T-Max 400 has boomerang curve

albada · Mar 16, 2013

As part of testing a new developer I've created (in "Progress on XTOL-concentrate" thread), I've been testing and plotting all films made by the big three makers. T-Max 400 has this interesting curve:

It's shaped like a boomerang, and that will cause highlights to block up sooner. If you're spending much time burning-in your highlights with T-Max 400, this might be why. For comparison, here are curves for HP5+:

Once past the toe, HP5+ marches in a straight line like a soldier. This also shows that my own test equipment and methods aren't producing that boomerang curve. I saw this issue with T-Max 400 a few months ago, but I blamed my own testing. But results with other films show that my tests are okay. Interestingly, Tri-X also makes a boomerang:

But the boomerang for Tri-X is facing up instead of down, and the change in angle is small. It'll give you a bit of compression (compensation) in the highlights.

T-Max 400 worries me. In a prior posting, PE said this means that Kodak is having trouble blending emulsions correctly. I think T-Max 400 has two emulsions. Hold a piece of paper against the monitor to use as a straightedge, and you'll see that the curve consists of two straight lines. I suspect their slopes are supposed to be the same.

Mark Overton

jp498 · Mar 16, 2013

My highlights are awesome with tmax 400; never have to burn them in. I use pyrocat HD or PMK and develop in patterson tanks or combiplan tanks. What you haven't mentioned is your agitation scheme? Rotary processing? Tank? Developer and dilution? Lots of things can change results to be different than what you've posted. It's a versatile film, and "responsive to changes in development".

Rudeofus · Mar 16, 2013

Is there a chance that these TMAX 400 curves straighten out somewhat if you dilute your developer?

Photo Engineer · Mar 16, 2013

I'm surprised by those curves. They look nothing like the data I have seen. Something is wrong with the film or the process (agitation?) or whatever.

I would check it out with other options and then contact EK if this persists.

PE

albada · Mar 16, 2013

Further info about my process:

I agitate using Fuji's method: Once per minute.
I'm using a stainless steel single-reel tank with 200-210 ml of developer (barely covers the film).
XTOL was used stock (not diluted).
The T-Max 400 is batch number 0167 bought a few weeks ago and kept frozen, and the XTOL was mixed last week. So everything is fresh.

Regarding more dilution: The concentrates shown in those curves are similar to XTOL diluted 1+1, so I doubt dilution makes a difference.

Regarding agitation: The concentrates take about twice as long to develop, so they'll get twice as many agitations as XTOL. Since they develop at half the rate of XTOL, the behavior of the concentrates should be similar to agitating XTOL twice per minute. Yet the curves are identical. I'm curious to see what curves Michael R gets...

Mark Overton

Photo Engineer · Mar 16, 2013

I would contact EK. This looks like too little fast component or a keeping problem.

PE

albada · Mar 17, 2013

A few more notes:

In both graphs for T-Max 400, I waited 23 hours between exposure and development. Films have different latent image keeping (LIK) characteristics, and the delay was to simulate real-life usage. I suppose it's conceivable that the two or more emulsions in T-Max 400 could have different LIK decay-rates, so the curve could change based on exposure-to-development delay.

This boomerang is a form of upsweep. In the thread on "Kodak Tri-X- D76 vs HC110 Dilution B (upswept curve look?)", Bill Burk says he believes that upsweep helps portraiture by improving tone-separation in faces. I didn't think of that. I was thinking more of what upsweep would do to sky and clouds.

jp498 said "My highlights are awesome". There are a number of possibilities, one of which is that I goofed. Or you might be using a different batch of TMY2. Or maybe TMY2 with pyrocat or PMK produces a straighter curve. Do you have a Stouffer step-wedge? It would be interesting to get the curve.

Anyway, I exposed a new roll last night, and I'll let it age (LIK) and decide what to do with it once Michael R's results are in.
Michael: If you post or PM your densities to me, I can plot them using my gnuplot script.

Mark Overton

noacronym · Mar 17, 2013

I never liked Kodak dropping the Plus-X, Verichrome Pan, and Tri-X for this T-max stuff. Never liked it. If it's not broke, don't fix it.

