Mark C
Well-known
This came out of some email discussion with Calzone about shooting in a particular low light venue I go to. I had used 2x Diafine a couple years ago there, and sometimes Acufine. Cal mentioned liking Diafine with extended times more than running the film through the Diafine twice. In theory, and according to the directions, this should not work, but I decided to try for myself while I was also freshening up my replenished Acufine and would have a comparison to that.
I had most of a roll of Kentmere 400 I wanted to finish up in a camera, so shot about 24 identical frames of a high contrast scene at about EI 1600, then did clip tests. Cal mentioned 7 minutes in A / 4 minutes in B. I ended up my first run in my 2 year old Diafine with about 4/4 (A/B) and 7.5/5 at about 73 degrees. The 4 minute clip had the weak results I'm used to seeing from Diafine on modern films, but was surprised to see a much better developed exposure on the 7.5 minute clip.
I mixed and tested fresh Diafine last night make sure this wasn't the result of my old developer. The 4 minute clip might have been a tiny bit better with the fresh developer, but the overall results were similar and the longer time looks identical to me (these are still clips from the same roll). I also did a much extended time of about 16/5 just to test the limits and found almost no change, but just a very slight increase in density.
Those are my test results. My HP5 and TriX results are very similar. My conclusions might be different than yours. In theory, the longer times should make almost no difference. I used Diafine a bit many years ago and did not get the weak results I see now when used at the recommended times. I've assumed this is the difference in modern film, possibly thinner emulsion or more hardening. With a direct comparison including extended time my thought is that modern films may or may not do quite as well in Diafine, but that mostly they just need longer times. Of course, if you are happy with the box times there is no reason at all to change, unless you want more density and slightly more contrast.
Sorry for the long post, but lots of ground to cover. I hope this is of interest here. Thanks to Cal for the helpful input.
I had most of a roll of Kentmere 400 I wanted to finish up in a camera, so shot about 24 identical frames of a high contrast scene at about EI 1600, then did clip tests. Cal mentioned 7 minutes in A / 4 minutes in B. I ended up my first run in my 2 year old Diafine with about 4/4 (A/B) and 7.5/5 at about 73 degrees. The 4 minute clip had the weak results I'm used to seeing from Diafine on modern films, but was surprised to see a much better developed exposure on the 7.5 minute clip.
I mixed and tested fresh Diafine last night make sure this wasn't the result of my old developer. The 4 minute clip might have been a tiny bit better with the fresh developer, but the overall results were similar and the longer time looks identical to me (these are still clips from the same roll). I also did a much extended time of about 16/5 just to test the limits and found almost no change, but just a very slight increase in density.
Those are my test results. My HP5 and TriX results are very similar. My conclusions might be different than yours. In theory, the longer times should make almost no difference. I used Diafine a bit many years ago and did not get the weak results I see now when used at the recommended times. I've assumed this is the difference in modern film, possibly thinner emulsion or more hardening. With a direct comparison including extended time my thought is that modern films may or may not do quite as well in Diafine, but that mostly they just need longer times. Of course, if you are happy with the box times there is no reason at all to change, unless you want more density and slightly more contrast.
Sorry for the long post, but lots of ground to cover. I hope this is of interest here. Thanks to Cal for the helpful input.