IlfordFP4 Plus

Ilford FP4 Plus is an ISO 125 black-and-white negative film with a traditional cubic-grain emulsion, made by Harman Technology in England and developed in standard black-and-white chemistry [1] [5]. Ilford sells it as fine-grained, of medium contrast and with wide exposure latitude [1] [4]. The FP line dates from 1935; FP4 arrived in 1968 and FP4 Plus in 1990 [10] [11].

Look and color

FP4 Plus turns colors into grays according to its own spectral sensitivity, not the eye’s:

• Blue renders lighter, skin and reds darker. Converting our test RAW files with the FP4 Plus curve instead of plain luminance made a sky 3.6 L* lighter, skin 4.6 L* darker and a pink shirt 1.8 L* darker [16].
• Less blue than HP5 Plus. On Ilford’s charts, which use the same graduations, FP4 Plus is less sensitive than HP5 Plus in the violet and blue (0.39 against 0.68 at 400 nm) and peaks further toward the red, near 600 nm instead of 570 nm [1] [12]. In our conversion, skin darkens less than with HP5 Plus: −4.6 against −5.7 L* [16].
• Filters. The still-film datasheet refers to the filter maker’s factors [1]. The fact sheet of the motion-picture version gives daylight factors of 2 for a No. 8 yellow, 3 for a No. 21 orange and 6 for a No. 25 red [2].
• Reviews talk about texture rather than color: a “classic” look [9], “a more classic and textured look” than tabular-grain films [10].

Tonality

• Curve. On the datasheet curve (Ilfotec HC 1+31, 8 min), base plus fog sits near 0.1 and the toe spans about one log unit. The straight section rises at a gradient of about 0.8, then a clear shoulder starts near 3.3 on the relative log exposure axis and flattens around a density of 1.9 (our reading of the graph) [1]. HP5 Plus, in the same developer at its own recommended time, rises at about 0.65 with no shoulder up to a density of about 2.1 [12]. FP4 Plus has firmer midtones and more compressed highlights.
• Contrast. Ilford calls it “medium” [4], Film Processing “moderate” [7]. The Darkroom praises its “smooth tonal transitions” [6] and Emulsive its “long tonality” [5].
• The reviews disagree on how punchy it is.
  • Shoot It With Film found the contrast “incredible”, “with deep blacks and plenty of details in the highlights” [9]; Blue Moon Camera describes “dramatic and deep shadows” [10].
  • Analog.cafe found that its portrait scans “lacked tone variation in the mid-greys” [8].
  • Emulsive explains part of the gap: cool, dilute developer with moderate agitation gives fine grain and shadow detail, warm and less dilute developer gives “fat grain and high contrast” [5].
• Latitude. Ilford promises usable results from 2 stops under to 6 stops over. Best results come at EI 125, and good ones from EI 50 to 200 with adjusted development [1].
• Long exposures: no correction from 1/10,000 to ½ s. Beyond that, Ilford’s graph follows adjusted time = metered time^1.26 [1].

Grain and sharpness

• The still-film datasheet gives no RMS figure and calls the grain “exceptionally fine” [1]. The value of 10 comes from the fact sheet of FP4 Plus negative motion picture film, developed in Kodak D-96 for 5½ min at 24 °C [2]. Values measured in different developers are only roughly comparable.
• Reviews: “fine yet still noticeable grain”, unlike “ultra-smooth” Delta 100 or T-Max 100 [6]; “cubic grain” [5]; “very soft and pleasant” [9]. Film Processing finds it finer than HP5 Plus, which has “more pronounced grain” [7].
• Sharpness: Ilford publishes no resolving power [1]. Emulsive praises “outstanding sharpness and high acutance” [5] and Analog.cafe calls it “very sharp” [8], while Shoot It With Film finds it less sharp than Delta 100 [9].

Spectral sensitivity

Ilford publishes a wedge spectrogram made under 2850 K tungsten light. The curve climbs from about 365 nm, levels off between 465 and 485 nm, dips slightly near 505 nm, peaks around 600 to 610 nm and falls steeply past 630 nm [1]; the 2001 edition prints the same curve [3]. Tungsten light is much richer in red than in blue, which lifts the right side of the chart. Once that is corrected, blue skies still render lighter and skin darker than in a luminance conversion [16].

Names, status and history

• 1935 to 1990. FP stood for Fine grain Panchromatic and dates from 1935. Wikipedia lists FP2 (1939) and FP3 (1942) before FP4 in 1968 and FP4 Plus in 1990 [11] [10].
• Maker. The datasheet is published by Harman Technology, in Mobberley, England [1].
• Formats. On September 29, 2026, Ilford’s product page listed FP4 Plus in 35 mm, 120 and sheet film [4]. The datasheet details 35 mm cassettes of 24 and 36 exposures, 17 m and 30.5 m bulk lengths, 120 rolls and sheets [1]. The 2001 fact sheet also listed 220 rolls [3].
• Motion-picture version. Ilford has also published a fact sheet for FP4 Plus negative motion picture film in 35 mm and 16 mm, rated EI 125 in daylight and EI 100 under 3200 K tungsten light [2].
• Datasheet. The current still-film datasheet is dated November 2018 [1].