Film · Updated
Kodak Tri-X 400
The film, its filters, and how it is pushed.
Kodak Tri-X 400 (Kodak’s code 400TX) is an ISO 400 black and white negative film, sold in 35 mm and 120 since 1954 and for decades the film of news and street photographers. It is panchromatic, sensitive to every color, and sees blue more strongly than the eye does, so an unfiltered sky prints pale; a yellow, orange or red filter darkens it. Its curve is a long toe and then a straight line with no shoulder, and it takes a push well: Kodak gives development times for EI 1600 and 3200. Kodak calls its grain fine, with an rms granularity of 17.
Below: Kodak’s datasheet in a table, the film’s history, what it looks like and why, filters, pushing it, Tri-X against HP5 Plus, recipes, and Street 400 (based on Kodak Tri-X 400), the Clack film modeled on it.
01 · The film
Tri-X 400 by Kodak’s datasheet
| Type | Black and white negative film, panchromatic; Kodak’s code 400TX |
|---|---|
| Speed | ISO 400; push times for EI 1600 and EI 3200 in the sheet |
| Sizes | 135 and 120, and a single-use camera (27 exposures, 30 mm f/10 lens) |
| Grain | Diffuse rms granularity 17, which Kodak calls “fine” (HC-110 dilution B, a 48 µm aperture, at a density of 1.0) |
| Development | Aimed at a contrast index of 0.56: T-MAX developer 6 min, D-76 6¾ min (small tank, 20 °C) |
| Bright sun | 1/500 s at f/16 with distinct shadows: the sunny 16 rule |
| Long exposures | 1 s metered: give 2 s and develop 10 % less; 10 s: 50 s and 20 % less; 100 s: 1200 s and 30 % less |
From Kodak’s technical data F-4017 (October 2021). Kodak: “Fine grain”, “wide exposure latitude”, “high sharpness”, and “recommended for push-processing applications”. The sunny 16 rule and its arithmetic are in the sunny 16 calculator.
02 · History
Tri-X: 1940 to today
Kodak introduced Tri-X around 1940 as a sheet film, rated ASA 200 in daylight. The 35 mm and 120 rolls came in 1954, and fast film in a small hand-held camera changed photojournalism: Tri-X became one of its most used films. In 2007 Kodak re-engineered it, with less silver and finer grain, and changed its code from TX to 400TX. It is sold today as Kodak Professional film by Kodak Alaris, which publishes its datasheet.
03 · The look
What Tri-X 400 looks like, and why
A black and white print of Tri-X comes from three things: how the film turns color into gray, the negative’s curve, and the paper it is printed on.
- Blue counts more, green less. Kodak’s spectral sensitivity is flat through blue and green and falls away past about 650 nm. Weighed against a daylight scene, the film takes red, green and blue about 0.21, 0.37 and 0.42, where the eye’s brightness takes them 0.21, 0.72 and 0.07 (our arithmetic). So with no filter blue sky prints light, and greens and reds a little dark.
- A long toe, no shoulder. The shadows climb out of the film’s base slowly, then the curve runs straight past the top of Kodak’s chart. Highlights do not compress on the negative; the paper decides where white is.
- The print sets the contrast. Kodak develops it to a contrast index of 0.56, a negative for the middle paper grade. A printer chooses a harder or softer grade to suit; Clack prints Tri-X on grade 3, half a grade harder than the middle of a multigrade paper’s 0 to 5.
- Fine grain, by Kodak’s word. An rms granularity of 17; a push, Kodak says, makes it grainier. More in what is film grain.
- No halation to speak of. One silver layer on a gray base, so bright lights do not get the red rim of color film. More in what is halation.
04 · Filters
Yellow, orange, red and green filters on Tri-X
On black and white film a color filter lightens its own color and darkens its opposite. A yellow filter holds back some blue, so the sky darkens and clouds stand out; orange more; red turns a blue sky dark and lightens skin and red things. Green lightens foliage and darkens red. A filter also costs light, which the filter factor gives: a factor of 2 is one stop more exposure, 8 three stops. A camera that meters through the lens makes most of it up itself.
| Filter | Kodak’s daylight factor | In Clack’s model | What it does |
|---|---|---|---|
| Yellow, No. 8 | 2 (1 stop) | 2.25 | Sky a little darker, clouds stand out |
| Yellowish green, No. 11 | 4 (2 stops) | Not in Clack | — |
| Orange, No. 21 | Not listed | 3.7 | Sky darker, skin smoother |
| Red, No. 25 | 8 (3 stops) | 7.1 | Sky dark, red and skin light, blue near black |
| Green, No. 58 | 6 (2⅔ stops) | 9.5 | Foliage lighter, red dark |
| Blue, No. 47 | 6 (2⅔ stops) | Not in Clack | — |
| Polarizer | 2.5 | Done by color | Blue sky and water darker |
Kodak’s factors are from F-4017. Clack’s column is the factor its model implies from Kodak’s WRATTEN 2 filter curves through Tri-X’s sensitivity in daylight (our arithmetic); the green comes out higher than Kodak’s, and Kodak lists no orange for Tri-X.
