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

[Augustus Caesar]

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.

Yes, something transilluminated. Dupont used to coat Varilour B+W emuslion onto an opalenscent polyester material; the brand name was Cronapaque. It was milky white, and the surface was matte. I used quite a lot of it. I have asked Ilford to bring out something similar, but they have not replied.

 

[pentaxuser]

I gradually increased development time up to +170%, and found that dynamic range goes up to 9,5 stops.

What was the negative like at that development time? Pretty bulletproof I'd have thought but it seems that it had improved it in terms of capturing what range of tones it was able to capture so did this improve the print compared to the print that was developed for the "Ilford" time?

Thanks

pentaxuser

 

[Augustus Caesar]

What was the negative like at that development time? Pretty bulletproof I'd have thought but it seems that it had improved it in terms of capturing what range of tones it was able to capture so did this improve the print compared to the print that was developed for the "Ilford" time?


Thanks

pentaxuser

No, the degree of development does not affect the latitude of the film. It merely affects the slope of the curve.

 

[pentaxuser]

No, the degree of development does not affect the latitude of the film. It merely affects the slope of the curve.

Can you explain what your quote above translates into when it comes to making a print from what sounds to be a grossly overdeveloped negative

Thanks

pentaxuser

 

[Craig]

Can you explain what your quote above translates into when it comes to making a print from waht sounds to be a grossly overdeveloped negative

Thanks

pentaxuser

Slope of the curve is the contrast. As development increases, the slope steepens, which means the contrast increases. The end points of the curve in terms of the minimum amount of light the film can record and the maximum black that the film can generate do not change.

In Zone system terms, that is what you would do for taking a very flat scene ( such as fog or heavy overcast) with a small subject brightness range and expanding it to a more normal contrast range in a print. A very useful tool, if you know how to use it.

 

[pentaxuser]

Thanks Craig. The example you gave is a fairly "extreme" light situation which in effect you are trying rectify but in normal light conditions or controlled light conditions as the OP had what if any are the detrimental effects of a grossly over exposed negative such as I assume the OP's to be at the kind of overexposure he mentions. He states his dynamic range increased and this sounds a good thing but assuming this was the case then what if any are the "downsides" in terms of making a good print

Even for the situation you describe in which over development is needed +170% still seems a lot but what I wanted to know from the OP was what his negative looked like in normal light conditions and overdeveloped by +170% he found his dynamic range had increased quite markedly but I just wondered whether his print from such a negative looked in any way normal and was easy to print?

If it was and was indistinguishable from one printed at Ilford recommended time except for its markedly increased dynamic range then that a recommendation/ endorsement for using at least twice the recommended Ilford time for all of us and ignoring recommended times , isn't it?

Maybe Augustus Caesar will say the same as you in terms of his clarification but I don't yet know as he hasn't yet responded

pentaxuser

 

[Augustus Caesar]

Can you explain what your quote above translates into when it comes to making a print from what sounds to be a grossly overdeveloped negative

Thanks

pentaxuser

The latitude of the film is inherent in it. It has nothing to do with development. Grossly overdeveloped negatives can be reduced chemically.

 

[SergioVileda]

Thanks Craig. The example you gave is a fairly "extreme" light situation which in effect you are trying rectify but in normal light conditions or controlled light conditions as the OP had what if any are the detrimental effects of a grossly over exposed negative such as I assume the OP's to be at the kind of overexposure he mentions. He states his dynamic range increased and this sounds a good thing but assuming this was the case then what if any are the "downsides" in terms of making a good print

Even for the situation you describe in which over development is needed +170% still seems a lot but what I wanted to know from the OP was what his negative looked like in normal light conditions and overdeveloped by +170% he found his dynamic range had increased quite markedly but I just wondered whether his print from such a negative looked in any way normal and was easy to print?

If it was and was indistinguishable from one printed at Ilford recommended time except for its markedly increased dynamic range then that a recommendation/ endorsement for using at least twice the recommended Ilford time for all of us and ignoring recommended times , isn't it?

Maybe Augustus Caesar will say the same as you in terms of his clarification but I don't yet know as he hasn't yet responded

pentaxuser

Hello guys,

unfortunately I did not try print from 0% and 170% negatives.
I was investigating do I expose negatives correctly.
I thought when I correctly expose and develop the negative, I should get 10 stops of density on the negative.
But that was wrong assumption.
Film manufacturer provides development times with printing on paper as ultimate goal.

What is happening during development, that subject brightness/luminance, let's assume 10stops is being compressed into 5-6 stops of density on negative.
My understanding is that is done intentionally, to then fit this 5-6 stops of film densities into 6-7 at most stops of paper exposure that paper is able to accept.
After paper is developed, it will render only 10^2 ~ 6-7 stops of densities.

So, original 10stops scene, will be compressed into 6.5 stops at best on paper.

If our goal is not to print o paper, but only to scan the negatives.
Then, I think, a different times should be used.
What development time shall be used?
The one that provides contrast close to 1.

from this graph, to get maximum density range on the neagive = 10 stops,
time shall be around 16 minutes, instead of recommended 8 minutes.
Because recommended time is good for printing on paper, but not for scanning.