AndreasT · Mar 17, 2013

My curves using X-tol 1+1 are similar. I just have a hump which goes up in the lower half. I would say I also have two curves in one but the upswept part is relatively high up so if one doesn't over expose too much it should still be fine.
Checking my other developers they nearly all have this hump. Different but somewhere to be found.

john_s · Mar 17, 2013

I think I remember reading that the upswept curve was favored by studio photographers. But they have control of lighting that we landscape photographers don't have.

albada · Mar 17, 2013

Michael R 1974 said:
Well, my first test won't be of any use. I hadn't used TMY2 with XTOL before, and hadn't used XTOL at stock strength before so I went with Kodak's recommended time of 6:30 @ 68F (which seemed very short) and Kodak's agitation recommendation. Way underdeveloped. I got the equivalent of N-3. I suppose I should have expected this since my TMX times with XTOL 1+1 are significantly longer than Kodak's.

The shape of the curve did resemble Mark's upsweep, but with this degree of underdevelopment I can't come to meaningful conclusions regarding TMY2's normal curve shape in XTOL so I will have to redo this at least one more time.

By the way my rolls are from the same batch as Mark posted.

Apologies.

Michael, I suspect something went wrong. I develop TMY2 the same way you did: XTOL (stock) at 6:30 @ 68F, but agitating less than you, and I get normal density and a normal CI of 0.57. What's the density of your leader? Mine is 2.76, which is higher than most films.

YIKES! I just remembered another detail: I always pre-soak the film! I discovered a year ago that TMY2 gives higher densities when pre-soaked. I give it 4 minutes agitating twice per minute. Sorry, I should have mentioned this earlier. But even so, the lack of a pre-soak should not cause an N-3 pull.

Anyway, your test is probably useful because I've noticed that under/overdevelopment does not change the shapes of curves much. Could you post your numbers or graph? BTW, thanks for doing these tests!

Mark

albada · Mar 18, 2013

Michael R 1974 said:
That is disturbing to say the least. I have always needed significantly longer times than Kodak recommends for XTOL/TMax films, and my times have always been consistent. I have no explanation for this. Perhaps someone else should run the tests.

In addition to a pre-soak, here are a couple more ideas:

* Inaccurate thermometer (are all times longer than expected?).
* Something in tap-water damages XTOL. (BTW, I use distilled water because my tap-water is hard).

If you don't mind running another test, you could do so using your times and process that are known to work. But AndreasT and you have already reported upswept curves, so maybe we already know what the result of another test would be...

Mark

DREW WILEY · Mar 18, 2013

Tmax gets the straightest curve with TMRS developer. But TMX can shoulder off if overexposed in full range lighting; and that's a reason it should not be rated below box speed with certain common developers. Some developers will create an upswept curve at the top with TMY, but you've really got to
be up there where you don't belong to begin with. I've used a variety of developers with these films, but never XTol - and if Xtol does in fact predictably produce a toe like that, I wouldn't even want to
bother with it.

albada · Mar 18, 2013

Michael R 1974 said:
Thermometer is certified/calibrated, and I use distilled water for all chems. XTOL/TMax films is the only combo for which my times are long (regardless of dilution - stock, 1+1, 1+3). Curiously with Delta 100 my times are pretty close to Kodak's, and that's with less agitation than Kodak. Very strange. I will redo but I'm sure I'll get the same results as my process is tightly controlled. Perhaps I exposed incorrectly.

Do the edge-markings look thin? If so, your exposure is probably fine. Anyway, it would be interesting to re-try the process with an added pre-soak and/or longer time.

DREW WILEY said:
Tmax gets the straightest curve with TMRS developer. But TMX can shoulder off if overexposed in full range lighting; and that's a reason it should not be rated below box speed with certain common developers. Some developers will create an upswept curve at the top with TMY, but you've really got to
be up there where you don't belong to begin with. I've used a variety of developers with these films, but never XTol - and if Xtol does in fact predictably produce a toe like that, I wouldn't even want to
bother with it.

Drew, you bring up some interesting points. (1) Like you, I've seen TMX shoulder-off and also recommend that it not be overexposed. But my latest concentrate makes it shoulder-off too soon, so I'm wondering whether to do anything about that. (2) My TMY2 curves in the OP shows the upsweep starting in the upper midtones or low highlights, so it'll affect folks (assuming it's not due to my own goof). Maybe it started farther out in prior batches. (3) The toe of TMY2 looks sharper than most to me; what about it do you dislike?

Mark Overton

StoneNYC · Mar 18, 2013

So, how do you guys measure this stuff? Like can you explain the process if messing a curve? Do you scan it with a special program or how do you plot it?

Thanks.

