psmithp
Member
They give a development time for FP4+ EI 50 in Perceptol in the Perceptol datasheet. But at the same time they also provide times for higher EI's. I haven't been able to locate anything from Ilford that the 'real' speed of the film would be limited to 50. I doubt they'd say something like this.
If I remember right, they said so in the 1970s - then they only gave a time for 50ASA (as it was at the time). But it was FP4, not FP4+.