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swmcl
14-Apr-2014, 01:12
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
14-Apr-2014, 07:11
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
14-Apr-2014, 11:23
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
14-Apr-2014, 11:57
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
14-Apr-2014, 12:05
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
14-Apr-2014, 12:34
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
14-Apr-2014, 21:07
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
14-Apr-2014, 23:01
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
15-Apr-2014, 00:55
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
15-Apr-2014, 07:19
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

jbenedict
15-Apr-2014, 07:49
Cool! I like the idea of letting my film imbibe. I rather like to imbibe myself... ;) The kids had a hard time understanding how to make correct exposure. The use of the Divided D-23 caused many more of the pictures to come out usable.

Jim Noel
15-Apr-2014, 08:37
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.

Sulfate or sulfite?

Ed Bray
15-Apr-2014, 09:02
Sulfate or sulfite?

or sulphate or sulphite even

jbenedict
15-Apr-2014, 09:05
Sulfate or sulfite?

sulfite

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

Leigh
15-Apr-2014, 15:01
With this method compensation takes place even with rotary development...
When the film is placed in Solution B the highlights develop first and then stop because the developer exhausts in this area...
Sandy,

Please realize that those two statements are diametrically opposed.

There is no way the developer can exhaust in areas of high density unless it exhausts in the entire developer volume, since rotation continuously replaces fluid contacting the film surface with fresh developer.


... a pre-soak does not fundamentally change the nature of development, though it will impact the speed of imbibition.
Given that a pre-soak fills all available space in the emulsion, where does developer part A go?

If you're relying on diffusion, that is a very slow process.

- Leigh

richardman
15-Apr-2014, 15:05
I have been using Sandy's divided Pyrocat for almost 3 years now, on 35mm, 6x7, to 4x5. I don't know how it works, but it works, especially with my scanning-post work flow. Not sure how they will work if I print optically but the negs look good in all types of conditions.

sanking
15-Apr-2014, 15:25
When the film is placed in Solution B, with a developer like Diafine or Pyrocat-HD where there is absolutely no image formation in Solution A, development is virtually instantaneous as it exhausts from the highlights to the shadows in about 1/10 of a second. Development is about 98% finished before the film even has time to make one rotation in a Jobo. If you have ever made a DOP pt/pd print development in two-bath solutions like Diafine and Pyrocat-HD is similar, i.e. the image just appears as if by magic as soon as the film comes in contact with the alkaline solution.

As for the pre-soak, I have tested it extensively with several two-bath developers and many films. The pre-soak changes the imbibition rate of Solution A, depending on the thickness of the gelatin emulsion and the temperature, but it does not do anything to harm the film or development. The factors that determine how much reducer can be absorbed in Solution A are 1) the pre-soak, 2) fillm type, 3) developer concentration 4) agitation, 5) pH, and probably several other unknown factors.

Two-bath D23 and D76 act a bit different than Diafine and Pyrocat-HD in that the sulfite adds enough pH to activate slightly metol. With Diafine and Pyrocat-HD the pH requirements of the primary reducers is very high so nothing takes place in terms of image formation until the film hits Solution B.


Sandy

earlnash
15-Apr-2014, 19:43
Everyone has parts of it right, but not all of it. The exposed portions of the negative do not absorb any more or less of the developer (reducing agent) than do the underexposed portions. The "compensation" occurs when the film leaves the developer. There is a fixed amount of it soaked into every portion of the film. Then, in the second solution, which is an alkali activator, the heavily exposed areas of the negative consume all the original reducing agent that is locally available, and then stop converting silver halide to silver metal. Meanwhile, the underexposed areas have a relative abundance of reducing agent (because there's been less activation of silver halide molecules), and develop further. The reactions go more or less to completion, which is why timing is not so crucial. Compensating, two bath developers work because there is limited substrate for the reaction. In contrast (heh!), regular one bath developers have a huge excess of substrate, so timing and temperature of the reaction is critical to limit the reaction. Agitation should not be a big factor for compensating developers, and more of a factor in single bath developers.

Leigh
15-Apr-2014, 20:09
The "compensation" occurs when the film leaves the developer. There is a fixed amount of it soaked into every portion of the film. Then, in the second solution, which is an alkali activator, the heavily exposed areas of the negative consume all the original reducing agent that is locally available...
This is precisely my point.

How do you define "locally available" in a rotary processor that's constantly refreshing the liquid in contact with the film?

In a rotary processor, the term "original" (as above) is meaningful only when it refers to the entire volume of developer, not to a portion thereof.

- Leigh

Cor
16-Apr-2014, 06:44
As I understand it:

First the film is put in the Jobo for rotary processing and filled with reducer for a certain amount of time, temperature, rotation speed.

Then the tank is completely drained, leaving only the wet, soaked with reducer, film behind (finite amount of reducer) . Obviously no water wash in between.

Last the alkali (B) is added to the tank and rotated, and development takes place almost instantly as I understand from Sandy.

If I did not understood it correctly, I am sure more experienced practitioners will chime in.

Best,

Cor

This is precisely my point.

How do you define "locally available" in a rotary processor that's constantly refreshing the liquid in contact with the film?

In a rotary processor, the term "original" (as above) is meaningful only when it refers to the entire volume of developer, not to a portion thereof.

- Leigh

Leigh
16-Apr-2014, 07:18
OK. My error. I got the roles of the components reversed.

Sorry.

- Leigh

jbenedict
16-Apr-2014, 10:47
As I understand it:

First the film is put in the Jobo for rotary processing and filled with reducer for a certain amount of time, temperature, rotation speed.

