Extended Characteristic Curve for Delta 100

andrew.roos · Apr 19, 2012

The Ilford Delta 100 datasheet only shows the characteristic curve up to a relative log exposure of 4. This is about 3 DU (10 stops) above the toe, or about 2.5 DU (8.3 stops) after the start of the straight line portion of the curve. The datasheet graph ends while still in the straight-line portion of the curve.

Does anyone have a characteristic curve for Delta 100 that shows what happens at higher exposures? Unfortunately I don't have a densometer to make my own measurements.

Thanks
Andrew

pstake · Apr 19, 2012

Michael R 1974 said:
Hi Andrew. I have curves for Delta 100 and I always plot to 14 stops above film base + fog, so that I can see what the shoulder looks like, particularly with reduced development. However I don't have access to them at work so I'd have to post tomorrow night if that is ok.

I'd be interested to see them, too.

john_s · Apr 19, 2012

I have the impression that the characteristic curves supplied by Ilford are a bit stylized and are "representative" of the films. Your post prompted me to have a look at the published curves, particularly since I'm looking for a replacement for Neopan400 (discontinued in 120 size). The published curve for 100Delta certainly shows a strong gradient without any sign of shoulder, vastly different to the curve for FP4+, although the two curves are for different developers for some reason.

Although it's not relevant to the OP's question (apologies) I found it interesting that the shapes are reversed for HP5+ and Delta400, the old emulsion having no shoulder and the new one some shoulder.

ic-racer · Apr 19, 2012

andrew.roos said:
The Ilford Delta 100 datasheet only shows the characteristic curve up to a relative log exposure of 4. This is about 3 DU (10 stops) above the toe, or about 2.5 DU (8.3 stops) after the start of the straight line portion of the curve. The datasheet graph ends while still in the straight-line portion of the curve.

Does anyone have a characteristic curve for Delta 100 that shows what happens at higher exposures? Unfortunately I don't have a densometer to make my own measurements.

Thanks
Andrew

That is about all you are going to get with the usual 21 step wedge.

andrew.roos · Apr 20, 2012

Michael R - Thanks, that will be wonderful. Your written description of the curve is also helpful.

john_s - Yes, I also looked at the other published curves and noticed this. I was wondering whether I could extrapolate from Delta 400 but decided this would not be sensible as the lower part of the two curves is somewhat different; and in any case, the faster film may have more layers with different light sensitivities, which would make extrapolation a bad idea.

ic_racer - Yes, but the problem is the positioning on the x axis. The plotted region from 0 to 1 DU is uninteresting (straight line at FB+F) on 100 speed films. It would be more useful to plot from 1 to 5 DU, which presumably could be accomplished with the same step wedge and illumination by giving a 1 DU increase in exposure. Of course the area from 0 to 1 DU is of interest for 400 speed films, which is presumably why it is shown.

Thanks everyone,
Andrew

Rudeofus · Apr 20, 2012

Check out (there was a url link here which no longer exists), I asked the same question a while back.

andrew.roos · Apr 20, 2012

Rudeofus said:
Check out (there was a url link here which no longer exists), I asked the same question a while back.

Thanks, your thread is interesting. It doesn't really answer the question of what does happen to the right of the published curves, though - of course we know there's a shoulder there, somewhere, but the question is "where?", which can only really be answered by measured data.

I suspect the reason why manufacturers don't publish the extended curve is because they assume that the user will be shooting at box ISO, developing normally and then producing a straight print. For this the published data is sufficient. But if one shoots with an EI lower than the box ISO, pulls development and then burns-in the highlights, then the extended portion of the curve does become relevant! Not that I usually plan to do this - but it would be nice to know what my options were, if the need arose; and how one should compromise with high contrast scenes (should one shoot box ISO to gain highlight coverage or is there sufficient latitude to shoot lower than box ISO and still get good highlight differentiation?).

Mahler_one · Apr 20, 2012

Interesting information Michael and thanks. Have you any data on film developed in one of the Pyro developers, and how the relevant curves might differ from the same film developed in a "non-Pyro" developer? Some of Sandy King's curves for films developed in PCHD show very little shouldering, e.g., take a look at HP5. Of course, the racer's comments about the 21 step wedge are relevant and one wonders how the curves would look if a 31 step wedge were to have been used.