 

[koraks]

let's assume 10stops is being compressed into 5-6 stops of density on negative.

Given a target gamma of 0.6 or 0.65 or so, that sounds about right.

After paper is developed, it will render only 10^2 ~ 6-7 stops of densities.

Yeah, best case scenario, with the caveat that what happens in the murky shadows needs a lot of contrast for the human eye to make much out of. Also, on matte paper, the reflective density is more like 1.6logD or so, which means 5-5.5 stops of dynamic range.

If our goal is not to print o paper, but only to scan the negatives.
Then, I think, a different times should be used.
What development time shall be used?
The one that provides contrast close to 1.

That sounds totally arbitrary. Why?

When optimizing for scanning, you would typically approach the matter from a signal-to-noise ratio angle, optimizing for the cleanest possible signal, preferably across the entire dynamic range of the negative. Mind you, that's a very technical base assumption to make and has nothing to do with artistic expression etc., which often ends up optimizing in an entirely different direction. Having said that, if you consider s/n ratio, you will start balancing the following aspects, mostly:
* Sensor linearity
* Sensor noise
* Interference artefacts between sensor system and film/grain structure
You will end up compromising between these factors, which also depends on strengths and weaknesses of the scanning system.

To save you a lot of time and effort trying to figure all that out, it turns out that in practice, scanners are quite good at getting a surprisingly clean and usable signal from relatively thin negatives. On the other hand, especially when scanning B&W negatives, they tend to to rather ugly things with high density (in the negative) highlights, since linearity tends to break down, grain gets emphasized etc. The takeaway of this is that when optimizing for scanning, you generally develop for a relatively low gamma. However, scanners are fortunately generally quite good at dealing with negatives that also print well on grade 2 or so, which means that you can safely rely on the suggested development times by the manufacturer for normal contrast.

TL;DR - save yourself a lot of trouble and just do as Ilford/Kodak/etc. says. It'll work out fine that way, also if you scan instead of enlarge your negatives.

 

[Lachlan Young]

If our goal is not to print o paper, but only to scan the negatives.
Then, I think, a different times should be used.
What development time shall be used?
The one that provides contrast close to 1.

No. What you are failing to understand is that modifying development time changes the gradient and length of the straight-line part of the curve. More development steepens and shortens the straight line (and sharpens the toe/ shoulder transitions), less development lowers the gradient and lengthens the straight line (and softens the toe/ shoulder transitions). Too much of a reduction in development will give you flat mid-tones, even if it has nominally squeezed more information on to the straight line.

I'll give you some clues: 0.35-0.4 and (more realistically) 0.5. Once you get how those numbers are arrived at, then you will understand that you aren't on the cusp of some great discovery, but merely learning (the very hard way) how these materials work.

And compromising negatives for scanning is almost never a good idea. Any decently competent scanning solution (not a consumer flatbed generally) can handle the density range of even seemingly dense negs.

 

[koraks]

Any decently competent scanning solution (not a consumer flatbed generally)

A consumer flatbed will perform quite well with B&W negatives that are developed to print well on grade 2. What they generally struggle with is very high densities, which means slide film and overdeveloped B&W film. This is one of the reasons why it's not a good idea to develop B&W for a gamma of around 1, since it'll create high densities in the highlights which will render particularly ugly when scanned on a consumer flatbed. Densities up to 1.8logD or so generally scan quite well even on modest scanners.

 

[Lachlan Young]

A consumer flatbed will perform quite well with B&W negatives that are developed to print well on grade 2. What they generally struggle with is very high densities, which means slide film and overdeveloped B&W film. This is one of the reasons why it's not a good idea to develop B&W for a gamma of around 1, since it'll create high densities in the highlights which will render particularly ugly when scanned on a consumer flatbed. Densities up to 1.8logD or so generally scan quite well even on modest scanners.

They struggle a bit less in terms of density handling with larger film - but either way, they aren't good in terms of sharpness, contrast, noise, colour etc - especially not against the many similarly priced options today.

Either way, as you know, there are applications where a gamma of 1.0 is needed, but the reasons outlined on this thread aren't them.

 

[koraks]

Either way, as you know, there are applications where a gamma of 1.0 is needed, but the reasons outlined on this thread aren't them.

Certainly; I go beyond this, routinely, and habitually intensify negatives to boost gamma even further. But this is only for contact printing; these negatives don't work anymore for silver gelatin printing, nor do they scan well. In fact, they're virtually useless apart from their intended purpose, which is carbon transfer printing. It's a very specific application where the density scale needs to be taken to extremes.

 

[Bill Burk]

When you said 18 minutes D-76 stock, you caught my attention. That should give you a very high contrast index near 1.0.

You mention a ten stop grayscale test pattern.

I bet it reflects a five stop subject luminance range and you see a graph that looks near 0.5 contrast index because you reproduced the original. One to one.

