spectacular skin tones plus exceptional colour saturation over a wide range of lighting conditions... the ideal choice for portrait and fashion photography, as well as for nature, travel and outdoor photography, where the action is fast or the lighting cannot be controlled."

Feature list: "Optimized Emulsion Spectral Sensitivity and Image Modifier Chemistry → Beautiful, natural skin tones and superb colour reproduction." It also incorporates Kodak VISION (cinema) film technology, the same lineage as the Vision3 stocks behind this bank's cinema recipes.

"Spectacular skin tones" + "lighting cannot be controlled" is a fair description of the brief: portraits, on a Mumbai street, in light nobody chose.

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Part 2: Why Reggie's Portra is the most popular recipe in the world

Reggie Ballesteros' recipe has sat at or near #1 on Fuji X Weekly for years. Reading it against Fujifilm's published curve data, the reason is clear, and it is not fidelity. It isn't really a Portra emulation at all. It's the most forgiving recipe anyone has published.

Setting	What it actually buys
Shadow —	The secret sauce. Classic Chrome's shadow end is documented as hard — second-hardest tonality of any sim. Shadow —corrects the base's single worst trait, so faces hold detail in bad light.
Highlight —	Classic Chrome's highlight end is already soft; —is the sanctioned amount. Going further (as Portra 800 v3 does at −2) is where recipes go milky.
Auto WB	Works in any light. Most Portra recipes lock to Daylight or 5200K and only truly work in one condition.
DR-Auto	No forced ISO 500 floor, so it works indoors and at night as well as in sun.
—	Fast shot-to-shot saving, HEIF-safe, no skin-texture penalty. A "shoot all day" choice.
Sharpness —	Kind to skin, kills digital edge.
Color —+ CCE —	Richness sourced from gradation (CCE) rather than raw saturation — Classic Chrome has the lowest saturation of any sim, so —is a correction from a floored baseline.
No fixed exposure comp	"Judge each scene." It demands no discipline from the user.

The through-line: every single choice removes a constraint. Auto WB removes the light constraint. DR-Auto removes the ISO constraint. — removes the speed and format constraint. No fixed EC removes the technique constraint. Shadow —emoves the base's shadow flaw.

That is why it wins on popularity. Versatility beats fidelity for daily use, and Reggie's is the most versatile recipe published. It's less a Portra emulation than an extremely well-judged all-round portrait look wearing the Portra name.

The finding that matters for this recipe: Reggie's Shadow —happens to be the exact correction darker skin needs on Classic Chrome. Whether that was intentional or intuitive, it's a large part of why the recipe reads well across a far wider range of skin tones than most. AP's Portra takes that insight further, and then questions the base itself.

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Part 3: Where Indian skin actually sits, and why the base is the problem

Kodak E-4050's density table, the same structure found in the UltraMax sheet:

Area measured	Density	Above grey card
Grey card (grey side)	0.77–0.87	—
Normally lit forehead, light complexion	1.08–1.18	≈ +0.31
Normally lit forehead, dark complexion	0.93–1.03	≈ +0.16

Darker skin renders at roughly half the separation from mid-grey that lighter skin does. On a digital tone curve, that puts it in the lower-mid zone, and whatever the curve does there is what decides between "modelled" and "muddy."

An aside worth noting: Portra's tolerances are 3–4× tighter than UltraMax's

	Portra 400 (pro)	UltraMax 400 (consumer)
Light complexion	1.08–1.18 (range 0.10)	1.10–1.40 (range 0.30)
Dark complexion	0.93–1.03 (range 0.10)	0.85–1.25 (range 0.40)

Same manufacturer, same measurement, radically different tolerance. Portra is precise about skin; UltraMax is forgiving about it. That is the professional-versus-consumer distinction expressed as actual numbers, and it's a genuinely useful thing to know when choosing which film's behaviour to emulate: Portra rewards getting exposure right; UltraMax forgives getting it wrong.

The base collision

Cross the density finding with Fujifilm's published tonality data:

Base	Shadow-end behaviour (Fujifilm's own words)	Consequence for skin in the lower-mid zone
Classic Chrome	"The shadow end is hard" — second-hardest tonality of any sim	✗ Compresses exactly where darker skin sits
Reala Ace	"Deep, soft shadows and hard highlights"	✓ Gradation retained, with depth
Astia	Soft at both ends, saturation maintained; darker skin gets increased saturation	✓✓ but a slide-film character, not a negative
Classic Negative	Cyan-green shadows, magenta highlights	✗ Doubles the sallow and ruddy risk on olive skin
Pro Neg. Hi	"Boosts contrast, creating shadows even in flat light"	~ Good for flat light; adds contrast where we want gradation

Every popular Portra recipe uses the one base with a documented hard shadow end. For lighter skin sitting at +0.31 above grey, that hardness mostly falls below the face and reads as pleasing contrast. For darker skin at +0.16, the face is in it. It is a tax that lighter skin largely escapes.

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Part 4: Why Reala Ace, and the honest risk

Availability, verified: Reala Ace arrived on the X-T5 with firmware 4.00, June 2024. (This repo's conversion notes previously hedged with "on some bodies/firmware", corrected as part of this work.)

