Divided developer pros and cons

[swmcl]

Hi,

I am slowly gaining ground in my understandings and now I visit the divided developer.

There are a good number of benefits to the divided developer some of which I see are:

1. Less developer used is less down the drain into the environment
2. Many films can be put through the same batch of developer
3. Development times are not as critical
4. Development temperatures are not as critical - good for hotter climates!
5. No blown highlights
6. Almost impossible to underdevelop to the point of getting nothing - good for rescuing a badly exposed negatives I guess
7. You can develop all sorts of film in the same developer at the same time ?!?!
8. Its relatively cheap ...

The cons may include:

1. It may not bring out the best of any film - more like a generic so-so performance as such ...
2. Not good on low contrast images - too flat

My question is ...

If there is a contrast index that is suited to condenser enlargers and another for diffusion enlargers, wouldn't the contrast index from a divided developer be too low for a good printing outcome? Perhaps my question more relates to the printing side of things in essence. How does printing of flatter than normal negatives work out in practice? I don't see too many saying they like to print from flat negatives too much but I get the impression that one should develop their negative according to the intended printing method!

Thoughts?

[ic-racer]

How does printing of flatter than normal negatives work out in practice?

What is "normal?"
In general, modern negatives have six to eight tenths the contrast of the original scene. So they usually are always flatter than the original. In the 1970s, high quality multigrade paper by Dupont and others revolutionized darkroom printing, making fine-tuning of negative development less important.

[Leigh]

I've used Diafine for many years, and have been very pleased with the results.
Note that I only shoot slower films, 100ASA or less.

It's the only developer I use in trays, due to its wide tolerance of temperature variations.

The major difference between divided types and regular singles is the divided ones do not like pre-soak.
Divided developers commonly work by soaking part A into the dry emulsion, then letting part B act on it.

Several grades of paper are designed for printing negs with lower contrast ranges, but only one for higher.

- Leigh

[jbenedict]

I have used divided D-23. "Textbook" D-23 is metol plus sodium sulfite. Divided D-23 puts the metol in Part A and the sulfite in Part B. There are some variations on the theme and are explained here:

http://unblinkingeye.com/Articles/DD-23/dd-23.html

When I taught photography to HS kids, my biggest problem was that they underexposed most everything no matter what they were told to do. I found it easier to do all of the film developing myself 12 rolls at a time in a Jobo and divided D-23 worked better than other things I tried because of the compensating effect.

Jeff

[Leigh]

I found it easier to do all of the film developing myself 12 rolls at a time in a Jobo and divided D-23 worked better than other things I tried because of the compensating effect.

That's an interesting comment.

Developer "compensation" works by depleting the developing agent in areas of high density.
That effect requires very minimal agitation, so no fresh developing agent is introduced in the area.

That cannot be achieved in any way when using a rotary processor.

- Leigh

[jbenedict]

That's an interesting comment.

Developer "compensation" works by depleting the developing agent in areas of high density.
That effect requires very minimal agitation, so no fresh developing agent is introduced in the area.

That cannot be achieved in any way when using a rotary processor.

- Leigh

The effect happens by introducing the accelerator in the Part B. The film absorbs the amount of Part A it needs depending on density and, after it is drained of Part A, the Part B accelerates and causes the action. The areas which have absorbed less Part A are exhausted faster than the ones which absorbed more Part A. See the link I provided above for a full explanation.

I used the Divided D-23 formula with the metol and sulfate in Part A and borax in Part B. It did produce the compensating effect and worked well.

[Leigh]

The film absorbs the amount of Part A it needs depending on density...

Can you explain how that happens?

There is no discernable difference between an exposed halide crystal and an unexposed one, and
certainly not among various levels of exposure.

So how does a component of part A concentrate itself in areas that will become more dense?

- Leigh

[Ed Bray]

I use divided Pyrocat HD/C on a Jobo CPP2 in an expert drum, I don't know how the divided developer works to give a compensating effect but it definitely does.

[jbenedict]

Can you explain how that happens?

There is no discernable difference between an exposed halide crystal and an unexposed one, and
certainly not among various levels of exposure.

So how does a component of part A concentrate itself in areas that will become more dense?

- Leigh

Read the article about three quarters down the page.

http://unblinkingeye.com/Articles/DD-23/dd-23.html

[sanking]

Here is another explanation of how compensation works with two-bath developers like Diafine and divided Pyrocat. With this method compensation takes place even with rotary development, and a pre-soak does not fundamentally change the nature of development, though it will impact the speed of imbibition. The language below is from an article on two-bath development I am working on and hope to complete this year. Most of the testing has already been done.

"The most common form of two-bath development consists of a first solution that contains only the reducer, and perhaps some sodium sulfite as a preservative, and a second bath that contains the alkali. The film is placed in Solution A, where it soaks up the reducer, but with no alkali present no image is formed. The film is then transferred to Solution B, which contains the alkali, accelerator, and the image is formed by the developing agents that have been imbibed by the gelatin layers of the film. The final contrast of the negative is limited by how much of the reducer the film was able to imbibe while soaking in the first bath. When the film is placed in Solution B the highlights develop first and then stop because the developer exhausts in this area, but the shadows continue to develop. If dilute solutions are used overdevelopment is impossible, even with negatives made in scenes of very great contrast."


Sandy