Divided D-23 and Ilford films zone system times and testing -- looking for advice

[adelorenzo]

I've been experimenting with Divided D-23 as a developer, using Formula #2 from the Darkroom Cookbook. I've also referred to Sandy King's excellent article. I've gotten good results with HP5+ but seem to be having trouble with FP4+, so I thought I'd see if anyone here had an opinion or some experience to share.

Here are the particulars of my methods:

• Darkroom Cookbook modified D-23 developer (5g metol, 100g sodium sulfite per litre) (A)
• Sodium carbonate 9g/L for second bath (B) -- I am using this because I didn't have Kodalk or Borax handy, this is supposed to give the most grain, contrast and film speed of the three choices.
• Rotary agitation at 20 C in Jobo tanks or Expert drums
• Both A and B solutions used one shot
• Reading my negatives with a calibrated densitometer

My first tests were done using HP5+ 120 roll film. I got to an EI of 250, developing for 4.5 minutes in both A and B solutions. The negatives look great in terms of contrast, shadows and highlight detail. I've been shooting with this for a few weeks and it's been consistently good.

Next I've been trying to dial in FP4+ in sheet sizes (4x5 and 8x10). At an EI of 125, using the same development as above, I get the correct shadow/Zone 1 readings but I don't seem to be getting what I expect in the highlights, it's more like an N-1 development. Looking at a real-world negative it definitely doesn't have the highlight density that my HP5+ roll film negatives do or my FP4+ sheet film negatives that I have developed in HC-110.

I was expecting that FP4+ would require the same or even less development time than HP5+. I'm confused by the fact that I am getting flat highlights. I'm still working on testing but in the meantime, if anyone has theories on why this is the case I would be glad to hear them.

 

[adelorenzo]

Thanks Michael, that thread is really helpful and I appreciate all the analysis you put into it.

I will definitely try longer times in bath A to see how that helps. For some reason, I expected that my times for FP4+ would be shorter than my times for HP5+.

 

[adelorenzo]

I'm going to add some information into the thread as I think it might be helpful. From Ron Mowrey on photo.net:

Myths in B&W photography #4: Divided developers are great / ok / no good
All of the above are possible.

Consider this.... Each film has a different amount of silver halide and a different amount of gelatin. Not all films are hardened the same. So, the content and swell varies from film to film. A divided developer functions by absorbing enough of part A to do the job of development when the soaked and swollen film is placed into part B.

Here is where the problem comes in. Due to the different amounts of A that different films absorb, the extent to which B can do its job varies in proportion. Let us imagine a thick film that swells a lot and a thin hard film that does not. If you place both of them into part A, the thin hard film may be actually starved for solution, but the thick film may have an excess. In part B, the thin hard film will probably be underdeveloped.

Thefefore, the divided developer and the process conditions (time in A and time in B) must be adjusted for each film or the optimum results will not be obtained. Customizing a divided developer is a very painstaking job and can become quite expensive. The results are very good when optimized, but can be very poor if not optimized. The bottom line is that you should not use the same conditions for every type of film!

 

[adelorenzo]

I have a load of 8x10 FP4+ sheets washing right now. I processed them at 6+4 minutes. To the eye they look a lot better, obviously I haven't measured the density yet.

I wonder if the 'swell' factor comes into play here. I'm shooting HP5+ in rolls and FP4+ in sheets so there may be a difference in the bases.

 

[grahamp]

The amount of Bath A carry over may vary a lot between 120 spirals and sheet film tanks. This can affect the activity in Bath B, but it is hard to quantify the diffusion effect. I'd compare roll to roll, and sheet to sheet if possible.

By and large, Bath A will build density evenly. Bath B adds contrast and adds some density, but the small amount of developing agent means it will not keep adding density forever. I looked at the Bath A versus the combined effect with the standard Thornton formula and it was apparent that overall density comes from Bath A development, and contrast+density from Bath B.

I note the original post was using HP5 down-rated 2/3 stop, but trying FP4 at box speed. That's another possible variable.