~Stone

Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk

brucemuir · Mar 18, 2013

Stone,
Google densitometer.
Its a machine that measures silver densities directly off the film.

Photo Engineer · Mar 18, 2013

Guys;

We had this problem at EK. We had standards committees for all work so that all things were as equal as possible!

PE

DREW WILEY · Mar 18, 2013

I use the same standard ole Kodak plotting paper that I've used for decades. No fancy programs. Just
a densitometer and a sharp pencil. It's translucent, so one can directly compare curves over a lightbox.

AndreasT · Mar 18, 2013

I just double checked some of my results. All from the same batch. Basically all TMY curves in my results do tend to be upswept.
Except with FX-39.

Mr Bill · Mar 18, 2013

StoneNYC said:
So, how do you guys measure this stuff? Like can you explain the process if messing a curve? Do you scan it with a special program or how do you plot it?

The normal method is to start by exposing a piece of film through a commercial step wedge. The wedge is typically a piece of B&W film, with each step getting successively darker, by a specified amount. So you essentially have made a single exposure, but it contains a very wide range of light intensities. A common style of wedge covers a 10 f-stop range in 21 steps.

After developing, you measure each step on your film with a transmission densitometer, which is essentially a light meter for the darkness of film. It reports this as "optical density," thus the name densitometer.

Finally, you plot each step on a graph. For the scales, the exposure is normally done in log units; typically the amateur doesn't know the exact power of the light source, so they just use the relative values. The other scale is the film density. This is basically the same thing as the published "characteristic curves" for film.

Since about the mid-1980s, nearly all densitometers have a computer interface, at least as an option, so if you have a proper program, you can collect the numbers automatically. It's easy enough to make graphs using a computer spreadsheet. Or just bypass the graph and calculate what you want directly.

StoneNYC · Mar 18, 2013

Mr Bill said:
The normal method is to start by exposing a piece of film through a commercial step wedge. The wedge is typically a piece of B&W film, with each step getting successively darker, by a specified amount. So you essentially have made a single exposure, but it contains a very wide range of light intensities. A common style of wedge covers a 10 f-stop range in 21 steps.

After developing, you measure each step on your film with a transmission densitometer, which is essentially a light meter for the darkness of film. It reports this as "optical density," thus the name densitometer.

Finally, you plot each step on a graph. For the scales, the exposure is normally done in log units; typically the amateur doesn't know the exact power of the light source, so they just use the relative values. The other scale is the film density. This is basically the same thing as the published "characteristic curves" for film.

Since about the mid-1980s, nearly all densitometers have a computer interface, at least as an option, so if you have a proper program, you can collect the numbers automatically. It's easy enough to make graphs using a computer spreadsheet. Or just bypass the graph and calculate what you want directly.

Oh that description was perfect for my kind of brain, now I understand what the heck everyone is talking about (sort of) so the tow and tail are the highlight and blacks? So why does the upswept whatever mean, I didn't see a boomerang shape at all when I looked at the first OP's graph so I was totally confused (still am) so anyway this at least gets me a little more understanding.

I was thinking this was done on any normal picture (I was going to ask if I could use my most recent uploaded image haha).

Thanks.

~Stone

Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk

Mr Bill · Mar 19, 2013

StoneNYC said:
Oh that description was perfect for my kind of brain, now I understand what the heck everyone is talking about (sort of) so the tow and tail are the highlight and blacks? So why does the upswept whatever mean, I didn't see a boomerang shape at all when I looked at the first OP's graph so I was totally confused (still am) so anyway this at least gets me a little more understanding.

Cool, that's what I aim for, is to make it understandable.

With film, the traditional layout is that the clear part of the film starts at the lower left. The "toe" (like on your foot) of the curve is where the film goes from clear to some moderate amount of density. Then there is a mid-range zone (a lot of people like to call this the "straight-line part," even if it isn't). Eventually, the line will stop climbing, and roll off in a "shoulder". Sometimes you don't see a shoulder, because it is so far off that it doesn't make it onto the graph - in these cases, the printing time would be so exorbitantly long that no one wants to go there. So there's no real need to graph it

Regarding the "boomerang shape," everybody gets their own descriptive words for things. I think he means the point where, halfway up, the line takes an upward bend; it's very slight. (I wouldn't personally say boomerang, 'cuz I'd get tired of explaining what I mean).

