Barry Thornton's Two Bath Developer question Part 2

[Rudeofus]

Michael R.'s curves show that BTTB is a low contrast developer with a more or less straight characteristic curve (yes, I was surprised by that, too). What I don't understand is why David Allen wasn't able to adjust his contrast by choosing different paper gradations. I've done some tests with Foma 312 paper and a 4x5" Stouffer wedge, and the differences in dynamic range with different gradations are surprisingly high.

 

[David Allen]

Michael R.'s curves show that BTTB is a low contrast developer with a more or less straight characteristic curve (yes, I was surprised by that, too). What I don't understand is why David Allen wasn't able to adjust his contrast by choosing different paper gradations. I've done some tests with Foma 312 paper and a 4x5" Stouffer wedge, and the differences in dynamic range with different gradations are surprisingly high.

Dear Rudeofus,

Why would I want to complicate things? BTTB developer is no more a low contrast developer than many others - it is simply a developer that works wonderfully with images exposed over quite a range of subject luminances. Why would I (want to 'improve' things when everything works so well??) want to change things when I get the results that I want?

I see the options available when printing as being a way of interpreting the definition of how I an image to 'look' and how I want my prints to be seen. In this case, a negative that presents a wide range of opportunities is the 'best' negative for me as (I can reproduce the scene how I want to).

Bests,

David.
www.dsallen.de

 

[David Allen]

Michael R.'s curves show that BTTB is a low contrast developer with a more or less straight characteristic curve (yes, I was surprised by that, too).

Sorry, I do not think so.

Bests,

David
www.dsdallen.de

 

[Rudeofus]

Michael R.'s curves show that BTTB is a low contrast developer with a more or less straight characteristic curve (yes, I was surprised by that, too).

Sorry, I do not think so.

Look at his plot (there was a url link here which no longer exists). His plot shows a gamma of (1.8 - 0.4) / (3.9 - 0.9), which is about 0.47. Call it whatever you want, but that's a low contrast developer in my book. Not POTA type low contrast, but lower than normal.

 

[el wacho]

stoeckler a bath is not thornton's a bath and stoeckler b bath is not thornton's b bath. that is why, all things being equal, thornton's two bath will give you a negative with more contrast than stoeckler's ie Michael's data is not, sensitometrically speaking, applicable.

 

[Bill Burk]

Michael R 1974,

At first glance I thought your curves were normal contrast but now I see the x and y scales are scaled a little different. The contrast is a little low as Rudeofus pointed out. But hey, I know you are just showing one example test of one two-bath developer trying a few variations of bath B...

I agree, you can get any contrast from any developer, and I'm sure there are limitations to that and points to discuss.

My sister gave me a stack of old reference pocket references last weekend, and in one of them (The Camera Pocket Photo Guide 1942) D-76 is listed as a "low-contrast" developer. I haven't figured out whether that's a typo (the book does contain typos), or whether I should take it as a newly learned "fact" that D-76 is "low contrast"... I never thought of it that way.

David Allen,

I appreciate when you name a photographer's style. In the end it is the "Results" of photographers you admire that should guide a choice of developer (if it's relevant, some photographers don't focus much on chemistry). Anyway, I love taking side-trips and learning another photographer. Keep bringing up examples whenever you want to illustrate a point, I enjoy it.

I believe even though you say you don't follow the curves and sensitometry school of thought, you have a scientific approach... Your description of Minimum Time to Maximum Black is a good example, that's a logical way to get the details you want to catch on film... It sounds like a historic speed determination method... a little like Fred Picker of Zone VI studios, and the Zone System, but tailored to your own style. I support your right to determine film speed your own way, "freedom of speed" is like "freedom of speech" to me...

Historically there were lots of ways to determine film speed and some of them had a touch of "see what makes the least visible image on the print"... Later sensitometry and curves were used as the basis for standards and we no longer had to have cross-reference charts to the different kinds of speed testing methods. My 1942 book lists "Weston" "General Electric" "H&D" and "American Scheiner" speeds, and calls "High Speed" films "Weston 100" and "GE 150" - I think that describes a film that today would have a box speed of ISO 200.

And you would shoot it at 100... So would I.

