KodakPlus-X 125

Kodak Plus-X 125 is a medium-speed panchromatic black-and-white negative film with extremely fine grain, which Kodak pitched for general-purpose outdoor and studio work [1]. It descends from a motion-picture stock introduced in 1938 [2]. Kodak’s still version was reported discontinued in 2011, so it now survives only as expired film [2] [3].

Look and color

The datasheet describes the look in general terms: “rich tonality maintained with overexposure and underexposure” and “excellent sharpness” [1]. The reviews we read describe it in more detail:

• A “rich palette of middle grays” rather than punch, and a “creamy, dreamy quality” in even light, less at ease in harsh sun [6].
• “Perhaps like a finer grain Ilford FP4 Plus with a creamer look”, with lower contrast than T-Max 100. That review used expired film developed in Xtol [4].
• “Deep and mesmerizing” blacks, clean mids and highlights that are “not at all harsh” (Cockroft, film exposed at EI 80) [5].
• A long-time user calls it the “nicest combination of fine grain, beautiful tonality and ease of use” [3], but says FP4 Plus, the usual replacement, is “not quite as nice”.

None of the reviews we read describes how it turns colors into grays. Kodak’s daylight filter factors, if you want to darken skies, are ×2 for a No. 8 yellow, ×2.5 for a No. 15 deep yellow, ×6 for a No. 25 red and ×8 for a No. 58 green [1]. The Grain Archive style relies on the spectral curve alone: with it, a sky renders 5.5 L* lighter, skin 1.5 L* darker and a pink T-shirt 2.2 L* darker than in the base render [9].

Tonality

• Curve. On the datasheet’s characteristic curves (D-76, small tank, 20 °C), the toe is long and gentle. The gradient reads about 0.75 in the straight part for 7 minutes, and the curve is still rising at log H +0.6 (density about 2.2): there is no marked shoulder. This is our reading of the graph [1].
• Development sets the contrast. The datasheet plots 5, 7 and 11 minutes and a contrast-index chart for several developers [1]. One reviewer, using Ilfotec LC29 1+19 for 6 minutes, found “good latitude with a moderate amount of contrast” [2].
• Latitude. Kodak lists “wide exposure latitude” [1]:
  • one stop under (EI 250) with normal development gives prints with a slight loss of shadow detail;
  • two stops (EI 500) need a longer development, with more contrast and grain; EI 1000 is offered with a 3-stop push in XTOL.
• Long exposures. No correction from 1/100 to 1/10 s. From 1 s, add 1 to 3 stops and cut development by 10 to 30 % [1].
• Handling. One reviewer’s roll “curled something awful” after development and stayed under books for two days before scanning [5].

Grain and sharpness

• Kodak calls an RMS of 10 “extremely fine” [1]. RMS values measured in different developers are only roughly comparable. Ilford publishes no RMS for the still FP4 Plus, so the equal figure is indicative.
• Reviewers: “smooth, fine grain without appearing plastic” [5]; “impressed by the latitude and fine grain”, on expired film [4].
• Sharpness: Kodak lists “very high sharpness” and “high resolving power”. The table gives a resolving power of 125 lines per millimeter at a test-object contrast of 1000:1 and 50 at 1.6:1 [1].

Spectral sensitivity

On an equal-energy basis, the film is most sensitive in the violet, with a maximum at 408 nm, then declines to a shallow dip near 515 nm, holds a modest plateau from 550 to 625 nm and cuts off rapidly between 640 and 660 nm [1]. In practice, blue and violet render lighter than the eye sees them, and reds render darker than in a luminance conversion [9].

Names, status and history

• 1938. Plus-X began as a Kodak motion-picture film in 1938, and was later sold for still cameras in several formats [2]. Its still speed reportedly went from 50 ASA to 80 in the 1950s, then 160 in 1960, before settling at ISO 125 for nearly fifty years [2].
• 125PX. Around 2006 the film was reformulated and given the code 125PX, with development times similar to its predecessor but 15 to 30 seconds different [2]. The 2007 datasheet covers both names, “Plus-X 125 Film / 125PX”, and notes that black-and-white film production was moving to a new coating facility, so processing times could differ slightly [1].
• 2010 and 2011. The motion-picture stock ended in 2010, and the still film was reported discontinued in 2011 [2] [3]. Reviewers call it Kodak’s last slow, traditional-grain black-and-white stock [5]. We found no Kodak announcement, only these secondary sources, so the exact date is unconfirmed.
• Formats. The 2007 datasheet lists 135, 35 mm long rolls, 120 and 220 [1].
• Datasheet. The most recent one we found is F-4018 from May 2007. It is hosted by 125px, not by Kodak [1].

Also sold as

• Kodak Professional Plus-X 125 / 125PX (the datasheet title; 125PX is Kodak's product code) (confirmed) [1]