Rollei RPX 25

RPX 25 exists for situations where most film shooters would reach for a tripod and a slower shutter. At ISO 25 you are working deliberately by definition. The emulsion is repackaged Agfa Aviphot Pan 80 from Agfa-Gevaert in Belgium, the same aerial-survey stock that sits behind Rollei Retro 80S, rerated by Maco to ISO 25, and it shows the lineage: tight cubic grain, good separation in the upper zones, and a straight enough curve that Zone System workers can trust their placement.

The practical use case is 35mm shooters who want to make large prints without apologizing for grain. Shoot a roll of RPX 25 at box speed in good afternoon light, process normally in D-76 or Rodinal 1:100, and you get a negative with genuine resolution headroom. Enlarging to 16x20 from 35mm is usually where traditional grain becomes a creative choice rather than a technical limitation; with RPX 25 it is closer to a technical asset.

In 4x5 the film rewards contact printing and fine-art enlargement work. Still life photographers and architectural shooters who care about zone VII and VIII separation find it useful because the highlights hold information a stop or two past where faster films start to compress.

The reciprocity exponent is 1.31, which matters more at ISO 25 than it might seem at first. A one-second reading at this speed can happen in ordinary indoor light, not just long nighttime exposures. Zone Light Meter starts applying the correction automatically once you cross the one-second threshold, which saves you the mental arithmetic at the moment you are also juggling composition and depth of field.

One practical note: RPX 25 in 35mm has tight tolerances on exposure. A stop of overexposure is less forgettable here than with HP5+. Rate it accurately, meter carefully, and it rewards the discipline.