KodakKodachrome 25

Kodak Kodachrome 25 was an ISO 25 color slide film for daylight, processed only in Kodak’s K-14 process. It was the slowest and finest-grained of the three Kodachromes sold from 1974, and the first to go: it was discontinued in 2002, and Kodak retired the whole line in 2009 [3] [1]. Its look survives in existing slides and in imitations such as the Grain Archive style, not on film.

Look and color

Kodak wrote only that the film “reproduces subtle color naturally” [1]. The rest comes from photographers, and most writing about “Kodachrome” concerns the 64 or the whole line, so the accounts specific to the 25 are few:

• Subtle rather than punchy. Fuji X Weekly describes the 25 as having “slightly more subtle tones and finer detail” than the 64, which it calls “more contrasty, vibrant and a hair warmer” [5].
• Accurate color. Simon Foale, scanning his own slides, found colors on both films “generally pretty accurate”, and better on the 25 [4]. He saw “a bit of a cyan cast” in Kodachrome 64 skies, “especially compared to KM25 and Velvia” [4].
• Richer and sharper on average. In his words, the 25 images “generally looked better, on average”, being “a bit richer, sharper, and less grainy” [4].
• Reds, greens and skin. We found no source specific to the 25 on these. Accounts of warm, rich Kodachrome reds are about the 64 or the line as a whole; see the Kodachrome 64 page.

Reviewers of the 64 more often mention contrast and warmth; if these accounts are right, the 25 is the quieter of the two.

Tonality

• Curve. On the datasheet’s characteristic curves, D-min sits near 0.2 and D-max is not reached: the red, green and blue curves are still rising at about 3.7, 3.5 and 3.4 [1]. The three curves look close to those of the 64, with the same gradual descent and no hard wall (our reading of the graph).
• Contrast. Lower than the 64 in the two accounts above [4] [5].
• No push. Kodak did not recommend push processing for Kodachrome 25 or 64 [1].
• Long exposures: no correction from 1/10,000 to 1/10 s, +½ stop at 1 s, and 10 s not recommended [1].
• Tungsten light: EI 6 with an 80A filter at 3200 K, EI 8 with an 80B filter at 3400 K [1].
• Slow speed. Foale recalls shooting a sunset at f/2.8 “due to the low light level” [4], and Fuji X Weekly says the low ISO made the film “difficult to use” [5].

Grain and sharpness

• Kodak describes the 25 and the 64 as “extremely sharp” with “extremely fine grain” [1]. The figures come from different decades and manufacturers: treat them as roughly comparable only.
• The datasheet gives modulation transfer curves but no resolving power. The 25’s response reads about 100 % up to around 30 cycles/mm, higher than the 64’s (our reading of the graphs) [1].
• Grain: a contradiction. Foale writes of the “near absence of grain” [4]. John Shaw, at 100 % on a scan of a 1982 slide, wrote: “it is a sharp film but look at the grain” [6]. Fuji X Weekly calls it “probably the sharpest color film ever made” [5]. Scanner, resolution and magnification explain much of the difference.

Spectral sensitivity

The datasheet gives Kodachrome 25 its own spectral sensitivity graph. The green-sensitive layer is nearly flat from about 550 to 575 nm, with a slight dip between two small peaks, and the red-sensitive layer peaks near 650 nm at a lower level than on the 64 [1]. Whether these differences show in the rendering is not documented, and the Grain Archive style is not computed from the curves [11].

Names, status and history

• 1974. Kodachrome 25 and Kodachrome 64 replaced Kodachrome II and Kodachrome-X, with the change to the K-14 process [3].
• Product codes. The Professional 135 version was coded PKM in Kodak’s datasheets, next to PKR (64) and PKL (200) [1]. In Super 8 the film was sold as Kodachrome 25 from 1975 to 2002, according to a Super 8 database [7].
• 2002 or 2003: end of Kodachrome 25. Wikipedia says it was discontinued in 2002 [3]. Kodak’s August 2003 datasheet states that Professional Kodachrome 25 / PKM “has been discontinued” and suggests Kodachrome 64 as the replacement [2]. The exact date of the last production is not given in these sources.
• A source conflict. The June 2009 datasheet still describes Kodachrome 25 beside the 64 and 200, under a notice that the Kodachrome film has been discontinued and will be sold while supplies last [1]. It is the same E-55 document for the three films, not proof that the 25 was still made.
• 2009 and after. Kodak retired the line in 2009, with no exact replacement; it suggested Ektar 100 and Ektachrome E100G [1]. The last lab, Dwayne’s Photo in Kansas, was due to stop its Kodachrome machine on December 30, 2010 [8]; Wikipedia reports January 18, 2011 for the last rolls [3]. Kodachrome can no longer be developed in color.