Kodak T-Max 400 (Ektapan 400)

Datasheet-derived original, curve measured. See the notes, the measurement, and the Knowledge base.

Part 0: the last gap in a three-film family

This bank has held T-Max 100 and T-Max P3200 as attributed reference recipes since July 2026. T-Max 400, the middle and by far the most used of the three, sat marked in Film Stocks Master List — the Canon of Top Stocks & Recipe Coverage with its datasheet already archived and never read.

It was the only member of a family the bank half-covered, its evidence was already on disk, and it is the kind of build this bank is strongest at. That is why it kept surfacing as the next thing to do while seven creative looks were built ahead of it.

The film is now sold as Ektapan 400. Eastman Kodak reclaimed the T-Max brand from Kodak Alaris in early 2026 and the whole family was reissued under a revived historic name. The emulsion is unchanged, which is confirmed on Kodak's own still-film index: EKTAPAN is listed as the black-and-white negative family and no T-MAX product tile remains.

Part 1: what the film is, from Kodak's own description

A high-efficiency multi-zone T-GRAIN emulsion with what Kodak calls Optimized Light Filtration technology, claimed as both the world's finest-grained and the world's sharpest 400-speed black-and-white film. Continuous-tone panchromatic, ISO 400, aimed at dim subjects, fast action, extended flash range and scientific work.

The numbers behind the superlatives are in the notes. The short version:

Part 2: the base

Acros against Monochrome is the only real question for a black-and-white recipe here, and Fujifilm's published engineering account settles it the same way it settled Silver Veil.

Acros applies harder compression in the midtone-to-highlight range than plain Monochrome, so detail reads more prominent without any change to dynamic range, and softer treatment in the shadows to preserve detail with depth. Its grain is generated at the file's core rather than overlaid, is tone-differentiated with minimal graininess in the highlights and more in the shadows, and scales with ISO.

Three of those properties map onto this film:

1. Grain that scales with ISO matters more here than on most stocks, because Kodak documents this film across EI 400, 800, 1600 and 3200 on one emulsion. Acros's grain engine tracks that natively, which is why the push variants move the ISO band rather than only the Grain setting.
2. Softer shadow treatment suits a curve whose low end rises gently over a long stretch.
3. Tone-differentiated grain keeps a highlight clean on a film whose whole reputation is cleanliness.

Every other modern T-grain stock in this bank sits on Acros too: Delta 400, Delta 100, XP2 Super. Keeping the family on one base is what makes the differences between them legible.

The filter question, which has no good answer

Kodak states that the blue sensitivity of T-Max films is slightly less than that of other Kodak panchromatic black-and-white films, deliberately, so the response sits closer to the eye's, with the result that blues record as slightly darker tones.

That is a genuine spectral signature and it separates this film from every other panchromatic stock in the bank. The camera cannot model it at the right strength. Acros offers no filter, yellow, red or green, and all three filters are far stronger interventions than "slightly less blue sensitivity". Plain Acros under-models it and Acros+Ye over-models it.

The recipe takes plain Acros and states the gap, which is how Ortho Plus and SFX 200 are already handled here, both flagged partial-fidelity for the same class of reason. The yellow variant exists for when sky separation matters more than emulsion fidelity, and it is labelled as an over-model rather than as a correction.

Worth noting the divergence from the sibling recipe: T-Max 100 is an attributed reference recipe on Monochrome with a green filter, which is a different creator's stylistic route to the same family. This one is derived rather than transcribed, and it lands somewhere else.

Part 3: the tone curve, decided by two manufacturers' own numbers

The useful accident of this build is that both modern T-grain 400-speed films in the bank come with a published average-gradient contrast target for normal development.

• Ilford states Delta 400's plainly, in the development table: "The times in bold will produce negatives of normal contrast (Gbar 0.62)." That number is what justified Delta 400 running at Highlight −1 with Shadow +1, a notch firmer than HP5.
• Kodak does not print a single figure for T-Max 400, but it plots Contrast Index against development time for five developers, and reading each at its own recommended time gives 0.559 with a standard deviation of 0.007.

So the comparison is between two manufacturers' own definitions of a normal negative, and T-Max is the softer.

That has to be handled carefully. Gbar and Contrast Index are similar measures rather than identical ones, defined by different companies over density ranges that are not guaranteed to match. The direction is well supported and the exact percentage is not, which is why the recipe encodes it as a notch at each end rather than as arithmetic:

Softer at the top, and declining the shadow firming that Delta 400's higher target justified.

The shape argument, which points the same way

Two direct readings from the traced curve support the same values without going near the contrast comparison.

