Gast
Hello Sabine,
I’ve tested the FX-39 with APX100, Delta100 and Acros. The most important finding: the development times given are only rough guidelines. Regardless of the instructions on the package leaflet, the effective speed is slightly lower than the film’s nominal speed (see Mirko’s comments on the ADX developer). With a bit of luck, you can achieve 64 ASA with the Acros, and 80 ASA with the other two. These speeds are also achieved with many other developers for these films. In other words, I could not detect an increase in speed as advertised on the package insert.
I have found that a characteristic feature of this developer is that, at the agitation rate recommended by the manufacturer, the characteristic curve for all three films has an S-shaped profile and thus deviates from the ideal curve (extended mid-section with a straight curve). This results in the grey tones in the mid-range being rendered somewhat harder, thereby creating an apparent increase in sharpness. The trade-off is a reduced differentiation of grey tones in the shadows and highlights.
Whether this is an advantage depends on the subject.
Best regards,
Otto Beyer!
