Two Ilford films that break the rules: XP2 Super and SFX 200

Most of Ilford's black-and-white range behaves the way black-and-white film is supposed to. Two films do not, and their data sheets explain how.

XP2 Super: black and white made of dye

XP2 Super is a chromogenic film: the dyes that make up its image are formed during development, rather than being in the film beforehand or added later ¹. It is processed in the standard C-41 colour process, which is how its ISO 400 rating was measured ¹. That has practical consequences that the sheet spells out. Labs should set replenishment as if it were an ISO 200 colour negative film, however it was exposed ¹. Push processing is not recommended, because unlike conventional ISO 400 films it gives no practical increase in speed; Ilford's alternative is to expose it at EI 800 and give it standard processing ¹. And despite the colour chemistry, the negatives print on ordinary black-and-white paper in the same way as conventional black-and-white negatives ¹. In 35mm it is coated on a 0.125 mm acetate base, the same thickness Ilford uses for HP5 Plus ^1,4. Its long-exposure factor in Ilford's reciprocity formula is 1.31 ³.

SFX 200: reaching into the red

SFX 200 has extended red sensitivity, up to about 740 nanometres, beyond the range of an ordinary panchromatic film ². Ilford designed it to be used with a red filter for effect: with a very deep red filter, skies can be rendered almost black and most green vegetation almost white ². It is still fully panchromatic, so without a filter it gives ordinary pictorial contrast ². Its ISO 200 rating was measured in ID-11 ², and the sheet gives a table of filter factors from light yellow to deep red, warning that with very dark filters exposures can be long enough to need a tripod ². Those long exposures meet the steepest reciprocity factor in Ilford's range, 1.43 ³: a metered 30 seconds becomes about 130.

One small detail from the sheet: SFX in 120 is edge numbered 1 to 19 ².

Which to try

If you want black and white from a high-street C-41 lab, or a film that forgives an extra stop of exposure, XP2 Super is designed for that. If you want a dark sky and pale trees without infrared film's handling, SFX 200 and a deep red filter are the route Ilford designed.