Stock D-76 and Ilford HP5 @ box speed, 18 minutes development time, densitometer results

[SergioVileda]

Hi,

I've made a controlled lighting setup with a light box and gray scale pattern from 0 to 10 stops.

I was doing single shots of HP 5 with same exposure parameters but different development times.

I was doing single frame development in 12,5mL of stock DIY D-76.
12,5mL comes from my approach, that I normally develop 36 frames in 0,5 L of stock D-76.
I just divide 0,5L / 40 = 12,5mL of developer per frame.

I found that when I develop for 7:30 minutes, my negative comes with dynamic range of about 5 stops.
I gradually increased development time up to +170%, and found that dynamic range goes up to 9,5 stops.

I built some sort of H/D curves and at max dev time, curve look quite good, I would say.
There details in both shadows and highlights.

Did any one tried to go that far with development time?
Does it make any sense to any one?

160% shows lower performance, probably because developer was 24h old and was stored in a bottle with a lot of air


Looking the characteristic curve of HP5 Plus film

I can see that maximum density is around 10^2 = 100 times ~ 6-7stops
to achieve it 10^4 exposure must be provided ~ 13-14stops
to achieve it 4-1.5 = 2.5 log exposure has to be done, which 8-9 stops

in my test I was able to provide 10 stops of exposure, which is around 10^3 = Relative log exposure = 3 and expected density according to datasheet is 1.5 = 5 stops.
looks like my 0% curve is very close to one in datasheet

 

[BCM]

Your results are a bit typical of the conditions you are describing. You'll see some reduction of the film developer effects as you extend development (to exhaustion). Are you using a dentisometer? You might read (if you haven't) Beyond the Zone System by Phil Davis which will help you not only refine your plots but also get a better sense of both expanded and contracted (-) development times around a "normal". Your tests show the effect of film development time which is certainly important but that needs to be carried to paper to get the full understanding. That said, your results are similar to mine (with less detail in the plots) for that same combination. The real difference is in the shadows where separation is less obvious in my tests (the toes are more closely grouped with extended development affecting highlights).

 

[SergioVileda]

Your results are a bit typical of the conditions you are describing. You'll see some reduction of the film developer effects as you extend development (to exhaustion). Are you using a dentisometer? You might read (if you haven't) Beyond the Zone System by Phil Davis which will help you not only refine your plots but also get a better sense of both expanded and contracted (-) development times around a "normal". Your tests show the effect of film development time which is certainly important but that needs to be carried to paper to get the full understanding. That said, your results are similar to mine (with less detail in the plots) for that same combination. The real difference is in the shadows where separation is less obvious in my tests (the toes are more closely grouped with extended development affecting highlights).

thank you for feedback.
Yes, I'm using desitomer to measure densities of the negative.

I'm surprised, that Ilford recommends 7:30 as normal development time, while my results show, that +120% (16:30) gives much better dynamic range.
Maybe the reason is that I develop single frame in 12,5ml?
I my worflow, I'm using 0,5L of developer per single roll of film.
So, divide 0,5 / 40 frames gives 12,5ml per frame.
Do you know if that math makes any sense?

 

[bernard_L]

while my results show, that +120% (16:30) gives much better dynamic range.

What do you call dynamic range? Seems that what you call dynamic range is the range of negative densities (the vertical axis in your plot, counted in f-stops --nothing wrong with that).

What I (and, I expect, most people) call dynamic range, is the range of scene brightness that you can capture on film. Your 0% curve (datasheet nominal) is still rising linearly at abscissa "10", loosely corresponding to Zone X. Accordingly, I would say that the dynamic range (following the commonly accepted definition) of HP5 is >=10 stops; on the her hand, your curve for +120% starts to roll off --shoulder off-- at exposure step 8. Not hitting a ceiling, but shouldering.

Plus, seems to me you have a problem with contrast.

and at max dev time, curve look quite good, I would say

Your curves for +140% or +160% seem, by eyeball, to have a contrast index of close to 1(!!!). The response of enlarging papers being what it is, even a flat-lighting scene would require grade 1 or 0.

What is the goal of your tests?

 

[SergioVileda]

What do you call dynamic range? Seems that what you call dynamic range is the range of negative densities (the vertical axis in your plot, counted

yes, on vertical axis range between min and max densities is shown.
this range is measured in log2's (steps) instead of log10's (density D values)
on horizontal axis represents expected values of densities (stops)
the closest match between expected and actual densities looks to be at +120-140% of recommended development time by Ilford.

 

[SergioVileda]

What do you call dynamic range? Seems that what you call dynamic range is the range of negative densities (the vertical axis in your plot, counted in f-stops --nothing wrong with that).

