FP is a cubic-grain[2] black-and-white film from Ilford Photo with a long history.[3] It originated as Fine grain Panchromatic roll film in 1935. Like its faster partner product, HP film, it has gone through a number of versions since then, with the latest being FP4 plus (FP4+ for short).

FP4 plus
MakerIlford Photo
Speed125/22°[1]
TypeB&W print
ProcessGelatin-silver
Format35mm, 120, sheets
ApplicationGeneral
Introduced1990
FP4
Speed125 ASA
TypeB&W
Introduced1968
Discontinued1990
Replaced byFP4 plus
FP3
Speed64 ASA, 125 ASA (1960)
TypeB&W
Introduced1942
Discontinued1968
Replaced byFP4
FP2
Speed40 ASA
TypeB&W
Introduced1939
Discontinued1942
Replaced byFP3
FP
Speed40 ASA
TypeB&W
Introduced1935
Discontinued1939
Replaced byFP2

The film is known for being versatile, with usable results even when underexposed two stops or overexposed six stops.[1] This is due to the fact that FP4 features a double layer emulsion. It combines a low sensitive fine grain layer and a highly sensitive layer with larger grains. This kind of film was already known in the 1920s and 1930s (e.g. Agfa Isopan F 17/10° DIN). Being perfect for the amateur's 6x9 roll film cameras these old types lacked sharpness in the 24 x 36 mm format due to the overall thickness of both layers. But the FP4 of 1968 combined an amateur-friendly double layer emulsion with the sharpness of a typical thin layer emulsion. This was possible because both layers together were only 7.5 μm thick.[4]

References

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  1. ^ a b "Archived copy" (PDF). Archived from the original (PDF) on 2016-06-04. Retrieved 2016-05-23.{{cite web}}: CS1 maint: archived copy as title (link)
  2. ^ "Film stock review: ILFORD FP4 PLUS in 35mm, 120 format and sheet film". Emulsive.org. 29 June 2015. Retrieved 22 March 2019.
  3. ^ "Ilford History and Chronology". Photomemorabilia.co.uk. Retrieved 2007-07-27.
  4. ^ Solf, Kurt Dieter (1975). Fotografie. Frankfurt am Main: Fischer. p. 28.
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