The curve keeps climbing to the edge of Kodak's plot with its slope eased only about fourteen per cent from maximum. There is no meaningful shoulder in the published range, so a highlight has nothing protecting it. Negative Highlight and DR400 have to do that job, and −1.5 rather than −1 follows.

The low end rises gently across a long stretch before the curve reaches its steepest section, which is only 2.9 stops wide. A film whose shadows separate slowly does not want its shadow end firmed, so Shadow sits at 0. Acros's own soft shadow treatment reinforces that rather than fighting it.

Part 4: the settings that break house rules, and why

Sharpness +2. The standing rule here is restraint, because the X-T5 has no optical low-pass filter and therefore shows sharpening artefacts earlier than a OLPF body would. Every 400-speed film in this bank sits at 0 or +1, and the only two recipes anywhere here at +2 are a 50-speed and a 80-speed film chosen for exactly that property.

The justification is a first-party superlative with a figure attached: world's sharpest 400-speed black-and-white film, 200 lines per millimetre at a 1000:1 test-object contrast, from an emulsion sold on rendering distinct edges and fine detail. The entire reason this film exists is hundred-speed image structure at four hundred speed, and a recipe that renders it at +1 has thrown away the thing being emulated.

It is also the value most likely to move once frames exist, and the recipe says so.

Exposure compensation upward for contrast. Almost every recipe in this bank pulls exposure down when a scene is contrasty, to protect the top end. Kodak's sheet says the opposite for this film: "For high-contrast scenes, you'll get highest quality if you increase exposure by one or two stops and process the film normally."

That is not a quirk, it follows from the curve. With no shoulder in the plotted range, density keeps separating at the top, so more exposure buys more highlight information rather than less. The camera's version is DR400 and Highlight −1.5 doing the protecting while exposure goes up, and it is stated as a pro tip because it will look wrong to anyone applying the bank's usual habit.

Clarity 0 despite edge-detail language on the sheet. Sharpness +2 is already carrying the acutance claim, and doubling it would cost HEIF safety and shot-to-shot speed for no documented gain. This follows Delta 400's reasoning, where Clarity stayed at 0 because the datasheet carried no explicit edge-contrast statement of the kind Pan F Plus 50's does.

Part 5: where it sits in the bank

Four 400-speed black-and-white recipes now, and they no longer overlap.

It is the cleanest and sharpest of the four and the softest in contrast, which is a combination none of the others offers and which is exactly what Kodak built.

It also closes the T-Max family: 100 and P3200 as attributed references, 400 as a datasheet-derived original.

Part 6: honest limits

• No scan, and no test shots. The measurement is of the film. Nothing has been checked against a negative or a frame.
• The measurement instrument has no external calibration. The curves were read as vector coordinates rather than traced from pixels, which is a better instrument in every respect except the one that matters most: the Double-X calibration standard has raster curves, so the new route cannot be run on it. The internal five-developer convergence in the notes is strong, and it is not the same as ground truth.
• Not placed in the contrast ladder for that reason. That table already warns it compares two tracers and this would make three.
• The Gbar-versus-Contrast-Index comparison supports a direction and not a percentage, as Part 3 says.
• The spectral signature is not modelled, only recorded.
• The translation from a film's measured gamma to a simulation's Highlight and Shadow values is argued rather than measured, and no characteristic curve exists for any film simulation. That is the bank's standing weak link and it applies here in full.

Last updated: 2026-08-26

Research-backed original, derived from Kodak's own datasheet (archived, publication F-4043, February 2016). The world's finest-grained and sharpest 400-speed black-and-white film by Kodak's own claim, and the last member of the T-Max family this bank was missing. Measurement in the notes, derivation in the notes.

Now sold as Ektapan 400. Eastman Kodak reclaimed the T-Max brand from Kodak Alaris in early 2026 and the family is distributed as Ektapan 100, 400 and P3200. Same emulsion, new box. See Film Stocks Master List — the Canon of Top Stocks & Recipe Coverage.

What the datasheet actually says, and what each number bought

Sharpness +2, which no other 400-speed film here gets

Kodak's claim is a superlative and it comes with a number: "World's sharpest 400-speed black-and-white film", at 200 lines/mm resolving power against a 1000:1 test-object contrast, from an emulsion Kodak markets on "Optimized Light Filtration technology" that "renders distinct edges and fine detail".

Every other 400-speed stock in this bank sits at Sharpness 0 or +1. The only two recipes here at +2 are Pan F Plus 50 and Ortho Plus 80, both slow films chosen for exactly this property. That is the point of T-Max 400: hundred-speed image structure at four hundred speed.

The house rule about restraint still applies, because the X-T5 has no optical low-pass filter and shows sharpening artefacts early. +2 is a deliberate departure justified by a first-party superlative and a hard figure, and it is the single setting most likely to need pulling back once frames exist.