What I (and, I expect, most people) call dynamic range, is the range of scene brightness that you can capture on film. Your 0% curve (datasheet nominal) is still rising linearly at abscissa "10", loosely corresponding to Zone X. Accordingly, I would say that the dynamic range (following the commonly accepted definition) of HP5 is >=10 stops; on the her hand, your curve for +120% starts to roll off --shoulder off-- at exposure step 8. Not hitting a ceiling, but shouldering.

Plus, seems to me you have a problem with contrast.

Your curves for +140% or +160% seem, by eyeball, to have a contrast index of close to 1(!!!). The response of enlarging papers being what it is, even a flat-lighting scene would require grade 1 or 0.

What is the goal of your tests?

I'm just trying to fit as much information as possible into the negative, to have lots of details in highlights and shadows.
In my understanding, most details are captured at 45% degree inclination of the curve, when scene is mapped 1:1 to the negative (at least 9-10 stops of scene, whole scene is much wider of course).
Isn't it "good" to try to achieve this goal? To map most of of the scene to linear part of the curve and have contrast index lose to 1?

 

[SergioVileda]

I think I've got my problem. There is no need to mach 1 to 1 scene dynamic range to film densities.
Scene dynamic range should match film exposure range, that film can accept and produce density on linear part of the curve.

from this curve, Dmax - Dmin = 2.5-0.25 = 2.25 = 10^2 = 100 = 7stops, but this value is irrelevant
exposure range is Emax - Emin = 4.5-1.5 = 3 = 10^3 = 1000 = 10stops, this is how much scene dynamic range can be captured on the film.

My question is (was) do I develop film correctly in D-76, is 7:30 correct time, do I get same curve?
At 10 stops of exposure, I should get 7 stops of density.
I didn't, I get only 6 stops of density, that means film is underdeveloped.
I do get 7 stops of density at +30% development time.

My correct development time for HP5 should be 9:45.

@bernard_L @BCM, thank you asking me good questions

 

[bernard_L]

Capturing the scene brightness range is one thing. Then comes the choice of the negative contrast (gamma, CI, G-bar...) and development time.
- A long time (50, 70 years) ago the "normal" Contrast Index was about 0.65
- Nowadays, the majority opinion favors 0.55 or less
- Lower C.I. allows a larger dynamic range
- Lower C.I. is preferred by those who only scan their negatives and do not wet-print them
- If wet printing the density range of the negative (vertical axis) should match the dynamic range of the paper. Fortunately, the paper grades give some flexibility. The dynamic range of paper, quoting from

Paper Grades | Roger and Frances

At their most basic, paper grades could hardly be easier to understand or to master. Paper grades range from 00 (very soft) to 5 (very hard).

www.rogerandfrances.com

is:

Thus for example ISO(R) 60 corresponds to a log density range of 0.60 or 2 stops or 1:4 while ISO(R) 150 is a log density range of 1.50 or 5 stops or 1:32.

 

[ic-racer]

I found that when I develop for 7:30 minutes, my negative comes with dynamic range of about 5 stops.
I gradually increased development time up to +170%, and found that dynamic range goes up to 9,5 stops.

Perhaps a language barrier from the North Pole. Since the time of Hurter and Driffield, the dynamic range would be measured on the X-Axis, with density on the Y-axis.

 

[BCM]

I get your confusion. To answer the first question, You are making an assumption that fluid volume and active developer is linearly related to the film area. Think of it this way - a new 500ml mixture of developer will develop 1 35mm image with the same results as developing 36 exposures. At one point, it will start to measurably exhaust (as noted in the data sheets) but until then, the developer doesn't "know" how much film is being developed. Your concern would be valid after a few more rolls being developed.

Film speed isn't really based on dynamic range but instead a calculation. If you are printing, remember that most paper doesn't really have such a large range even with MG heads. The concept (Adams, Davis, etc) is that you want to expand or contract a SCENE based on development to then fit the range available by paper. In other words, a high contrast scene with a large EV difference between the highlights and shadows would require a lower development time to bring the film data into range with the desired paper. Conversely, a very low contrast scene would be subject to expended development to "stretch" the scene out to match the paper via longer development times. Your understanding is 100% regarding the film results you show BUT it is really related to the final results in the print.

 

[Romanko]

Isn't it "good" to try to achieve this goal? To map most of of the scene to linear part of the curve and have contrast index lose to 1?

