T-Max 400 has boomerang curve

StoneNYC · Mar 19, 2013

Michael R 1974 said:
Just don't get too carried away with it, Stone. Often people plot curves and think they know what they are going to get but drawing meaningful conclusions from the data can actually be tricky. There are different ways of testing, and many variables, including differences between testing conditions and shooting conditions.

You might want to get yourself a copy of Ansel Adams's The Negative. There is an easy to understand primer on densitometry and characteristic curves in the book.

Incidentally, to anyone who owns a copy of Haist, the end of the first book has a pretty good chapter on sensitometry/densitometry, curves etc. Just mentioning it because while Haist is a common reference for photochemistry, there's other excellent stuff in there too.

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

DREW WILEY · Mar 19, 2013

The most important thing is to plot different film/chem curves all in the same manner, so that comparisons will be meaningful. It also helps to show multiple curves with different development times.
I also try to plot the same kind of log spacing characteristic of published mfg curves (on the tech sheets), so that it is intuitive to read these as well. It tells you a great deal at a glance if you know
what to look for.

albada · Mar 28, 2013

This morning, Michael R posted his curves of TMY-2 (same batch as mine) here:
(there was a url link here which no longer exists)

He got the same boomerang shape, with the inflection in about the same place. So that shape is really there, and was not my mistake. But as another poster pointed out, I hope the slope-change is small enough that most people won't be bothered by it.

Mark Overton

Photo Engineer · Mar 28, 2013

Try bringing this to the attention of the guys at EK.

PE

EASmithV · Mar 28, 2013

noacronym said:
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.

I agree. I hate the way T-max looks in all but perfect or controlled lighting.

StoneNYC · Mar 28, 2013

EASmithV said:
I agree. I hate the way T-max looks in all but perfect or controlled lighting.

I've found if you rate Tmax400 at EI320 and develop in Rodinal 1:50 at 1/2 stop longer standard dev time (about 1 to 1.5 minutes longer) you can get more pleasing results to what you and I like

Try it. Oh and you need to only gently agitate 1 inversion per minute instead of a bunch and VERY gently and that seems to help a LOT

~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

noacronym · Mar 28, 2013

Having skimmed through the posts on this thread seems to take the reader into never-never land. Too many variables, and lack of credibility (to me). Somehow I would think the real poop on the matter is best left to the scientists at Eastman Kodak. If that's not good enough, nothing else would be of any consequence (to me alone, maybe).

c6h6o3 · Mar 28, 2013

Curves shmurves. 400TMax has the longest, straightest response curve of any film I've ever used. Take a look at this photograph, shot on 8x10 400TMax sheet film. There are approximately 12 zones between the shadows in the vaults and the highlights in the rosette. The proof of the pudding is in the tasting.

Having said that, I should also point out that I've heard that there's a difference between the TMax roll film and the sheet film; namely, that there's a dye in the roll film that blocks UV. I don't know if that is true or not. Maybe Ron knows. If true, it might account for your results differing so drastically from my experience.

noacronym · Mar 29, 2013

c6h6o3 said:
Curves shmurves. 400TMax has the longest, straightest response curve of any film I've ever used. Take a look at this photograph, shot on 8x10 400TMax sheet film. There are approximately 12 zones between the shadows in the vaults and the highlights in the rosette. The proof of the pudding is in the tasting.

Having said that, I should also point out that I've heard that there's a difference between the TMax roll film and the sheet film; namely, that there's a dye in the roll film that blocks UV. I don't know if that is true or not. Maybe Ron knows. If true, it might account for your results differing so drastically from my experience.

Your link seems to require the reader have a facebook account. As for me; no thank you.Wish you'd have just posted an attachment here.

albada · Mar 29, 2013

noacronym said:
Your link seems to require the reader have a facebook account. As for me; no thank you.Wish you'd have just posted an attachment here.

I downloaded Jim's pic. With his permission, I'll post it to this thread.
It's a stunning shot of the interior of a cathedral consisting mostly of shadows and midtones, with solid white highlights in the stained glass.

Mark Overton

DREW WILEY · Mar 29, 2013

It's still a curve. Such things differ from one film to the next, and relative to the development regimen.
I've done analogous shots with 8X10 TMY looking out from very dark tunnels, with detail reproduced over a very long range indeed (and I'm not referring to minus or compensating development, where the
midtone tonality gets compressed). But one still has to understand at what threshold value the shadows will indeed be decently differentiated, and at what point the highlights will simply blow out relative to the given print media (which can be employed creatively, of course). But if one does plot such things on a densitometer, TMY does have a lot of range for the sake of practical photography, but not quite as much as a few other films I've tested, which aren't commercially available anymore. The
verstility and quality of TMY makes it my favorite "go to" 8x10 film, yet also my favorite 35mm snapshot product.