When they say the curve is "upswept," they mean it keeps getting steeper and steeper, at least in the "useable" part that is graphed. To me, in a "typical scene," (whatever that is), an upswept curve means that the highlight areas may be getting out of control. But if your subject doesn't have real highlights, this sort of film curve might build some in for you; closeups of fern leaves under soft light might be an example?

Hope this helps.

StoneNYC · Mar 19, 2013

Mr Bill said:
Cool, that's what I aim for, is to make it understandable.

With film, the traditional layout is that the clear part of the film starts at the lower left. The "toe" (like on your foot) of the curve is where the film goes from clear to some moderate amount of density. Then there is a mid-range zone (a lot of people like to call this the "straight-line part," even if it isn't). Eventually, the line will stop climbing, and roll off in a "shoulder". Sometimes you don't see a shoulder, because it is so far off that it doesn't make it onto the graph - in these cases, the printing time would be so exorbitantly long that no one wants to go there. So there's no real need to graph it

Regarding the "boomerang shape," everybody gets their own descriptive words for things. I think he means the point where, halfway up, the line takes an upward bend; it's very slight. (I wouldn't personally say boomerang, 'cuz I'd get tired of explaining what I mean).

When they say the curve is "upswept," they mean it keeps getting steeper and steeper, at least in the "useable" part that is graphed. To me, in a "typical scene," (whatever that is), an upswept curve means that the highlight areas may be getting out of control. But if your subject doesn't have real highlights, this sort of film curve might build some in for you; closeups of fern leaves under soft light might be an example?

Hope this helps.

It does a lot, I've been here for a year and no one has explained these graphs to me at all, now I get it (at least a lot more) thanks!

~Stone

Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk

albada · Mar 19, 2013

StoneNYC said:
It does a lot, I've been here for a year and no one has explained these graphs to me at all, now I get it (at least a lot more) thanks!

Once you know what to look for in a curve, it tells you a lot. For example, you'll know...

If shadows will look dark and mushy (long toe) versus snappy (linear or downswept).
If highlights will lack gradation (downswept) or be snappy (linear or upswept).
How much overexposure you can get away with (linear on right end).
Likewise with underexposure (short toe).

You can use curves to your advantage. For example, Bill Burk mentioned that an upswept curve can improve gradation in faces. A downswept curve will let you cram a large luminance-range onto the print by compressing highlights (example: snow/sand/clouds, where you also have something dark or shadows). Downswept also will give you strong shadow-gradation which can help in low-key shots. An S-shaped curve will have snappy midtones at the expense of reduced gradation in both shadows and highlights, which might be just what's needed to strengthen a midtone-heavy scene.

Developers and agitation change the shape of curves, so you can alter curves to suit your needs. I haven't seen curves produced by Diafine, but I'd guess they're downswept.
For general usage, a straight-line curve is best because it gives equal gradation in shadows, midtones and highlights.
Anyway, it's a good idea to be familiar with the curve for your film+dev combo so you'll know what you're going to get.

Mark Overton

StoneNYC · Mar 19, 2013

albada said:
Once you know what to look for in a curve, it tells you a lot. For example, you'll know...

If shadows will look dark and mushy (long toe) versus snappy (linear or downswept).
If highlights will lack gradation (downswept) or be snappy (linear or upswept).
How much overexposure you can get away with (linear on right end).
Likewise with underexposure (short toe).

You can use curves to your advantage. For example, Bill Burk mentioned that an upswept curve can improve gradation in faces. A downswept curve will let you cram a large luminance-range onto the print by compressing highlights (example: snow/sand/clouds, where you also have something dark or shadows). Downswept also will give you strong shadow-gradation which can help in low-key shots. An S-shaped curve will have snappy midtones at the expense of reduced gradation in both shadows and highlights, which might be just what's needed to strengthen a midtone-heavy scene.

Developers and agitation change the shape of curves, so you can alter curves to suit your needs. I haven't seen curves produced by Diafine, but I'd guess they're downswept.
For general usage, a straight-line curve is best because it gives equal gradation in shadows, midtones and highlights.
Anyway, it's a good idea to be familiar with the curve for your film+dev combo so you'll know what you're going to get.

Mark Overton

Hmm I've been just testing agitation styles and developers and seeing what I get, though fun it can be costly, this makes sense, I'll certainly re-read this when I'm at a computer and try and log it all to commit it to understanding and give reading curves a try.

Thanks again.

~Stone

Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk

T-Max 400 has boomerang curve

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