Mahler_one · Apr 20, 2012

I took Rudeofus's suggestion and looked at the referenced discussion. Ron Mowrey's point about the extra density being difficult to print ( impossible? ) is to me quite relevant. If the added density cannot be routinely or easily printed on the materials on hand what relevance is the shoulder beyond the tonal scale of the paper? Would platinum printing be able to capture the increased highlights?

Mahler_one · Apr 20, 2012

Thanks for the examples and the interesting commentary.

As you no doubt are aware, those who use Azo papers feel that the tonal range is expanded beyond the range of more prosaic papers. I use Lodima and usually have little trouble rendering details in the highlights -which to some might appear "bullet proof" on the negative. Living and photographing in the Southeast makes high contrast scenes a common event. Have you had the opportunity to print some of your high contrast negatives on Azo or Lodima, and if so, would you care to comment about the tonal range of the paper and the characteristics of the print rendered as compared to your "regular" enlarging papers? Of course, Azo is a slow contact printing paper and cannot be used in the enlargers that most of us have. I know that Ron has authored a well received text on making Azo type emulsions; I wonder if he would care to comment about the "tonal range questions". Along with another photographer/investigator, we are using a 31 step wedge to try to compare the tonal range of various papers ( including Azo ) in order to furnish objective information about tonal range.

Chuck_P · Apr 21, 2012

Mahler_one said:
Interesting information Michael and thanks. Have you any data on film developed in one of the Pyro developers, and how the relevant curves might differ from the same film developed in a "non-Pyro" developer? Some of Sandy King's curves for films developed in PCHD show very little shouldering, e.g., take a look at HP5. Of course, the racer's comments about the 21 step wedge are relevant and one wonders how the curves would look if a 31 step wedge were to have been used.

Each step of a 21-step tablet is equal 0.15 (1/2 of a stop), each step of a 31-step tablet is equal to 0.10 (1/3 of a stop) and each step of a 41-step tablet is equal to .05 (1/6 of a stop). Having more steps only ensures more data between each stop, it doesn't mean, IMO, that you get extended curve data. Each of the step tablets will provide, if I'm not mistaken, 10 stops worth of data. So, a curve drawn using a 41-step tablet versus using a 21-step tablet will only prove to be somewhat more precise when it comes to drawing the curve between the stops, zones, whatever designation you choose----tantamount to connecting the dots with much shorter lines with a 41-step versus longer lines with a 21-step tablet.

andrew.roos · Apr 21, 2012

Michael R 1974 said:
Back to the original request, attached are a few curves for Delta 100 in two general purpose developers. On the graph, "M" on the x-axis is the metered exposure (zone V), and the units are stops. In zone system terms the graph plots from zone zero to zone XV. However I no longer use that convention on the x-axis, following some very interesting discussions with Stephen Benskin regarding things like flare (this graph represents a low flare test, but that is not really relevant where the shoulder is concerned). The y-axis is the net density above film base+fog.

The film in this case was 35mm, rated at box speed and developed to normal contrast for condenser enlarging (approximately N-1 for diffusion) using a normal agitation scheme consisting of 1 minute initial agitation, followed by 10 seconds agitation at the beginning of each subsequent minute. Development time at 20C was 8 minutes in DDX 1+4, 9 minutes in XTOL 1+1.

Comparing different films' curves is often more interesting, but since the request was specifically for Delta 100 I figured this would be a useful start.

Thanks Michael. That's precisely what I was looking for!
The difference between XTOL and DDX is also very intesting.

