Divided developer pros and cons

[Leigh]

OK. My error. I got the roles of the components reversed.

Sorry.

- Leigh

[jbenedict]

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]

.....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]

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]

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]

Thanks Sandy.

Bill

[stawastawa]

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]

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]

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]

Yes, two-bath developers would likely not require adjustments.

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

- Leigh