 

[el wacho]

my statement still stands. ALL THINGS BEING EQUAL the extra 1.5 gr of metol in thorton's does yield a negative of greater contrast. that is why Thornton modified the Stoeckler two bath. Rudeofus is right in saying that Stoekler is a low contrast developer. Dave Allen is right for asserting that Thornton's two bath is "is no more a low contrast developer than many others". I agree with Dave here and presenting stoeckler data as refutation or Michael's " they are not much different " isn't persuasive. Yes what Michael says about two bath developers being able to produce a desired contrast index by extending time in bath A is true and not a fix nor inherent feature of any particular two bath BUT when all things are equal - times temperature agitation regime etc d23 is contrastier than thornton's which in turn is contrastier than stoeckler. why, because the level of imbibed metol in the film present for the B bath to do the rest of the development make a significant difference at the enlarger. I have seen this difference an have adjusted A baths according to the different films I use.

 

[Rudeofus]

El wacho, if BTTB as used by David Allen gives normal contrast and a straight curve, I wonder why he claims he got such different results compared to other developers.

 

[el wacho]

Dave Allen answers some of your question at post 91. I suspect though that his assertion is not sensitometric in nature and that you have understood his assertions as purely sesitometric in nature. I suspect that his satisfaction with thornton's two bath, like my own, lies in the impression of improved local contrast that thornton's two bath has over, say d76 1:1. i'm not certain that a stouffer wedge could furnish data in the area of local contrast. yes. two developers can achieve the same contrast index but yield qualities on print that are beyond the scope of sensitometry. perhaps tanning and staining vs mq developers is a good example of this.

 

[el wacho]

I've tested the difference that 1.5g of metol makes. i'm not speculating nor am I saying it necessarily does. I am saying it does because I've tested it. if I remember correctly, PE suggested that 'reformulating' ( what I would call adding a little more metol to) the developer according to the gelatin's absorbing capacity was a better approach. I intuitively arrived at that conclusion and was pleased to see PE say something in a similar vein.
Nothing personal Michael but I haven't seen any of your data contradict my testing, in particular to the issue of metol levels in bath A and its irrelevancy to contrast. i'll most definitely be continuing with the evidence I have produced in my darkroom. I invite any one to mix two A baths (a stoeckler and a thornton) and two 12g sod metaborate B bath and see for themselves.

"it says nothing about whether developer X is more or less contrasty than developer Y"
never asserted it and it has never been my concern. I made a basic assertion - more metol more contrast, all things being equal.

perhaps MrBrowning just unknowingly placed the highlights too high on the film and beyond the reach of any developer to retain tonal separation.
Michael is right for attempting to disperse any myths regarding two bath development but the op's original question was the real matter at hand.

 

[MrBrowning]

I want to say thanks to everyone for there comments. I have learned a lot and still have a lot of questions but the biggest thing I have realized is I need to do more testing.
Testing in regards to what Michael says and what Thornton said so I can have a better understanding of both. Plus it would be fun.

el wacho,
I may have very well placed the highlights to high. I metered strictly for the subject without thought to highlights (since at the time they didn't seem as important as capturing the moment).

 

[Rudeofus]

Dave Allen answers some of your question at post 91. I suspect though that his assertion is not sensitometric in nature and that you have understood his assertions as purely sesitometric in nature.

I just reread posting #91 and it says nothing about micro contrast or sharpness, and everything about the fact that he can get printable negs even if different frames on a roll are exposed under very different lighting conditions. I would interpret this as "gives me more latitude with normal development in high contrast scenes", i.e. a property well described by H&D curves.

 

[David Allen]

El wacho, if BTTB as used by David Allen gives normal contrast and a straight curve, I wonder why he claims he got such different results compared to other developers.

BTTB gives the contrast that I want. Whether this is normal is another matter. As for it producing a straight curve - don't ask me.

The reasons that I got results with BTTB that pleased me more than the other developers is simply I got the results that I wanted straight away with BTTB and I didn't with the other developers.

At the core of developer choice is getting the results that suit one's work - as I explained in post#91

For me the key things that I want from a developer are:

• Relatively low levels of grain (given that I am using 6 x 7 film printed onto 16" x 12' paper)
• Good level of apparent sharpness
• Reasonable levels of acutance (impossible to define/explain but I know what I want)
• Good tonal structure (again impossible to define/explain but I know what I want)
• Being sure that I can place the dark shadows (where I want to retain detail) exactly where I want them secure in the knowledge that the developer will control the highlights (i.e. will not cause me to have very dense highlights that are hard to print or are virtually impossible to print).
• That the developer can cope with the variety of scenes and subject brightness ranges that exist on a single roll of film.