Photo Engineer · Mar 29, 2013

Virtually every film has a UV absorber. It is either an incorporated dye (yellow) or in an overcoat.

As for the curve, my boss used to say "we don't sell curves, show me a picture". So, all of the comments above are useless if that film makes a good picture and the release curve is within specs.

That is why I suggested that you call EK.

PE

albada · Mar 29, 2013

Photo Engineer said:
That is why I suggested that you call EK. PE

I just sent EK a description of the issue. We'll see what they say...

Mark Overton

DREW WILEY · Mar 29, 2013

Curves mean a helluva lot once you start doing something outside the routine - color separations for
example, where you need to know not only where the linearity begins and ends, but how consistent it
is between radically different color filters, along with potentially differing exposures and their kind of
recip failure effect. I how know idea how they figured it out, but if you understand how the film works,
both speeds of TMax are remarkably consistent in this respect too. In the more ordinary world, just head over to our coastal redwoods - a film which might give wonderful results in a morning fog will be
just about useless once the sun breaks out and you end up with maybe fourteen stops of range, a task
just about impossible for any film without a steep toe unless you turn the whole thing into mushy
compensating dev. Even with TMY under such circumstances, I sometimes have to resort to supplemental unsharp masking, even with the finest VC papers. Curves mean a helluva lot in my world.

DREW WILEY · Mar 29, 2013

Sorry to sound like a wiseguy, Ron ... but I'm really trying to relate the wonderful versatility of TMax if
one understands the curve characteristics. Right now (besides general shooting) I'm applying TMax to
color neg masking. This is radically different than good ole Ciba masking ala battleaxe and spike ball
sheer force, and way more fussy than garden-variety masking for black and white printing. It's like power steering - very delicate, and ideally requiring a straight line way to the bottom of the relevant
curve even under extremely low-contrast development. This characteristic becomes critical with multiple
generation masking work - and by golly, TMax can do the job a helluva lot better than the oft-lamented
long-lost late Pan Masking film ever could. And if it can do that, as well as provide very long scale
relatively high-contrast predictable separation negatives, for example, that's a remarkably versatile
product!

noacronym · Mar 29, 2013

Since none of us here knows one another, there is not much basis for definitive laboratory testing. Now if the original poster had also posted the technical receipt from the company where he sent his densitometer to be calibrated then I'd take notice. Calibration of instruments is a daily routine for companies that use these kinds of devices. If a record studio using tape recorders is in the business of quality records and tapes, it would be the engineers job to check tape head alignment, azimuth, and do tests on frequency response, probably before each studio session. A densitometer needs the same attention. When you send your oscilloscope off to Tektronics to be calibrated, you undoubtedly receive a printed report back with your scope. Densitometers can go out of calibration in one day, if you don't keep on top of them every minute. Anything less is just sloppy procedure, and the results are worse than worthless.

Bill Burk · Mar 29, 2013

noacronym said:
Since none of us here knows one another, there is not much basis for definitive laboratory testing. Now if the original poster had also posted the technical receipt from the company where he sent his densitometer to be calibrated then I'd take notice. Calibration of instruments is a daily routine for companies that use these kinds of devices. If a record studio using tape recorders is in the business of quality records and tapes, it would be the engineers job to check tape head alignment, azimuth, and do tests on frequency response, probably before each studio session. A densitometer needs the same attention. When you send your oscilloscope off to Tektronics to be calibrated, you undoubtedly receive a printed report back with your scope. Densitometers can go out of calibration in one day, if you don't keep on top of them every minute. Anything less is just sloppy procedure, and the results are worse than worthless.

I wouldn't go so far as that. I called up a radio station a while back because my oscilloscope was showing a 45-degree line where the stereo scatter fuzzy oval should be. They thought I was a lunatic until I double checked by listening in my car. No it wasn't my equipment. And my scope is nowhere near calibrated. All their lab equipment was switched on the digital signal so they didn't notice the board on the analog side was switched to mono.

Meanwhile to add a possibly useful question to the thread. Is this the kind of step wedge layout used for testing?

