smieglitz said:
Donald,
I've taken a quick look at Sandy's article again (having read it in some detail months ago) and don't interpret the results in quite the same way. It would appear that FP4+ achieves a higher CI quicker than HP5+ in the pyrocat developer (for example reaching a CI of .95 instead of .85 at 20 minutes development time at same dilution) but my take on the data is that the HP5+ curve remains steeper at the extended times while the FP4+ curves are beginning to flatten several minutes before that final 20 minute data point. This suggests to me that if the development times were extended, the CI of HP5+ would catch up and perhaps even exceed that of FP4+ in the same developer. At a quick glance, the charts seem to indicate a difference in the initial rate of development rather than the absolute density range/CI achievable using these films and pyro developers. (I'll have to put the data on a single CI chart to see any trend more clearly.)
Perhaps Sandy could comment on this if he happens by.
I'll also check my notes and see if I can figure out the CI of my film test for VDB using HP5+ and HC110.
Thanks for the pointer to Sandy's data. Looks like I'll have to pick up some FP4+ and try it.
Joe
OK, here are my thoughts.
My original tests of HP5+, as seen in the article at unblinkingeye.com, were based on the *old* HP5+. I have done a lot of more recent testing with the newer HP5+, but have not as yet updated the article.
My most recent tests show that a CI of 0.95 is possible with the new HP5+ and Pyrocat 2:2:100 with about 22 minutes of development, rotary at 72ºF. However, the CI chart at that point shows the CI to still be on a straight line, i.e. climbing. That is, more time *might* result in a higher CI. But I only tested to 22 minutes, so can not say for sure. But I do allow the possibility at least that the film is capable of a higher CI than .95.
FP4+ is another bird. With the Pyrocat-HD 2:2:100 dilution a CI of about 1.15 is achieved with about 20-22 minutes of development. However, the CI appears to be leveling off at that point, so I don' t believe you can get much more contrast out of the film. But again, I don't know for *sure* because I did not test FP4+ in Pyrocat 2:2:100 for more than 22 minutes.
I don't like to punt on questions, but punting is better than providing inaccurate information. Or so I believe.
Sandy