Bests,

David
www.dsallen.de

 

[David Allen]

I just reread posting #91 and it says nothing about micro contrast or sharpness, and everything about the fact that he can get printable negs even if different frames on a roll are exposed under very different lighting conditions. I would interpret this as "gives me more latitude with normal development in high contrast scenes", i.e. a property well described by H&D curves.

Micro-contrast and sharpness were discussed in post #75 when commenting on the image that I included with this post.

I believe that, over the course of this thread, I have explained a wide range of issues related to BTTB and why I like using it. Of course, I could have done everything in one enormous post but I don't have the time write such a long text and suspect fellow APUG members wouldn't have the time to read it!

Bests,

David.
www.dsallen.de

 

[Harry Lime]

For me the key things that I want from a developer are:

• Relatively low levels of grain (given that I am using 6 x 7 film printed onto 16" x 12' paper)
• Good level of apparent sharpness
• Reasonable levels of acutance (impossible to define/explain but I know what I want)
• Good tonal structure (again impossible to define/explain but I know what I want)
• Being sure that I can place the dark shadows (where I want to retain detail) exactly where I want them secure in the knowledge that the developer will control the highlights (i.e. will not cause me to have very dense highlights that are hard to print or are virtually impossible to print).
• That the developer can cope with the variety of scenes and subject brightness ranges that exist on a single roll of film.

Bests,

David
www.dsallen.de

Same here. I shoot mostly street and documentary and there isn't always time to nail the exposure correctly. BT2B is idiot proof in operation, highly consistent and produces a beautiful, printable negative 90% of the time, even if your exposure varies a little across a roll. It's ability to hold on to highlight detail in high contrast situations is of the utmost value to me. This last point is the main reason why I still shoot film and have not switched over to digital. Two bath developers can give me an endless, smooth rolloff in to white that I just don't see in digital.

 

[Xmas]

I've tested the difference that 1.5g of metol makes. i'm not speculating nor am I saying it necessarily does. I am saying it does because I've tested it. if I remember correctly, PE suggested that 'reformulating' ( what I would call adding a little more metol to) the developer according to the gelatin's absorbing capacity was a better approach. I intuitively arrived at that conclusion and was pleased to see PE say something in a similar vein.
Nothing personal Michael but I haven't seen any of your data contradict my testing, in particular to the issue of metol levels in bath A and its irrelevancy to contrast. i'll most definitely be continuing with the evidence I have produced in my darkroom. I invite any one to mix two A baths (a stoeckler and a thornton) and two 12g sod metaborate B bath and see for themselves.

"it says nothing about whether developer X is more or less contrasty than developer Y"
never asserted it and it has never been my concern. I made a basic assertion - more metol more contrast, all things being equal.

perhaps MrBrowning just unknowingly placed the highlights too high on the film and beyond the reach of any developer to retain tonal separation.
Michael is right for attempting to disperse any myths regarding two bath development but the op's original question was the real matter at hand.

Dave answered the OPs question about n-1...
Michael provided H&Ds
You are doing bold text instead of H&Ds... please publish your H&D.

 

[el wacho]

Yawn...

 

[Xmas]

I understand why Dave relies on a successful test shot for a film, sceane, developer combination.

And why some people take test rolls to dial in a new film developer combinations.

But with a H&D like Michael's or similar information that Forma publish for their films I can spot the time temperature and EI for the shadow detail I want.

Alas the Forma information still leaves the highlights at risk (unknowns) and I need to use D25 or other low contrast soup with Forma films cause I burn highlights too readily.

I don't mind burnt highlights.

A post borax bath is an option which I now have more information for but Im going to need a step wedge...

A request for H&D was lazy me...

 

[baachitraka]

Do you meant Foma instead of Forma?

 

[Xmas]

Do you meant Foma instead of Forma?

http://www.foma.cz/en/catalogue-fomapan-400-action-detail-272

data sheet is PDF to down load

details are on 2nd page

sorry about dyslexia

 

[baachitraka]

I will use those curves for the reference. Personal testing may result in something different from what the manufacturer can offer.

Personally love Fomapan 400 for its grain esp., in Rodinal.

 

[Xmas]

Yes the grain is nice in Rodinal.