Pyro and T-Grain Films - Deux

Discussion in 'B&W: Film, Paper, Chemistry' started by Kirk Keyes, Nov 22, 2005.

  1. Kirk Keyes

    Kirk Keyes Member

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    Too bad the first thread died the death that most of us were expecting, but there were still a few points that I was interested in.

    Here's the premise that Sandy started the first thread with: (I added slashes which I hope clearifies the data a bit...)

    I guess my problem with the evidence as presented above is that while the data shows that the difference between the Vis and Blue values at Step 11 are very close to the same amount (and as Sandy points out the ratio is also close, percentage wise), the values of the Vis or Blue for the two films are quite different - for the first set of films - the FP4+ Vis is 0.92 and the TMax Vis is 0.67. A similar condition exists with the other pair of films - Tri-X Vis is 0.68 and the TMax Vis is 0.94.

    This looks to me that the two films have been developed to a different CI or gamma. I would suggest that these comparisions are not well matched. I suspect that if we matched a set of films where the visual density curves were nearly identical it would show that the T-grain films do not have the same level of stain that the non-T grain films have.

    My observation with PMK is that when this is done with FP4+ and TMX, the FP4+ has signifcantly more stain. I have not used TMY so I can't make any comments on it in PMK compared with Tri-X.

    Any thoughts?

    Kirk -
     
  2. Jorge

    Jorge Inactive

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    I disagree with your assesment. If you see the steps 1 and 21 you will see they are very close in values. Without seeing the middle values it is difficult to asses the liniearity of the films, but it seems to me that FP4+ has little "hump" in the middles values. If this is the case then I would think that for those subjects where the separation of the middle and dark values is important, then FP4+ would be a better choice than TMX 100.

    If we discount reading errors, I suspect that the reson for the differences in value 11 is that TMX 100 curve has a more linear behavior than FP4`+ which should have a more traditional S curve shouldering faster than TMX but at the same time moving out of the toe area faster than TMX as well.
     
  3. df cardwell

    df cardwell Subscriber

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    The choice of TMY and FP4 was excellent, at least for me: in my use, they share long straight lines, and Sandy's test bears this out.

    It is difficult to characterize film's response without mention of the associated developer. In my world, with Xtol and Rodinal, FP4 and TMY have well matched curves, and this data is VERY relevent.

    .
     
  4. sanking

    sanking Member

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    Kirk,

    You are absolutely right in that the films were developed to different average contrast. However, bear in mind that the only thing I wanted to demonstrate with the data is that for any given measurment of Visual Density T-grain films show about the same percentage of stain density increase when measured in Blue mode. This happens at both Step 1 and 11 so there is every reason to believe it would happen at any other step. In other words, whichever step you choose to measure the perentage of stain increase measured from Visual to Blue will be approximately equal for the traditional films as compared to the T-Grain films.

    Because of the very different nature of the curves of these films it is not possible to match visible densities all the way from Step 1 to 21. The basic curve shape of the different films, long toe, short straigh line section, and long shoulder for the traditional emulsion films, and shoe toe, long straight line and short shoulder of the T-grain films, simply won't permit a match, regardless of what portion of the curve you choose. There are obviously important implications that one must draw from this conclusion for the different way these films reproduce tonal densities on the print, but that is an issue not related to staining potential.

    Have you actually measured and compared the stain of FP4+ and TMAX-100 films developed in PMK in Visual and Blue modes, or is your comment based on a visual observation? I have tested PMK with T-grain films enough to know that they develop a significant stain, but don't have sample tests on hand to compare the actual percent increase with that of traditional films.

    Sandy
     
    Last edited by a moderator: Nov 22, 2005
  5. avandesande

    avandesande Member

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    tanning is a chemical reaction between the oxidation products of the development process and the gelatine. In T-grain films only major difference is the shape of the crystals, the chemisty is the same. There is no reason why t-grain films would tan any differently regular films.
     
  6. TimVermont

    TimVermont Subscriber

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  7. sanking

    sanking Member

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    One difference is that some films have thick emulsion that will develop a lot of what is called B+F or general stain. B+F stain is different from proportional stain in that it is is found in equal amounts in all areas of the negative, including the border areas. It is highly undesirable, at least in my opinion, because it offers no enhancement to image quality and increases exposure times.

    The post-development treatment in the used developer, which some authorities championed at one time, tends to produce a high percentage of B+F stain.

    T-grain films tend to produce very low B+F stain, which is perhaps one of the reasons many people came to believe that these films did not benefit very much from develoment in staining developers.

    Sandy
     
    Last edited by a moderator: Nov 22, 2005
  8. avandesande

    avandesande Member

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    I coined the term "general stain" on the M&P site years ago. I am embarrassed every time I hear it. Maybe somebody can come up with a better term.

     
  9. Ole

    Ole Moderator Staff Member Moderator

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    I changed the title of this thread.

    I apologise, but I just couldn't stand the spelling mistakes in what I sincerely hope will be an interesting and informative thread!

    BTW, I have found APX100 to stain rather more than most other films - can anyone corroborate that observation? Can anyone explain it?
     
  10. avandesande

    avandesande Member

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    My guess that 'fog stain' is more prevelant in films with a gelatine that is a lower molecular weight or has less cross-links. Photoengineer probably has a better explanation than me.
    Since tabular grains orientation (perpindicular to the lens) is very important, I would bet that a very 'hard' gelatin was used to keep the grains flat. The oxidation stuff from pyro doesn't migrate through the gelatine very easily and it reacts with the gelatine right next to the silver particle.
    I am no photo engineer and this is a guess.
     
