FX-39 vs Acutol on Neopan 400

Over the last week I have been testing Paterson FX-39 angainst
Paterson Acutol on Fuji Neopan 400. Bear in mind that the results are
based on two tests. The results were consistent, which is always a
hopeful sign when performing tests. Getting different results on
multiple tests is always discouraging.

Now, for the test results.

First of all, it was necessary to dilute FX-39 33% more than Acutol to
get similar results. I diluted Acutol at 1+14 and FX-39 at 1+19 and
developed the films for 8 minutes at 20C/68F. This gave almost
identical contrast and density.

This is quite at odds with Paterson's recommendations, which call for
a dilution of 1+9 for both, and a development time of 8,5 minutes for
Acutol and 10 minutes for FX-39. The latter time in particular seems
grossly erroneous. Using FX-39 at 1+9 dilution and developing this
film for 10 minutes would yield horribly overdeveloped negatives.

According to my observations, it seems that Acutol is a little
softer-working, and provides more shadow detail (more density) and
highlight detail (less density). I would estimate that Acutol provides
about 1/6 th of a stop more speed than FX-39 on this film.

FX-39 seems to offer ever so slightly finer grain and better
sharpness, but this can be seen only at 13 diameters or better. I
would estimate the difference at less than 5%. This would seem to make
sense, as getting more speed usually involves a trade-off in other
areas. But in the case with Acutol, there is overall more latitude on
both ends of the scale: more shadow detail and more highlight detail.
This can be be very useful in contrasty situations.

I'll post some of the test results today, but the subtleties may not
show up on scans.