Fujifilm's design statements for Reala Ace, and why each one fits this brief:

1. "Deep, soft shadows and hard highlights", the inverse of Classic Chrome. Soft shadows mean gradation where darker skin lives; deep means it keeps richness instead of washing to grey. This is the primary reason for the switch.
2. "The more saturated the subject, the more muted the colour". Nonlinear saturation compression. Mumbai's tarps, saris and signage get tamed automatically while skin, a low-saturation subject, keeps density. It also inverts what the Color dial does: +Color lifts skin more than the already-saturated background, where on Classic Chrome a Color push lands on the accents. For a portrait-in-a-loud-city, that's exactly the right way round.
3. "Complex-colour reproduction, particularly purple and yellow-green", the hues that defeated traditional negative stock, and a fair inventory of Indian textiles.
4. It is genuinely a negative-film simulation. Reala was a Fujicolor C-neg; Portra is a C-neg. Classic Chrome is based on no analog film at all. Fujifilm calls it "an imaginary film" modelling printed magazine pages. For emulating a negative, Reala Ace is the structurally honest base.

The risk, stated plainly

Reala Ace is the newest simulation in the lineup and has far less published curve data than Classic Chrome, which has multiple X Stories articles dissecting its tonality. The reasoning for choosing it is strong; the specific settings are less battle-tested than a Classic Chrome build would be, simply because fewer people have spent years tuning on it. The repo's own note is also worth heeding: "Reala Ace is a poor base for deliberately vivid looks", which is fine here, because this is a portrait recipe where restraint is the point, but it would be wrong for a street-colour recipe.

That is why the notes ships a Classic Chrome fallback alongside the primary. Not hedging, the fallback is a genuinely good recipe (it's Reggie's logic pushed one step further for darker skin, at Shadow —). But the Reala Ace build is the one worth testing first.

Complementary to AP's UltraMax, not redundant

	AP's UltraMax	AP's Portra
Base	Classic Chrome	Reala Ace
Colour behaviour	+Color lands on accents — they pop out of an earthy frame	+Color lands on skin — the background gets compressed
Built for	The scene: street, chaos, colour as subject	The person: portraits, skin as subject
Contrast	Punch moved into colour	Restraint; gradation protected

Two recipes, opposite mechanisms, same city. Shoot UltraMax when Mumbai is the subject and Portra when someone in it is.

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Part 5: "Is Portra even right?", and what the greats actually shot

The brief invited disagreement, so, honestly:

Portra is a good target and the datasheet backs it. "Spectacular skin tones," "beautiful, natural skin tones," and explicitly designed for "where the lighting cannot be controlled." Wide latitude, fine grain, warm-neutral skin. There is no better-specified portrait negative. The problem was never Portra. It was the base everyone emulates it on.

But if the question is what the greats used for India in colour, the answer isn't Portra. It's Kodachrome.

• Raghubir Singh, who effectively invented Indian colour photography and made Bombay/Mumbai one of his central subjects, shot Kodachrome: at a time when serious photography was assumed to be black and white.
• Steve McCurry's India and South Asia work, including the most famous colour portrait of the 20th century, is Kodachrome 64.

That is a genuinely different aesthetic: high saturation, deep reds, — contrast, archival dyes. It is the look of Indian colour photography as the world knows it. This bank already holds Kodachrome 64 and Kodachrome 25 as reference recipes.

Two honest caveats before chasing it: 1. Kodachrome is contrasty and saturated, the opposite of a gentle portrait film. It made McCurry's portraits iconic through drama, not flattery. 2. The bank's existing Kodachrome 64 recipe runs Clarity —and Shadow —, both actively wrong for darker skin by everything established above. A Kodachrome tuned for Indian skin would need the same treatment this recipe just gave Portra, and it is the obvious next build. (Noted as a follow-up.)

The verdict: Portra for people, Kodachrome for the picture of India. They're different jobs. This recipe does the first one; the second is worth building next.

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Validation status

⚠Original design, field-test pending. Grounded in: 1. Kodak E-4050 datasheet (archived). Complexion density targets, Print Grain Index 37, the "lighting cannot be controlled" design brief, VISION technology lineage. 2. Kodak E-4040 (Portra 800). Used for the grain audit of the v3 reference recipe. 3. Fujifilm's published tonality and colour-design data for Reala Ace, Classic Chrome, Astia, Classic Negative and Pro Neg. Hi. 4. The Mumbai 11-image place study. Palette, haze, warm-in-every-light. 5. A recipe-vs-datasheet audit of all five existing Portra-family recipes here.

Not yet shot on Indian skin, which is the entire premise, the gap that matters. Highest-value test frames, in order: (1) face in harsh midday sun, (2) face in open shade, (3) face under sodium-vapour night light, (4) the same face on both the Reala Ace and Classic Chrome builds, back to back.

The explicitly labelled inference: mapping Kodak's negative-exposure density targets onto a digital tone curve is my reasoning from the data, not a Kodak claim. The direction is unambiguous. Darker skin sits lower on the curve, but the magnitude of the correction is what test frames need to settle.