Low contrast developer for P30

[Milpool]

Apologies for the annoying / dismissive response. The "BTTB" thing gets to me for some odd reason.

The BTTB formula I've seen is a trivial / insignificant adjustment to Adams's version of divided D-23. The BTTB first bath is essentially a slight dilution of D-23 which doesn't make a difference. From a photographic perspective the altered concentration of metaborate in in the second bath also makes no difference. The Stoeckler version (and several others) also give the same sensitometry results.

Sorry again for the topic diversion versus suggested uses for two-solution development for this film.

Please elaborate.

 

[Alan Johnson]

BT explained his variation:

Barry Thornton’s Writings - Geoffrey Billett Photography

FINE NEGATIVES, AUTOMATICALLY The clue to a fine monochrome negative is to give so much exposure as to give rich detail in the shadows, and so little development as to avoid highlights becoming too dense to print with subtle graduation. The vast majority of the negatives arriving in the Fine...

sannyassa.co.uk

 

[Raghu Kuvempunagar]

By modifying the time in the first and second baths, it should be possible to get very similar results with AA and BTTB.

One criticism of these two bath developers, from a sensitometry perspective or otherwise, could be that there is no principled or wellfounded crtiterion for splitting the development between the two baths unlike a truly divided developer where all development happens only in the second bath.

 

[Milpool]

By modifying the time in the first and second baths, it should be possible to get very similar results with AA and BTTB.

One criticism of these two bath developers, from a sensitometry perspective or otherwise, could be that there is no principled or wellfounded crtiterion for splitting the development between the two baths unlike a truly divided developer where all development happens only in the second bath.

There is though. With this type of two-bath (ie where bath A is a fully functioning developer), contrast is controlled by development time in bath A. That's about all there is to it. Bath B goes to completion/exhaustion but is not a control for contrast.

Some illustrations:

 

[Andrew O'Neill]

Apologies for the annoying / dismissive response. The "BTTB" thing gets to me for some odd reason.

The BTTB formula I've seen is a trivial / insignificant adjustment to Adams's version of divided D-23. The BTTB first bath is essentially a slight dilution of D-23 which doesn't make a difference. From a photographic perspective the altered concentration of metaborate in in the second bath also makes no difference. The Stoeckler version (and several others) also give the same sensitometry results.

Sorry again for the topic diversion versus suggested uses for two-solution development for this film.

Thanks, Milpool.

 

[gorbas]

Thank you very much Milpool for sharing those HD curves! That is exactly what I would like to see for the long time.
What was time in Bath A? Was it constant or variable?
I'm surprised to see that same amount of borax and kodalk had basically the same effect.
From my experience, 4 min in B gives very different results from borax and kodalk.
In some other thread I mentioned that I tested only B development (in kodalk) after 5-6 rolls of film and I had decently developed film.
So, all that talk about carryover of A being neutralized/exhausted in B, is not right. It stays there and it's active.

 

[Raghu Kuvempunagar]

@Milpool: In connection with Figures 2 and 3, do you also have the curve for a plain water bath B?

@gorbas: to avoid the inconsistencies due to carry-over, a one-shot second bath such as one made up with Ascorbate can be used.

 

[gorbas]

Raghy, yes, I made one shot B bath from recipe you give me. It worked well but grain is a bit on rough side.

 

[Milpool]

Thank you very much Milpool for sharing those HD curves! That is exactly what I would like to see for the long time.
What was time in Bath A? Was it constant or variable?
I'm surprised to see that same amount of borax and kodalk had basically the same effect.
From my experience, 4 min in B gives very different results from borax and kodalk.
In some other thread I mentioned that I tested only B development (in kodalk) after 5-6 rolls of film and I had decently developed film.
So, all that talk about carryover of A being neutralized/exhausted in B, is not right. It stays there and it's active.

Time in bath A was constant - I would have to go back to my old notes to be sure but I think it was 4 minutes.

I didn't reuse bath A or bath B in any of the experiments. It's difficult to predict whether or not carryover into bath B would cause it to develop on its own. It would depend on a number of things such as the type of A bath, volume carried over, pH of B bath and time between uses of B bath (at the pH of say metaborate, an extremely dilute metol-sulfite solution is going to oxidize quite readily).

 

[Milpool]

@Milpool: In connection with Figures 2 and 3, do you also have the curve for a plain water bath B?

@gorbas: to avoid the inconsistencies due to carry-over, a one-shot second bath such as one made up with Ascorbate can be used.

I didn't do any trials with a plain water bath. I probably should have tried it but eventually lost interest (these two-solution experiments were just attempts at satisfying my own curiosity regarding how the work since reliable information is virtually nonexistent, but it was not a technique I planned on using in my photography)

 

[Raghu Kuvempunagar]

No worries. The data you have shared is useful.