Beginner Developing time vs developing dilution

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Dragos Ioan Anti
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#1
Hi I'm John,

I can't find anyware on the web the answer to the question:

Does developing a b&w film half the required time will give the same result as when I use the same developer at double dilution but with the normal development time ?


I've read a few books about developing b&w film, but each one of them treats these 2 subjects separately.

Hopefully this is not one of those silly questions that you hear every day.

Thank you
 
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Richard
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#2
Hi I'm John,

I can't find anyware on the web the answer to the question:

Does developing a b&w film half the required time will give the same result as when I use the same developer at double dilution but with the normal development time ?


I've read a few books about developing b&w film, but each one of them treats these 2 subjects separately.

Hopefully this is not one of those silly questions that you hear every day.

Thank you
It doesn't work like that John. I guess there must be a relationship between time and dilution but it will not be linear and finding any reliable data would be difficult as it's not standard practise. You might find something on time vs temperature to account for working in hot climates but that will also be non-linear.

You may have more luck posting in the Film section. Welcome to TP :)
 
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John Anti
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#3
"It doesn't work like that John. I guess there must be a relationship between time and dilution but it will not be linear and finding any reliable data would be difficult as it's not standard practise. You might find something on time vs temperature to account for working in hot climates but that will also be non-linear.

You may have more luck posting in the Film section. Welcome to TP :)"

Thank you Richard
 
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#4
Once upon a time, long, long ago.... when film was all we had, and the internet hadn't been invented; My day-job was working on the development of missile guidance systems, at night, I went troglodyte and descended into my darkroom.....
Enthused about push-pull processing, I tried to 'crack' the mathematical formula, between Time, Temp and Concentration for I think it was E6 slide film..... and conveniently some-one had dumped one of these new fangled "Personal-Confounders" on my desk...
I recall 'some-one' a lot more senior to me saying "You can use this", and being a young, still insecure new recruit, and not sure if it was a question or a statement, meekly said, unadvisedly, "Yes"... well, they had shown us some at Uni, and I had switched one on once, and had this vague recollection that you needed to 'load a program' to do anything else with it.... and that normally took longer than our lecture slots, so was as far as we ever got..... I remember sitting reading a lot whilst a tutor fiddled with wires and a screen flashed, but that was about it, Lol!

Anyhow..... This Personal Confounder landed on MY desk... shortly followed by a skip load of manuals with spiral binders! And unperturbed, I started taking them home, and reading them whilst solutions did stuff..... and when I got stuck.... talking to the woman in the office, who lived in a pen in the corner, behind a wall of cardboard boxes, who occasionally surfaced for coffee, and every-one else smiled at, and said "Dunno... I THINK she works here" when you asked who she was.... "LESLIE!" her name just came back to me over the millennia!

Anyway, she spotted that I was 'doing something' with this 'ere personal-confounder, and cough me at the coffee machine to ask what the heck I was up to, this 'spread sheet' I had written a macro for and left running for a week, made no sense......
BASICALLY, I was trying to extrapolate from the Time/Temp/Conc instructions from probably an E6 dev kit, the full 'curve'... and it was getting strange..... This piqued our Leslie's interest, and she picked up on it, and said she'd have a look....
About a month later, she came back, and announced, "It's a Polynomial!" and showed me a curve that looked like the run of a roller-coaster...... and then went on to explain, how the 'problem' had piqued a few interests, and via our networked connection with JANET and NATO.... the 'problem' had landed on the Personal-Confounder of some-one at NASA..... or maybe the NSA, I'm not entirely sure... when she spoke, it was a 'little' frantic, and probably in some wiered language with a name like corbalt or something, that was probably an acronym for something else;......

ANYWAY.......

The upshot was, that the mathmatical formula for the time/temp/conc relationship, was a very very complicated one with the resultant 3-D graph, looking something like an elevation map of the Himalayas, without a straight line relationship virtually anywhere..... the 'bits' that you got in the developing instructions were a sort of flat-earth simplification.... you know.... sort of like the canal tunnel.... the water is 'flat' isn't it? But over a 2 mile tunnel, if you bore it 'flat' the barges get stuck half way down, cos the roof is effectively an inch lower in the middle, cos the water ISN'T actually flat, it follows the curve of the earth.... just 'seems' flat or flat-enough cos of the small scale we usually see it over.....

That's pretty much how the time/temp/conc relationship for developing a film works, and the 'sort' of halve the concentration, so double the time, relationship only sort of works over pretty small limits, and even the developing instructions show that the relationships aren't 'so' linear over even that short of a scale, like a 15 minute dev time.....

So the answer, basically, is No... maybe, possibly, its too complicated to say!

Yes, it 'should' be simpler for B&W, with development temperature apparently not being a factor.... only it IS... its just back to that 'scale' again, and the flatness of its effect over the limits of what might be considered 'room temperature'.

So... no... NOT the sort of question that pops up every day!

Empirically from folk that spent even more time in the dark than I did, would suggest that adjusting the time and concentration of the dev on B&W, you DON'T get the same effects... perhaps similar, but, exponents of the art would spend hours trying different permutations of concentration and time, and even temperature, in the dev on the film, and then even more still with the added factor of paper grade in developing the prints they made, to get more or less total separation or density in different bits of the exposure.....