Then the tank is completely drained, leaving only the wet, soaked with reducer, film behind (finite amount of reducer) . Obviously no water wash in between.

Last the alkali (B) is added to the tank and rotated, and development takes place almost instantly as I understand from Sandy.

If I did not understood it correctly, I am sure more experienced practitioners will chime in.

Best,

Cor

+1

BradS
16-Apr-2014, 13:40
.....Two-bath D23 and D76 act a bit different than Diafine and Pyrocat-HD in that the sulfite adds enough pH to activate slightly metol. With Diafine and Pyrocat-HD the pH requirements of the primary reducers is very high so nothing takes place in terms of image formation until the film hits Solution B.


Sandy

This is an important distinction that, I think, too many people gloss over or completely fail to grasp. There is a big difference between a a true two bath / divided developer and (some variant of) D-23 followed by an alkaline after bath. The latter cannot really be considered a divided developer. When the first bath is (some variant of) D-23 development very definitely takes place in the first bath. It is for this reason that I think it incorrect to call Stoekler's, the Leica two bath and Thornton's divided developers. These are really just D-23 with an alkaline after bath.

blueribbontea
16-Apr-2014, 14:01
Does it follow that in a true 2 bath developer, in the second bath, agitation is more or less irrelevant, and that timing (duration) should be done to exhaustion; the exhaustion of the reducing agent? Or would agitation be done simply to avoid unevenness of reduction?

Bill

sanking
16-Apr-2014, 14:47
Does it follow that in a true 2 bath developer, in the second bath, agitation is more or less irrelevant, and that timing (duration) should be done to exhaustion; the exhaustion of the reducing agent? Or would agitation be done simply to avoid unevenness of reduction?

Bill

The most important requirement of the second bath is that there is good agitation for the first 30-45 seconds. After that, it does not seem to matter very much how you agitate, if at all. Regardless of agitation method shadow density will increase for three or four minutes in the second bath. After about four minutes, however, the film may begin to stain so prolonged time in Solution B serves no purpose, and may be harmful to image quality.

Sandy

blueribbontea
16-Apr-2014, 14:49
Thanks Sandy.

Bill

stawastawa
16-Apr-2014, 14:50
Now that everyone is on the same page for how divided development works, here's a question. Since the shadows have an abundance of developing agent (A), does that agent diffuse out into (B) and allow some slight further development of the highlights?

I think this could be rather simply tested... Shoot a scene with a small highlight in one corner and the rest very dark. Then move the camera so that the bright highlight is most of the scene. The two highlight areas should be the same density when developed (assuming that both negatives originally imbibed the same amount of B, and that sufficient time is spent in B to allow for the possibility of diffusion).

AndI too am curious to hear about how people print (optically) these compressed negs.

Leigh
16-Apr-2014, 15:00
Shoot a scene with a small highlight in one corner and the rest very dark.
One point in developing negatives is that times are based on negs with "average" overall density.
Processing a neg that is predominantly dense or thin may require adjustment of development time or method.


AndI too am curious to hear about how people print (optically) these compressed negs.
Perhaps you mis-understand the purpose of compensation.
It's used to retain detail in highlights that might otherwise blow out.

A compressed negative should print normally on grade 2 paper, unless other factors are present.

- Leigh

stawastawa
16-Apr-2014, 15:26
One point in developing negatives is that times are based on negs with "average" overall density.
Processing a neg that is predominantly dense or thin may require adjustment of development time or method.
- Leigh


I think true two bath developers would use the same development for the two negatives. But I am curious what frequent users have to say.

Leigh
16-Apr-2014, 15:35
Yes, two-bath developers would likely not require adjustments.

My error. I was thinking in broader terms, not considering the thread title.

- Leigh

jkates
17-Apr-2014, 07:39
There is some data on the Stoeckler 2-bath developer available on this site. Go to the main page, and click on the Stoeckler Two-Bath link. The data indicate that some development takes place in the first bath, but that the pH and duration of the second bath have a larger influence on the development of both the shadows and the highlights. However, for all development times there is a clear bend in the D log E curve where the slope for the shadows is steeper than the slope for the highlights.

Jim Kates

Dietrich Floeter
28-Jan-2015, 12:09
I am test processing in D-23 using a few different methods from a variety of sources. Using the Stoeckler method, I have found a need for a 1 ⅓ stop exposure increase is required. Jim Kates writes that no increase is necessary and maybe someone has a notion as to why my exposures are so long. Could it be the Borax versus Kodalk?

stawastawa
12-Feb-2015, 04:51
I assume your indication of needing more exposure is based on developing the same shot in 'regular' developer.

d23 is slow to act, so maybe you just need more time...

curious

esearing
15-Feb-2015, 06:33
observations from my limited experience with HP5 and Diafine vs HC-110

Diafine - can expose at box speed for normal contrast scenes and box - 1/2 stop for bright scenes. Negative is very flat for scenes of low contrast or similar tones
- recommended for scanning of negatives since it tends to compress the contrast overall.
- I use it for roll films where I tend to "bracket".
- I also use it for new film testing or when I have limited time since I can not always take the time to control temperature.
HC110
expose at 1 to 1.5 stops slower than box speed(over expose), works for all scenes but surpasses Diafine for low contrast scenes.

For sheet film 4x5 negatives in normal contrast scenes with equivalent exposures there is not much difference . Extreme contrast I prefer the Diafine, low contrast I prefer hc-110.

Enlarging on Ilford multigrade paper the Diafine negatives usually need a higher contrast filter than the HC-110 negatives.