Take an exposure meter reading of the tones of your test target from black to white and you will find that the difference in readings is only five stops.

Now you can use your test pattern in another way to get closer to ten stops.

Based on your meter readings, circle the steps on your pattern which read on the meter half stop and one stop apart. It might be every other patch, or it might skip around.

Test with two exposures, one that is three stops less than the other. Develop and read the circled patches and you will find development time less than 12 minutes in D-76 stock matches close to your 18 minutes.

 

[Bill Burk]

Now you need not re-do all your tests to see what I mean.

Change the exposure axis.

Make it agree with exposure meter readings of the test pattern. Then reinterpret the graphs.

You will probably find at most five stops difference (probably 4 2/3 stop) between whitest white and blackest black. On your exposure meter looking at patches of the test pattern.

You should find the ten steps that you thought were a whole stop apart are actually closer to a half stop apart.

 

[Bill Burk]

Here’s a test target and a silver gelatin print of it in a scene with my dog, “Winter” (malamute/husky). The white stripe has reflection density 0.04 and black is 1.44. The difference if you read with an exposure meter is 4 2/3 stop. (Target subject luminance range 1.4 divided by 0.3 density difference for a stop equals 4 2/3 stops).

The full subject has more luminance range than the target because there’s shadows in the three dimensional scene that can be darker than an evenly-illuminated two-dimensional target. I might have included sky or chrome reflections that could have increased luminance range in the brighter end of the scale.

A normal scene, prints a realistic optical illusion of a target that goes white to black even though the target does not print white to black on the print.

 

[Bill Burk]

@SergioVileda the reason your ten step graph looks normal is that you have distorted the log exposure axis of your graph.

Rescale the graph so that the labeled 0 to 10 steps span across 1.4 log exposure units and keep the density axis as-is.

Then the exposure and density will have the same scale and you will see how steep your curves really are.

 

[Bill Burk]

I may have mischaracterized your test method as a reflection target like this which is limited to 5 stops. Stouffer’s cameraman’s sensitivity guide is nominally 5 1/2 stops.

 

[Bill Burk]

Your test sounds more like this: a light box with a Stouffer scale that you take close-up photos of.

 

[Bill Burk]

I once did a study of the “Stouffer scale taped to a window” where I estimated and factored out 0.4 flare for Rafal Lukawiecki of Tri-X 320 in Xtol 1:1

This distorted log exposure axis scale is a fair approximation of what comes about from taping a transparent scale to a window (or light box) and shooting it.

Flare distorts the results and if you use a logarithmic scale for exposure axis you will have “depressed” contrast interpretations…

That could lead you to think 18 minutes in stock is normal.

 

[Lachlan Young]

Then the exposure and density will have the same scale and you will see how steep your curves really are.

Your test sounds more like this: a light box with a Stouffer scale that you take close-up photos of.

This is probably the most likely explanation - it seems to have been a fairly well known fault in the past, common to those who acquired densitometers without essential basic contextual sensitometric knowledge (which more start with today - and which is why there assumptions of the correct procedures being followed by others who responded to this thread).

 

[DREW WILEY]

HP5 has a somewhat long toe. Therefore, unless it's a moderate contrast scene, you'll want to boost shadow gradation by shooting it at lower than box speed. You might try 320 instead of 400.

Step tablet tests are a valid starting point, but don't tell the full story. I don't have time to explain it here. A lot has to do with the specific developer of course. But D76 does tend to put a bit of sag in the curve, further accentuating the toe, especially in "minus" development situations.

Short story - HP5 is not the best film for high contrast situations. And I've developed and printed HP5 for decades, especially in relation to 8x10 film, where errors in this respect can get painfully expensive. I never rely on the alleged "latitude" of a film. Light meters were invented for a reason.

 

[Augustus Caesar]

HP5 has a somewhat long toe. Therefore, unless it's a moderate contrast scene, you'll want to boost shadow gradation by shooting it at lower than box speed. You might try 320 instead of 400.

Step tablet tests are a valid starting point, but don't tell the full story. I don't have time to explain it here. A lot has to do with the specific developer of course. But D76 does tend to put a bit of sag in the curve, further accentuating the toe, especially in "minus" development situations.

Short story - HP5 is not the best film for high contrast situations. And I've developed and printed HP5 for decades, especially in relation to 8x10 film, where errors in this respect can get painfully expensive. I never rely on the alleged "latitude" of a film. Light meters were invented for a reason.

HP5+ should be better than TXP 320 for high-contrast situations.

 

[Bill Burk]

Drew, in all your experience have you developed HP5 for 18 minutes in stock D-76? Would you agree that would not create a normal negative?

 

[Lachlan Young]

Drew, in all your experience have you developed HP5 for 18 minutes in stock D-76? Would you agree that would not create a normal negative?

I don't think he's ever done any sensitometry of HP5+ in anything, never mind D-76/ ID-11. If he did, he'd know that it doesn't have any 'sag' in the midtones and that the toe is exactly as sharp as Tmax 400 or 400TX.