05 · Pushing
Pushing Tri-X 400 to 1600 and 3200
To push a film is to rate it faster and develop it longer. Kodak, in F-4017: “Because of these films’ exposure latitude, you can underexpose by one stop and use normal processing times. Prints will show a slight loss in shadow detail.” Two stops under (EI 1600) needs a push; prints show “an increase in contrast and graininess with further loss of shadow detail”, acceptable “for many applications”. Three stops (EI 3200) is acceptable “for some applications”.
| Developer | EI 400 | EI 1600 (push two) | EI 3200 (push three) |
|---|---|---|---|
| T-MAX | 6 | 8¾ | Not recommended (8¼ at 24 °C) |
| D-76 | 6¾ | 9½ | 11 |
| XTOL | 7 | 9¾ | 11½ |
| HC-110 (B) | 3¾ | 6 | None given |
Kodak’s times in minutes for Tri-X 400 in a small tank at 20 °C (68 °F), agitated every 30 seconds (F-4017). Kodak gives no time for EI 800; it develops normally. The push to 1600 raises the contrast index to 0.72, against 0.56.
“Tri-X 3200” is Tri-X rated at 3200 and pushed three stops, on Kodak’s EI 3200 times.
06 · Against
Tri-X 400 vs HP5 Plus 400
Ilford HP5 Plus is the other fast black and white film most photographers know, and the one Tri-X is most often set against. By the two makers’ own sheets they are close: at each maker’s normal development the curves have one shape, a long toe then a straight line, and HP5 Plus is a touch harder, about a quarter of a paper grade. The real difference in the data is color: HP5 Plus prints greens lighter and reds and blues darker.
| Kodak Tri-X 400 | Ilford HP5 Plus 400 | |
|---|---|---|
| Maker | Kodak, sold by Kodak Alaris | Ilford, by HARMAN technology |
| Speed on the sheet | ISO 400; push times to EI 3200 | ISO 400; “good results” from EI 400 to 3200 |
| Contrast at the maker’s normal time | Contrast index 0.56 (T-MAX 6 min, D-76 6¾ min) | 0.59 in ID-11, 7½ min (our arithmetic, by Kodak’s method) |
| Grain figure | Diffuse rms granularity 17, “fine” | None published, only “fine grain” |
| Base plus fog | About 0.29 in D-76 | 0.17 |
| Color into gray | Reds and blues about 0.2 stop lighter than HP5’s | Greens about 0.2 stop lighter than Tri-X’s |
| As photographers tell them | Harder, “punchy” | Softer, flatter |
Kodak’s F-4017 and HARMAN technology’s HP5 Plus sheets (2018, 2010, 1998), read off their curves; the contrast and color rows are our arithmetic on those curves. A printer light or a scanner’s black point takes out the base’s difference.
The common story, Tri-X punchy and HP5 flat, is not in either maker’s curves at its own times. It may come from scans leveled frame by frame, other developers and times, or pushes; that is not established. Reviewers split on grain too: RI Film Lab and Analogue Wonderland call Tri-X’s grain chunkier or more distinctive and HP5’s finer, others find the reverse, and none of them held the developer and the scene the same.
07 · Recipes
Tri-X recipes
A “Tri-X recipe” for a Fujifilm camera is a black and white film simulation with settings tuned by eye until its JPEGs resemble Tri-X prints or scans. Some are close in feel; none comes from the film’s data, since a Fujifilm camera does not run film curves. More in Fujifilm recipes.
In Lightroom or any editor the levers are the ones above. Convert to black and white with blue weighted up and green down (a yellow filter brings blue back down), set one curve with a long, slow toe and no shoulder, make it a grade harder than looks natural, and add a visible grain. For the pushed look, harder again, with the deepest shadows black. How to make photos look like film has the steps.
