The high level of Sodium Chloride used as a restrainer & silver solvent in Perceptol & Microdold-X greatly reduces the effective film speed.
Ilford claimed a speed increase for Hyfin, but the 1 stop is more likely with FP3 or FP4, I'd have to agree that it might not be as much with Pan-F. The solvent effect of Sulphite in D76/ID-11 does drop the effective speed, so a developer like Adox Borax MQ with less Sulphite give half a stop more speed.
With such a low level of Metol these Beutler type developers are compensation so shouldn't be over contrasty they were designed to be used with films like Pan-F & FP-3/4, and Kodak tailored its HDD for Pan-X etc. The low level of Sulphite allows greater effective film speed, remember we use high sulphite developers like ID-11/D76 as our benchmark.
Last edited by Ian Grant; 08-02-2009 at 08:37 AM. Click to view previous post history.
Reason: add clarity