Andrew

Mahler_one · Apr 21, 2012

Thanks Michael. If you want to see a very interesting film curve, take a look here:

http://unblinkingeye.com/Articles/PCat/PCat4/pcat4.html

Move down to the graphs for enlarging papers ( blue I believe ), and look at the curves for Tmax and HP5 in PCHD. I often use HP5 and I have not found the abrupt shouldering that others have reported. I sometimes wonder if information is simply repeated by successive posts and in successive articles; such information gets a "life of its own" by being quoted over and over again-when in effect, many of those who quote information about HP5 and other photographic subjects have never carried out their own tests or even used the materials in question. A thread for another time....:}

Regarding your curves for DDX...a great developer that is underrated and unfortunately, is thought of as not being very "sexy". I use the developer at either 1:9 or 1:11, and with sheet film, DDX is excellent AND quite economical at the dilutions indicated. Interesting when one notes the HP5 in DDX and in Xtol. Michael: The curves for sheet film and roll film of the same name can often be quite different.

ic-racer · Apr 21, 2012

You could sandwich a strip of 3.0 log D (10 stop) neutral density filter along half of a 21-step wedge and still be able to read the boxes with a standard 3mm densitometer probe. But then you have the issue that a calibrated sensitometer won't be able to blast that with enough light to get a good curve. Because the toe is now going to be on the super-dense part of the step wedge.

If you are just contact printing the step wedge under a lightbulb to see the shape of the curve, the above-mentioned modification should work.

Maybe Michael R 1974 will tell us if he used a similar method.

andrew.roos · Apr 22, 2012

Michael R 1974 said:
Glad this was helpful. Of course one can change the shape of the curve with different development procedures, even using the same developers. But these curves give a reasonable baseline with respect to the film's inherent gradation characteristics. Although I didn't post them, the shape is very similar when using ID11/D76 and other developers under normal circumstances. In the end, as I said earlier most current films from Ilford and Kodak have similar characteristic curves. Acros is an exception, with a longer straight line and more abrupt shoulder.

Thanks this is good to know as I use ID-11. If you happen to have those ID-11/D-76 curves handy, I would love to see them too....

Thanks again,
Andrew

Mahler_one · Apr 22, 2012

Thanks Michael. Appreciate the information. As they say....if the method you use yields the results that you desire, don't change!

I agree about today's films being reasonably similar. Good point about the variability in staining as influencing the character of a particular film used with a particular staining developer. The only time I use a staining developer is when I want to develop by inspection, i.e., not very often! Otherwise, for me using DDX on the Jobo CPP2 with the expert tanks, and implementing development as determined by BTZS methods, yields consistent and reproducible results. And to repeat, using the greater dilutions makes DDX very reasonably priced.

Let me know if you are ever in Northern Florida. The door is always open for wine and shop talk!

DREW WILEY · Apr 23, 2012

I completely disagree with one of your assertions, Micahel, that these various films are more or less homogenous
in terms of curve characteristics. If that was the case, why would they eveb bother making different ones in similar
speeds. Delta 100, for example, has a long sweeping toe, whereas FP4 is steeper in the toe. HP5 is somewhere
in between. This has a dramatic effect on how the shadows are reproduced as well as actual film speed in realtion to a scene. Each of these films has a very different personality, really. And unless one is working with a
low contrast scene where only the straight line is usable, simply altering dev times will not change the formula.
None of the Ilford film are real straight-line films, though FP4 is the closest. And the question is not how far up
the curve on can hypothetically go, but what the usable part of the curve is relative to scene illumination and
one's expectation of tonal separation.

DREW WILEY · Apr 23, 2012

Well I did just look it up, and it seems Delta 100 hasn't changed since I last used it, and my densitometer sheets are way more detailed anyway; and it is a dramatically different film per the low
zones than TMX100, which will separate at least two zones lower given analagous development. So
what this means is that if you want to use the staight line of this - in fact long-toe film - is that
you need to expose it around ASA25 and risk the neg density building up till its an issue itself. It's
a nice film for silvery midtones and highlights, so essentially a modern replacement for Plus X Pan
with finer grain. No resemblance to any TMax products, which have high contrast in the toe.

DREW WILEY · Apr 24, 2012

Wow. Are we even shooting this stuff on the same planet????????? Try plotting your own curves.
Or get up into the high mtns, or harsh desert light, or here in the redwoods with huge contrast
ranges. Then tell me how Delta 100 works. I'm not calling it a bad film. Lots of people like it. But
TMX it ain't - and even that has real problems holding both shadow detail and highlights in extreme
scenes. Or try a real tricky application like making color separation negs. TMx works wonderfully,
Delta 100 would be nearly useless, FP4 reasonably well - even Ilford states as much if you read
the fine print.