It depends on what you are trying to achieve. If you are making a step wedge this could be a valid goal. When producing a photographic image there are other factors to consider including the shape of the characteristic curve, the contrast and dynamic range of your final print. Note how your higher CI curves have a distinct S-shape while the nominal curve is almost linear. Human eye is more sensitive to variation of lightness in the highlights so compressing them is often undesirable. If I didn't know what film and developer you were using I would choose the nominal (0%) curve for general pictorial use.

 

[Augustus Caesar]

First point: "dynamic range" refers to the difference between the loudest to the softest parts of a musical performance, and by extension, to a recording of that performance, and by further extension, to the signals derived from that recording. Extended even further, the term is used to the refer to the difference between the maximum signal and zero signal that an audio device can accommodate before severe distortion. It has been further extended to refer to the light-range capturing capacity of camera sensors. It cannot properly refer to any property of scenes. The term "dynamic" means changing from moment to moment, as in a performance of music.

There is no "dynamic range" in photography. What you do have, is subject brightness range (SBR), which can vary from one scene to another, or with changes in lighting (overcast, sunny, etc.).

This is usually expressed in stops.

Given a fixed amount of development, negatives exposed to different scenes which vary in SBR will have varying maximum densities.

Given a fixed SBR, negatives given different degrees of development, will also have different maximum densities.

A negative can be given more or less development, and this will affect the slope of the density curve as well as the maximum density.

Now, it is possible to record a longer SBR on the negative than can be printed on paper. Attempting to fit an extremely long-scale negative onto a normal grade of paper will result in the loss of shadow detail, highlight detail, or both.

Use of a lower-contrast grade of paper will result in flat-looking prints.

Reducing the degree of development and printing on a normal grade of paper will also produce flat-looking prints.

So, you have to choose what you want to preserve and what you can let go. You cannot capture it all in the print.

Special films and techniques have been employed to photograph nuclear explosions. Search for POTA.

https://www.digitaltruth.com/products/photoformulary_tech/Phenidone%20Extended%20Range%20Developer%20(POTA)%20[01-0070].pdf

 

[MattKing]

Technically, it isn't really Subject Brightness Range, or SBR, because that would properly only refer to the light emitted by subjects.
And equally technically, it should be Subject Luminance Range, or SLR, because luminance is a measurement of how much light reflects off a subject.
But SLR tends to confuse, and most use SBR anyways.
Photographic materials are designed to deal with the necessary compression of SLRs on to presentation materials not capable of duplicating the real life range of the world.
But they deal best with what might best be described as "average" subjects.
All the standards - ISO speed ratings for films, characteristic curve design for films, "standard" film development recommendations, contrast characteristics of photographic papers and printing equipment - all are designed to deal best with such "average" subjects.
If one's subjects fall outside the "average" range, there are manual interventions that can be used to deal with the situation, but they involve compromises, and are inherently more complex and difficult. Many of those interventions come at the printing (or post-processing) stage.

 

[Augustus Caesar]

Technically, it isn't really Subject Brightness Range, or SBR, because that would properly only refer to the light emitted by subjects.
And equally technically, it should be Subject Luminance Range, or SLR, because luminance is a measurement of how much light reflects off a subject.
But SLR tends to confuse, and most use SBR anyways.
Photographic materials are designed to deal with the necessary compression of SLRs on to presentation materials not capable of duplicating the real life range of the world.
But they deal best with what might best be described as "average" subjects.
All the standards - ISO speed ratings for films, characteristic curve design for films, "standard" film development recommendations, contrast characteristics of photographic papers and printing equipment - all are designed to deal best with such "average" subjects.
If one's subjects fall outside the "average" range, there are manual interventions that can be used to deal with the situation, but they involve compromises, and are inherently more complex and difficult. Many of those interventions come at the printing (or post-processing) stage.Yes, a print can never

Yes, a print can never come close to capturing the full range of a typical scene. Of course, a photo of a black cat in a coal mine taken in total darkness would be an exception. And of course, light emitted or reflected is still....light.

 

[MattKing]

Yes, a print can never come close to capturing the full range of a typical scene. Of course, a photo of a black cat in a coal mine taken in total darkness would be an exception. And of course, light emitted or reflected is still....light.

In some ways, a measure of a print's quality is how well it- the print - recreates the effect of real life "capture".
Our minds translate what we see in a print into a perception of range - sometimes incredibly effectively.
This digitized facsimile is of one of my prints that does that fairly effectively.

Objectively, I realize that the print doesn't physically have the same range as the original subject. But the subjective perception created by the print does emulate that range.

 

[Craig]

Very nice Matt, you have captured the elusive "luminescence" in the print. I have tried for years to get that and failed.

 

[Romanko]

There is no "dynamic range" in photography.