The way that halide film works, from the outset, was described to me as like striking a match..... and trying to STOP it from burning all the way...... silver-halide wants to either stay silver halide, or it wants to turn into silver oxide.... it turns into silver oxide when its tickled by light; it does not have a half way state, its one of the other.... with no in-between, so the whole science is based on scales of 'bulk' and how much of a reaction actually happens and out of however many moles of silver-halide, how many react to silver-oxide, and you get shades of grey from the proportion of how much is allowed to turn black compared to how much stays white..... where-upon the anomalies lie, because the maths that might give a more liniar relationship betwen time/temp/conc are now given a forth variable, the degree of complete-reaction...... and its that degree of in-completion that's actually what we are trying to achieve and control in chemical-photography... and why so much doesn't translate to binary digital! ;-)
 
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#5
Hi I'm John,

I can't find anyware on the web the answer to the question:

Does developing a b&w film half the required time will give the same result as when I use the same developer at double dilution but with the normal development time ?


I've read a few books about developing b&w film, but each one of them treats these 2 subjects separately.

Hopefully this is not one of those silly questions that you hear every day.

Thank you
Short answer - no! Regarding time vs dilution you can take a look at something like Ilford ID11 data sheet from their website. They give times for stock, 1+1 and 1+3 as well as film speeds at different times and dilutions. These will all get you a useable neg but there will be differences in the 'curve'. Additionally depending on the developer there will be differences in grain and acutance (edge contrast). So 'Yes' , but not in a simple way.
 

StephenM

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#6
I don't know which books you've read about developing, but this reference indicates why the answer to your question may not be straightforward without specifying the actual developer.

If you haven't read Grant Haist's Modern Photographic Processing I might take a look in my copy to see if there are any pointers as it's an interesting question.
 
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#7
If you are trying to minimize waste by using high dilutions you might want to look at Ilfords "one shot" developer.
It's about as dilute as it gets 1+19 as far as I know.
 

StephenM

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#9
It's an interesting question in photographic chemistry that I may well follow up some time, but not now.
 
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Cobra

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#10
Threads merged and tidied

@John Anti please don't start 2 threads on the same subject it dilutes the answers
 
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Richard
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#11
Short answer - no! Regarding time vs dilution you can take a look at something like Ilford ID11 data sheet from their website. They give times for stock, 1+1 and 1+3 as well as film speeds at different times and dilutions. These will all get you a useable neg but there will be differences in the 'curve'. Additionally depending on the developer there will be differences in grain and acutance (edge contrast). So 'Yes' , but not in a simple way.
I stand corrected. It's a long time since I read an ID11 instruction sheet :D
 

sirch

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#12
The datasheet for HC 110 gives a wide range of dilutions. I always use dilution B so I have never bothered looking at the others but I just took a look and whilst dilutions A to F are listed only times for dilutions A and B are given for common films.

https://www.digitaltruth.com/products/kodak_tech/j24_HC-110.pdf
 
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#13
When I used D76 /ID11 (same stuff different maker) I usually used it full strength for Large and medium format in 3 gallon tanks.
However if I was using single film tanks I would use it either 1-1 or 1-4. And Data sheets were available for these dilutions. with separate tables for each temperature and gamma.
But I never saw any way to relate one to the other that would give a standard result.

The three gallon tank was perhaps the most economical, as you could purchase replenisher. which you used to top the tank back up to level after each use. This ensured that it was always fresh and the time of development remained the same. like wise I always used everything at 72 degrees F... 20 C with use of a temperature controlled water bath.
I used the 1-1 and 1-4 dilutions ( and chuck) when I wanted to increase the sharpness and shadow detail. which is one benefit of higher dilutions and lower agitation. Though the dilution has little affect on Granularity with most developers, where as high temperatures with more active developers massively increases grain size.

It has massive advantages to only move one variable at a time.
A fixed dilution and temperature... then only adjust the time-- which will affect gamma, density and to some extent granularity... which are quite enough changes to get familiar with.
 
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StephenM

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#14
Having thought about it, given the exact phrasing of the question, my answer would be "no". Development begins at the surface of the emulsion, and proceeds towards the base as developer diffuses into the emulsion. This takes time. At lower concentrations, there will be less active developing agent, so less developer will reach the base; but depending on the activity of the agent, the increased time might equalise the quantities.

This is purely speculation, based on the factors I mentioned. What is certain is that the effects of increasing the development time and increasing the dilution don't give the same results when the base time for the normal dilution is the standard developing time, rather than half it.

There may well be a definitive yes/no answer, and it may well also be that my reasoning is false due to unconsidered factors. I don't recall ever coming across this exact question before.
 
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#15
Thank you StephenM, your answer makes sense... I should've thought about: "Development begins at the surface of the emulsion, and proceeds towards the base as developer diffuses into the emulsion. This takes time."
 
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John Anti
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#16
Basically, I've shot a few images with a home made pinhole camera... for the landscapes the developing time was cut to half, while for the "portrait" the developer was double diluted but I kept the development time to normal. The results seem to be (more or less) the same. The tint is from scanning in RGB mode. The developer is Ilfosol 3, the films are HP5.
 

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