DREW WILEY · Apr 24, 2012

I'm trying to figure out where you're coming from, Michael. Is Perceptol your usual developer? That
is something high-sulfite semi-compensating, which builds a toe. Have you tested TMX in HC-110,
TMRS or the various pyro formulas better matched to the potential scale?

andrew.roos · Apr 24, 2012

Interesting discussion. I would still love to see the curve for D100 in D-76/ID-11 if available and when convenient.

Thanks!
Andrew

DREW WILEY · Apr 24, 2012

I've always gotten full speed out of TMX no problem. The bigger risk with TMX is shouldering with
overexp. But it's not my favorite film in the field - more of a lab and studio standby. I prefer true
straight line film like the now disc Berrger 200, old Super XX, or now TMY400 (not quite straight-line
but fairly close). Or in small format Efke 25. I'd never get similar shadow sep with Delta, FP4, HP5.
That bottom part of the curve is critical. #76 puts a sag in the curve. HC-110 better. TMRS even
straighter. But for general shooting, Pyro has spoiled me and I've never looked back. On my last trip
up high I chose a roll film back due to the wild weather (to keep bellow ext shorter in wind) - took
three of the 25's - Efke, Pan F, and Rollei - comparison prints show huge differences in the shadows,
even though I consider myself fairly expert in use of these films. What looks best is of course related
to the specific subject and its luminance range. With the very short straight line of Pan F you want
slightly subdued lighting, much like exposing color film. Rollei a bit longer scale, and then Efke, which
will handle 12 stops without resorting the minus dev. High altitude really is an acid test, esp with a
red filter involved (though Efke is technically orthopan, rather than typical pan).

DREW WILEY · Apr 24, 2012

Oh - if you ask why I chose slow speed film roll film at short extensions vs faster sheet film it's that
most of the windy shots were on top passes etc where much of the subject was at inifinity, therefore relatively wide aperture and short exp possible, even with slow film. Most of the close-up
shots were down in the canyon where wind was less an issue. But it was an informative experiment
anyway, even though I basically already anticipated the result. To me, when it comes to curve
shape, ACROS is between Delta 100 and FP4, but with different spectral response (it's orthopan too)
But ACROS is about the most similar film to Delta currently in production, at least in curve response
and effective film speed. I'm not stating this to be argumentative. If anything, I'm a bit like a kid
in a candy shop because there are so many good choices out there, and you can't carry them all
at the same time!

Sal Santamaura · Apr 24, 2012

Michael R 1974 said:
...The "standard" developers I've tested the films in are...and XTOL...I don't have access to my film tests here at work, but at home I can post...

Michael, if you have Delta 100 in XTOL 1+3 among those data at home, I'd really appreciate seeing the curve. Thanks in advance!

DREW WILEY · Apr 24, 2012

For general subject matter I prefer various tweaks of PMK. I do tray or manual drum dev, and its an
extremely verstatile dev. But I've experimented with all kinds of dev, and keep quite a few on hand
for specialized lab applications. Mtn or high desert lighting can give shadows remarkable depth and
crispness and really separate the men from the boys in terms of film toe. Around here on the coast
we get a lot of fog, and a film with excellent highlt separation like Delta might do quite well (though
for 8X10 I prefer the speed and edge effect of HP5) - then when the fog breaks, the rules of the
game change completely, esp in the redwoods. So it's not unusual for me to carry two different types of b&w film on the same day. TMY400 comes about as close to the silver bullet as anything
I've found. Some of the carbon printers even use Efke 25 in sheet film because of its incredible range
in strong lighting. Very different than minus dev, which sacrifices midtone microtonality. Studio use
is completely different because the lighting ratios can be controlled. But often we do get almost
natural "softbox" conditions in the fog, where a longer toe film can be used to plus dev the midtones
and highs. I esp like doing that with HP5, but then might have to reign in the extremes with a mask,
even with VC papers. Lots of fun tricks out there!

Extended Characteristic Curve for Delta 100

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