"High-dynamic-range photography" is a commonly accepted term. I believe we all understand that the dynamic range of the negative (or a print) is the range between the lowest and the highest density. Similarly, it could be used as a broader term for the Subject Luminance Range.

This digitized facsimile is of one of my prints that does that fairly effectively.

Great photo! Could you please share the technical details of this image (film, metering, developer, paper, etc)? It would be both instructive and relevant to the subject of this thread.

 

[SergioVileda]

Looking at these curves, paper is only able to represent 6-7 stops of SBR/SLR.
While film is able to capture 10 stops and compress them into same 6-7 stops of density.
If paper was able to capture same 10 stops of densities, then we would get completely different results on paper.

Wondering if it is possible to put some thick emulsion on top of the glass plate instead of paper, and print onto it, get same 10 stops of density, plus add some back illumination, emulsion need to be colorless.

 

[Romanko]

Wondering if it is possible to put some thick emulsion on top of the glass plate instead of paper, and print onto it, get same 10 stops of density, plus add some back illumination, emulsion need to be colorless.

This is totally possible. The medium is called slide. It is at least 100 years old.

 

[Lachlan Young]

Looking at these curves, paper is only able to represent 6-7 stops of SBR/SLR.
While film is able to capture 10 stops and compress them into same 6-7 stops of density.
If paper was able to capture same 10 stops of densities, then we would get completely different results on paper.
View attachment 366587

Wondering if it is possible to put some thick emulsion on top of the glass plate instead of paper, and print onto it, get same 10 stops of density, plus add some back illumination, emulsion need to be colorless.

I think you are seriously underestimating the amount of research (chemical and social) that went into defining the 'correct' exposure scales that deliver results that look good. Huge amounts of time, money and first-class scientific ability were expended on this, and what you are stating is indicative not of some great insight, but of limited understanding of the materials and how they relate to tone reproduction in a manner that looks perceptually pleasing to a randomised viewer.

 

[Romanko]

what you are stating is indicative not of some great insight, but of limited understanding of the materials and how they relate to tone reproduction in a manner that looks perceptually pleasing to a randomised viewer.

In-depth understanding starts with questions like these. @SergioVileda, you are on the right track.

Beyond the Zone System by Phil Davis

This is a great book that has answers to your questions, present and future.

 

[ic-racer]

Dynamic range of film is analogous to dynamic range of any other recording medium, like magnetic tape.

 

[MattKing]

Great photo! Could you please share the technical details of this image (film, metering, developer, paper, etc)? It would be both instructive and relevant to the subject of this thread.

It has been in the Gallery here since 2009

MSA Reflections - Ladner Boat Sheds

• MattKing
• Sep 20, 2009
• 8

At the water on a still, late summer evening

Some of the technical details are listed there.
I have made a number of different prints of it over the years. My current favorite is on Ilford Cooltone RC Glossy, and has the benefit of some sepia toning, which tends to cool the image tone even further. The most recent prints are also slightly lighter.
But most importantly, and perhaps most frustrating for those interested in technical details, I don't think its success depends a lot on those technical details.
The success comes mostly from the subject - its wide range of reflectance and the near glass-like water - and the nature of the light - direct and low in the sky, and slightly warm on a clear day. That and my visualization of the result.
I probably just used an incident meter reading, because my location on the shore was bathed in the same light as the boat sheds. I generally meter at or near box speed, and my development times are at or near manufacturer's recommendations. I think this was before I started using HC-110 replenished, but I'm not sure. In any event, the light, the subject and the lenses on that Koni-Omega (which I now regret selling) would have meant that I didn't stray from my "normal" development.
The image benefits from careful printing: just enough low contrast burn to give a hint of detail in the near specular highlights, just enough high contrast burn to deepen the shadows slightly, and just the right amount of moderate contrast overall printing to give the mid-tones the "snap" that rewards.
It is those factors that I mentioned earlier in this thread - the " ISO speed ratings for films, characteristic curve design for films, "standard" film development recommendations, contrast characteristics of photographic papers and printing equipment" - that function together to do most of the work necessary to allow realization of the initial vision.
The most important element in the printing process is and was being able to "see" in my mind the image I "saw" in my mind at the time of exposure.

 

[Augustus Caesar]

"High-dynamic-range photography" is a commonly accepted term. I believe we all understand that the dynamic range of the negative (or a print) is the range between the lowest and the highest density. Similarly, it could be used as a broader term for the Subject Luminance Range.

It could be, but it isn't. There are proper terms for these things, and it seems that learning when and how to use them would avoid confusion.

 

[Augustus Caesar]

In some subjective perception created by the print does emulate that range.

Yes, a print is an illusion in a sense.