Clarity stays at 0 despite the edge-detail language, because Sharpness +2 is already carrying that claim and doubling it would cost the recipe its HEIF safety and its shot-to-shot speed for no documented gain.

The tone curve is softer than its closest rival, on both makers' own numbers

This bank already holds the other modern T-grain 400. The comparison is unusually clean because both manufacturers publish an average-gradient contrast target for normal development.

T-Max is the softer of the two by both makers' own reckoning, and it is measurably the finer-grained and sharper. So it sits a notch gentler at both ends of the curve than Delta 400 does, and a long way cleaner.

Gbar and Contrast Index are similar measures rather than identical ones, so the gap is a direction rather than a precise ten per cent. The direction is what the settings encode.

No shoulder, which changes how you expose it

The traced curve keeps rising to the edge of Kodak's plot at log H +0.4, with its slope easing only about fourteen per cent from the maximum. There is a gentle shoulder rather than a hard one, and nothing that self-protects a highlight.

Kodak's own instruction follows from that and is worth quoting because it inverts normal practice: "For high-contrast scenes, you'll get highest quality if you increase exposure by one or two stops and process the film normally."

On film that works because density keeps separating up there. On the camera the equivalent is DR400 plus Highlight −1.5 doing the protecting, and exposure compensation going up rather than down when the scene is contrasty. That is the opposite of what most recipes in this bank ask for.

The spectral limit, stated rather than glossed

Kodak: "The blue sensitivity of KODAK PROFESSIONAL T-MAX Films is slightly less than that of other Kodak panchromatic black-and-white films. This enables the response of this film to be closer to the response of the human eye. Therefore, blues may be recorded as slightly darker tones with this film", which Kodak calls "a more natural rendition".

That is a real, deliberate spectral property and the camera cannot model it at the right strength. Acros takes no filter, a yellow filter, a red one or a green one, and all three filters are far stronger than "slightly less blue sensitivity". Plain Acros under-models it. Acros+Ye over-models it.

This recipe takes plain Acros and records the gap, which is how the bank already handles Ortho Plus and SFX 200. The yellow variant below is there for when sky separation matters more than fidelity.

Variants

Validation tier: datasheet, curve measured. Kodak's own Contrast Index chart read at five developers, the characteristic curves extracted as vector coordinates rather than traced from pixels, image-structure figures taken from the published table, and the spectral behaviour quoted first-hand. Method, numbers and limits in the notes. No real-film scan yet, and none of the tone values has been checked against a frame.

The highest-value addition would be a T-Max 400 scan at box speed under mixed reportage light.

Pro tip: expose up for contrast, not down (measured 2026-08-26). This film has no meaningful shoulder inside Kodak's plotted range, so highlights keep separating instead of compressing. Kodak's sheet says to add one or two stops for high-contrast scenes and develop normally. Nearly every other recipe in this bank asks you to pull exposure down to protect the top end. This one does not, and the reason is in the curve.

Pro tip: Sharpness +2 is the film, not a preference. Kodak claims the world's sharpest 400-speed black-and-white emulsion and backs it with 200 lines/mm at a 1000:1 test-object contrast. No other 400-speed film in this bank goes past +1, and the only two recipes here that reach +2 are a 50-speed and a 80-speed film. If it reads harsh on your subject, that is the point of the emulsion arriving intact.

Pro tip: it is the soft T-grain 400, which surprises people. Ilford states Gbar 0.62 for Delta 400 and Kodak's own chart puts T-Max 400 at Contrast Index 0.56 across five different developers. Reach for Delta 400 when you want the firmer negative and this one when you want the longer, gentler scale with the finer grain.

Naming note: Kodak now sells this emulsion as Ektapan 400. The rename happened in early 2026 when Eastman Kodak reclaimed the brand from Kodak Alaris. The film material is unchanged, so every setting above still holds.

The numbers behind the notes, the method that produced them, and what the method cannot support. Source: Kodak publication F-4043, February 2016, archived at the datasheet archive.

1. A new instrument: vector extraction rather than pixel tracing

This bank's Measuring film curves from datasheets — method, calibration, and its limits established method renders a datasheet page to a bitmap at 300 to 400 dpi, thresholds it, finds dark runs per column and tracks curves outward from a seed. It works, it is calibrated against Double-X, and it has produced every gamma in this bank so far.

The T-Max 400 sheet does not need it. Kodak drew these charts as vector paths, so the curve coordinates are in the file. They can be read out directly, with no rendering, no thresholding, no run-length filtering and no tracking heuristics. Three of the four failure modes the bitmap method guards against cannot occur.