(there was a url link here which no longer exists)

If so, can you test with an offset, or 90-degree angles to your usual. Maybe you are seeing an effect where the outside edge of the film receives greater development than the center.

p.s. I work for Kodak, but not in film - here I am a hobbyist. The opinions and positions I take are my own and not necessarily those of EKC.

DREW WILEY · Mar 29, 2013

A lot does have to do with the nature of your step tablet or wedge, esp if they are old and discolored.

noacronym · Mar 29, 2013

Bill Burk said:
I wouldn't go so far as that. I called up a radio station a while back because my oscilloscope was showing a 45-degree line where the stereo scatter fuzzy oval should be. They thought I was a lunatic until I double checked by listening in my car. No it wasn't my equipment. And my scope is nowhere near calibrated. All their lab equipment was switched on the digital signal so they didn't notice the board on the analog side was switched to mono.

Meanwhile to add a possibly useful question to the thread. Is this the kind of step wedge layout used for testing?

(there was a url link here which no longer exists)

If so, can you test with an offset, or 90-degree angles to your usual. Maybe you are seeing an effect where the outside edge of the film receives greater development than the center.

p.s. I work for Kodak, but not in film - here I am a hobbyist. The opinions and positions I take are my own and not necessarily those of EKC.

Pardon me for that, Mr Burk. I'm mostly a hobbiest, but also something of a calibration nut. If you put an instrument into my hands, by nature the first thing I'll invariably do is open it up and calibrate it. Frequency generators, scopes, tape recorders, camera, light meters... If it is something that can be calibrated, I'm bound to calibrate it. Can't help myself.

DREW WILEY · Mar 29, 2013

Modern densitometers often have a "null" mode relative to the light source, so if a little dust gets on
the receptor, it is ignored. Actual calibration requires an expensive reference standard - a very expensive kind of step wedge - and not just an ordinary one on film. But you can use your ordinary step wedge to check for any drift. I once worked quite a bit with spectrophotometers, and these had to be routinely recalibrated to a fade-proof standard, typically a white ceramic tile. I've been working with
the same pair of densitometers for several decades, and they are still within .01 measured density -
below the advertised plus/minus accuracy factor!

Bill Burk · Mar 29, 2013

noacronym said:
Pardon me for that, Mr Burk. I'm mostly a hobbiest, but also something of a calibration nut. If you put an instrument into my hands, by nature the first thing I'll invariably do is open it up and calibrate it. Frequency generators, scopes, tape recorders, camera, light meters... If it is something that can be calibrated, I'm bound to calibrate it. Can't help myself.

Ah, and pardon me too noacronym. I know that calibration is good and helps to establish credibility.

Photo Engineer · Mar 29, 2013

I am not criticizing Tmax nor am I extolling its virtues. I am merely pointing out what was brought forward in this thread. Several batches of the same film seem to have different curves. These curves may be indicative of a problem or they may be at the extremes of the nor for released product. But, there have been samples run through the same process taken from different batches of film, and they differ. This is not a problem with a densitometer nor is it a problem with a process as these two results seem to be possible from the same exposure and process.

So let us avoid the side non-issue of calibration and etc. and look at the results which are odd to say the least. And therefore, contacting EK may help, as Bill Burk has pointed out in his story!

And remember, some of us do know one another either in extensive exchanges of private mail, or in person!

PE

noacronym · Mar 29, 2013

Photo Engineer said:
I am not criticizing Tmax nor am I extolling its virtues. I am merely pointing out what was brought forward in this thread. Several batches of the same film seem to have different curves. These curves may be indicative of a problem or they may be at the extremes of the nor for released product. But, there have been samples run through the same process taken from different batches of film, and they differ. This is not a problem with a densitometer nor is it a problem with a process as these two results seem to be possible from the same exposure and process.

So let us avoid the side non-issue of calibration and etc. and look at the results which are odd to say the least. And therefore, contacting EK may help, as Bill Burk has pointed out in his story!

And remember, some of us do know one another either in extensive exchanges of private mail, or in person!

PE

Well I don't know any of you guys. And if I met a few of you I can think of, I'd probably be asking for your autograph.

Photo Engineer · Apr 16, 2013

To me it looks like a blending problem.

PE

Shawn Dougherty · Apr 16, 2013

I scanned back through this thread because I thought someone mentioned what you might expect from such a curve in a real world printing situation but I couldn't find it. Could someone lay that out here, for my sake? I understand the basics of toe, shoulder, straight line areas but this shape is a bit confusing to me. Thanks in advance.

T-Max 400 has boomerang curve

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