Rollei RPX 25 in 120 is the same ISO 25 black and white emulsion as the 135 version, on a medium format spool. The maker states 12 exposures; on a 6×6 camera that is the standard roll.
How the picture looks
The high resolution and very fine grain the maker states show even more plainly across a 6×6 frame than on 35 mm: a large print from this barely shows grain at all. The curve is S-shaped, the image contrasty, the shadows thin on detail.
The infrared effect
Sensitisation is superpanchromatic. An infrared effect is possible, but only with a filter blocking visible light up to about 715 nm — the maker names the Heliopan RG 715.
What to shoot on it
A tripod and daylight. Landscape, architecture, studio still life — anything where ISO 25 is no obstacle and resolution is the point.
About the base
The emulsion sits on a PET base with a special coating for even transport. That base is clearer than acetate, so change rolls in shade rather than sunlight and wind the exposed roll tight.
Processing and scanning
Ordinary black and white processing, times from the maker’s table for your developer. If the contrast looks too high, give more exposure and cut development.