Axis calibration is still required and is still done from the tick labels rather than assumed:

The honest problem with the new instrument

It cannot be validated against this bank's ground truth. The calibration standard is Double-X 5222, whose datasheet prints five known gammas, and whose curves are raster images rather than vector paths. The vector route cannot be run on it.

So the numbers below rest on internal consistency rather than on the external calibration every other gamma in this bank inherits. Section 3 is that internal check, and it is a strong one, but it is not the same thing and the difference is recorded rather than smoothed over.

Consequence for the contrast ladder: T-Max 400 is not placed in it. That ladder already carries a warning that it compares figures from two different tracers. This would make three, on an instrument with no tie to the calibration standard, and the ladder's whole value is that its entries are comparable.

2. Gamma, and its estimator sweep

Curves from chart F4043C: daylight exposure, D-76, small tank, 20 °C (68 °F), diffuse visual densitometry, plotted at 6, 8 and 11 minutes.

Estimator is the bank's calibrated one: steepest linear fit over a fixed 0.8 log-exposure window.

Swept across five window widths, per §6 of the method file:

The first two are stable to within a few per cent, which is what the method predicts inside its calibrated range of γ 0.50 to 1.05. The 11-minute curve sits at the very top of that range and its 11 % spread is the expected onset of the drift §3 of the method file describes.

Recommended development is D-76 small tank at 68 °F for 7½ minutes, from the sheet's own processing table. Interpolating between the 6 and 8 minute curves gives γ ≈ 0.69, and that is the figure the recipe is built on.

3. The internal check: five developers, one contrast

Kodak plots Contrast Index against development time on the same sheet (chart F4043G, small tank, 20 °C) for five developers. The sheet separately publishes each developer's recommended time at 68 °F.

If both charts and the axis calibration are right, then reading each developer's curve at its own recommended time must give the same contrast, because all five are the manufacturer's definition of normal development for one film.

Mean 0.559, standard deviation 0.007, range 0.552 to 0.568. A spread of 1.3 %.

That result does three things at once. It confirms the axis calibration, it confirms that the five unlabelled paths were assigned to the right developers (they were matched by the order in which their plotted spans start, and a wrong assignment would not converge), and it establishes Kodak's own normal-development target for this film without any estimator at all.

Gamma against Contrast Index

Traced γ ≈ 0.69 at 7½ minutes. Kodak's CI at the same point 0.568. Ratio 1.22.

That is the expected relationship rather than a discrepancy. Contrast Index is an average gradient over a density range chosen to represent the useful printing scale, and it deliberately includes part of the toe. A maximum straight-line gamma is measured on the steepest section only, so it reads higher. A ratio near 1.2 between the two is ordinary.

Both figures are quoted in the recipe, each labelled with what it is.

4. Direct readings, no estimator involved

From the 8-minute curve, which brackets the recommended 7½ minutes.

The fifth row is the one with a consequence. The curve is still rising at the edge of Kodak's plot, with the slope eased by only about 14 % from its maximum. There is a gentle shoulder rather than a hard one, and no self-protection for a highlight.

Stated carefully: this is within the plotted range. Kodak stops at log H +0.40 and what the emulsion does beyond that is not shown. The claim is that no shoulder appears in the range Kodak chose to publish, not that the film has none.

That measurement is what licenses the recipe's inverted exposure advice, and it agrees with Kodak's own written instruction to add one or two stops for high-contrast scenes and develop normally.

5. Figures taken from the published tables

No measurement involved. These are printed.

The 48 µm aperture matches the convention this bank already uses for Post-Production Film Grain — deriving settings from datasheets post-production grain scaling, so the granularity figure is directly comparable to the other stocks measured that way.

6. What this does not support

• No external calibration. Section 1. The vector instrument cannot be run on Double-X, so these figures inherit no tie to the five known gammas that license every other measurement in this bank.
• No place in the contrast ladder, for the same reason.
• Gbar against Contrast Index is a direction, not a percentage. Delta 400's Ilford-stated Gbar 0.62 and this film's Kodak-stated CI 0.559 are similar average-gradient measures defined by different manufacturers over ranges that are not guaranteed identical. That T-Max is the softer of the two is well supported. That it is exactly ten per cent softer is not.
• No scan. Nothing here has been checked against a real negative, and the entire tone-curve translation from a film's gamma to a simulation's Highlight and Shadow values remains the bank's standing weak link.
• The spectral behaviour is not modelled. Recorded in the recipe as a stated limit rather than approximated with a filter that would overshoot it.
• Nothing here measures Acros. The film is measured. The simulation is not, and no characteristic curve exists for any film simulation. The mapping between the two is argued, not measured.

Last updated: 2026-08-26