08 · Clack
Tri-X 400 on an Android phone: Street 400
Clack is a film camera app for Android. One of its eight films is Street 400 (based on Kodak Tri-X 400): Tri-X 400’s curve and spectral sensitivity, read off Kodak’s datasheet, printed on grade 3 paper with a fine grain. The look is in the finder as you frame and baked into the JPEG. A black and white film has no white balance, so its controls are the lens’s and the darkroom’s:
| Control | Steps | On Street 400 |
|---|---|---|
| Filter | None, Yellow, Orange, Red, Green | Wratten 8, 21, 25 and 58, through Tri-X’s own sensitivity; the meter makes up the factor |
| Polarizer | Off, Half, Full | Blue sky and water up to a stop darker, done by color, not by the angle to the sun |
| Bloom | Off, Faint, Soft, Strong | Lights bloom, as through mist ⅛, ¼ and ½ filters |
| Lens | Glass, Plastic | Plastic is a disposable camera’s one plastic lens, 32 mm at f/10: soft, dark corners and a veil in bright light |
| Contrast | Soft, Normal, Hard, Harder | Pulled one stop to pushed two in T-MAX developer. Harder is Kodak’s EI 1600 time; Hard and Soft are estimates, since Kodak gives no push 1 or pull |
| Grain | Fine, Normal, Coarse | The film’s own at Normal, coarser as the light falls |
Clack comes with one recipe on it, Contact Sheet: Tri-X as it comes, for the street in any light. Press 400, based on HP5 Plus, is Clack’s other black and white film. Clack sets the two apart as photographers tell them, not as the sheets do: Street 400 on grade 3 with a fine grain, Press 400 a grade softer with a coarse grain. That is a choice of taste, not a measurement.
- The film base
- On Android phones whose camera offers a contrast curve, Clack takes the frame flat, with the phone’s local tone mapping and color enhancement off, before the film. On other phones the films run on the phone’s own frame.
- Pushed, not rated
- Clack exposes for the meter. Hard and Harder develop the negative longer at that exposure, so they add a push’s contrast and grain without darkening the frame.
- Free or Pro
- For seven days of shooting every film is open. After that the free tier keeps one film of your choice, which can be Street 400; Clack Pro has them all.
A model of the film’s data on a phone’s photo, not film. Tested mostly on the CMF Phone 2 Pro.
AndroidGet free access to the closed beta. More about Clack
Questions
- Is Kodak Tri-X 400 still made?
- Yes. Kodak Alaris’s datasheet (F-4017, October 2021) lists Tri-X 400 in 135 and 120, and in a single-use camera of 27 exposures. Tri-X 320, a different emulsion, is made in sheets only.
- Is Tri-X 400 fine grain?
- Kodak calls it fine: a diffuse rms granularity of 17, measured in HC-110; Kodak says a push increases graininess. Since 2007 the film is finer-grained than the Tri-X of the decades before. More in what is film grain.
- Can you shoot Tri-X at 1600 or 3200?
- Yes, with push processing. Kodak gives times for EI 1600 (two stops, 8¾ minutes in T-MAX developer, 9½ in D-76, small tank at 20 °C) and EI 3200 (three stops, 11 minutes in D-76). Kodak expects more contrast and grain and less shadow detail at each. At EI 800 Kodak says to develop normally.
- What is the difference between Tri-X and HP5 Plus?
- Less than their reputations. At each maker’s normal time the two have one curve shape, a long toe and then a straight line; HP5 Plus is a touch harder, contrast index 0.59 against 0.56. HP5 Plus renders greens lighter and reds and blues darker. Photographers often call Tri-X the punchier film; that comes from development, printing and scanning more than from the sheets.
- What filter should I use with Tri-X?
- For skies, a yellow No. 8 (factor 2, one stop) darkens blue a little so clouds stand out; an orange No. 21 more; a red No. 25 (factor 8, three stops) turns blue sky dark and lightens skin. A green No. 58 lightens foliage. With no filter, Tri-X prints blue sky lighter than the eye sees it.
- What is the difference between Tri-X 400 and Tri-X 320?
- Tri-X 320 (320TXP) is a slower sheet film on a thick ESTAR base, made in Kodak’s words for “excellent tone gradation and brilliant highlights”, for low-flare studio and flash light. Tri-X 400 (400TX) is the 35 mm and 120 film, and the one Kodak recommends for push processing.
- Is Clack’s Street 400 the same as Tri-X 400?
- No. It is a model of Tri-X 400’s published data (its curve, its spectral sensitivity, Kodak’s push and Wratten filter curves) printed on grade 3 paper, run on the phone’s photo, so the lens and sensor are the phone’s. Clack is not affiliated with Kodak.
Sources
- Kodak, Professional Tri-X 320 and 400 technical data F-4017 (October 2021)
- Wikipedia, Kodak Tri-X
- Kodak, WRATTEN 2 filters (transmittance data)
- HARMAN technology, Ilford HP5 Plus technical information (2018; archived)
- RI Film Lab, Kodak Tri-X vs Ilford HP5
- Analogue Wonderland, Kodak Tri-X vs Ilford HP5
- spektrafilm: digitized curves of Kodak’s Portra Endura paper, the paper Clack prints black and white on (CC BY-SA 4.0)
Kodak, Tri-X, T-MAX, Ektachrome, XTOL, D-76, HC-110, Wratten and Estar are Kodak’s or Kodak Alaris’s; Ilford and HP5 are HARMAN technology’s; Fujifilm is Fujifilm’s. Clack is not affiliated with any of them.