  11. jim appleyard

    jim appleyard Member

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    What! Speling misstakes hear? Say it ain't sew!

    I get a nice stain with APX 100. Moor than other films? Don't no yett, butt it could bee.
     
  12. df cardwell

    df cardwell Subscriber

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    One of the vital things lost since the deaths of Adams and Minor White has been their sense of perspective. Both teachers placed personal expression ahead of technical perfection, then introduced techniques appropriate to serving the visionary needs of photographers. In his Introduction to The Camera, Adams discussed visualisation, calling it "the foundation of this and all the projected books of (his) series". Visualisation, to Adams, "is to see (an image) clearly in the mind prior to exposure, a continuous projection from composing the image through the final print."

    He called it "an attitude toward photography rather than a dogma." He warned consistently that it was better to make a fuzzy picture of a clear idea " than a brilliant image of a fuzzy concept."

    In the past 20 years, there has been an astonishing general achievement in making dazzling images that are empty of all emotion, and of no value at all. There is no conversation today among writers, readers or practitioners that acknowledge the foundation of all of Adams' teaching, visualisation. Instead, there is obsession over technical virtuosity driven by a literalist dogma of what constitutes a 'good picture' or proper technique.

    Neither Adams, White, nor any truly good teacher ever allowed ideology to limit their students' picture making, BUT taught appropriate methods to support personal vision with the necessary technique. Today, however, we witness jihad on those who would defy the narrow minded certainties of limited technical approaches, usually based on the magical properties of certain materials, equipment, or a superstituous approach to sensitometry.

    I have to commend Sandy King on his willingness to share his data, presented clearly and generously, and to let folks make of it what they will. He follows the intelligent and open hearted tradition of photography propounded by Adams, unlike those who would limit the practise of expressive photography to rote formula and meaningless technical orthodoxy and correctness.

    .
     
  13. jd callow

    jd callow Moderator Staff Member Moderator

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    Don,
    An excellent post, as always.
     
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  15. sanking

    sanking Member

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    What? Duex is not Norwegian?

    Sandy

     
  16. Photo Engineer

    Photo Engineer Subscriber

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    Just FYI, older articles in photo journals report that gelatins with different 'hardness' or Bloom Index, were used for controlling contrast. I see no indication of this. What I do find is that lower BI gels actually harden up more than gels of higher BI, but coat differently due to viscosity, so things are not so simple.

    Early T-Grain films could not be made in 120 and 220 size. The reason was that the tight turns in the 120 and 220 backs caused grain cracking and fog in the emulsion. The emulsion was too stiff and the path was too curved and the grains were 'broken' by mechanical stress. Addition of softer gels, polymers and humectants helped cure the problem IIRC.

    PE
     
  17. TimVermont

    TimVermont Subscriber

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    So Let's Get Our Good Teachers Talking About Necessary Technique

    My reference to Adams was simply to set a baseline of time and method. A discussion of visualization/ pre-visualization deserves a thread of it's own.

    If there are new methods that reduce the learning curve for paper and films -"necessary technique"- I'd like to know about them. Executing my personal vision will have to change once my stocks of no longer available film and paper run out. I suspect many reading APUG are in the same condition.
     
  18. Kirk Keyes

    Kirk Keyes Member

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    Perhaps this is one reason that more moderm emulsion designs could lead to relatively less staining?

    Kirk - www.keyesphoto.com
     
  19. Kirk Keyes

    Kirk Keyes Member

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    Thanks, Ole. I saw I had the Pryo in there! I thought, "Mon Dieu", did I spell duex wrong - for just a second! Or did I?
     
  20. phfitz

    phfitz Member

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    Hi there,

    I must have missed something on the first thread. I don't think the point was if Tmax stains or not but rather does it actually make a difference with Tmx100 sheet film.

    So directly, is there a legitimate, compelling reason to change over from D76/ Xytol/ TmaxRS to a staining pyro developer for Tmax Tmx100 sheet film?

    Will the stain mask reduce the apparent grain?
    Will the stain mask work with the built-in U.V. blockers?
    Will it raise the apparent sharpness with an edge effect?
    Will it raise the film speed?
    Will it soften the toe or introduce a shoulder?

    Is it actually worth changing over if one does not use a pyro developer?
     
  21. Kirk Keyes

    Kirk Keyes Member

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    I'm fine with the Step 21 densities, they are suitably close for me to make a comparision here.

    I do find that perhaps Step 1 was perhaps not the best choice to use as the densities for it are all above 2.00. I thought we were discussing the use of staining developers with VC papers as that was what Mr. Simmons was using in his examples. If so, then I find the behavior of most any developers at a neg density of 2.00 to be pretty moot. Afterall, we're we chiding Simmons about not having better matched his development in his past tests. And I would expect part of this to be matching the film development to the Log Exposure Range of the printing paper. Do the films in these examples match the LER or "normal" silver paper?

    Perhaps I'm not sure which printing process we are talking about - if it is regular or VC paper, then I would guess that CI of the developed film should be around 0.6 or so and have a LER of a bit over 1.00. Do the films in these example match some particular paper? If Azo, then what, LER around 1.6? That's probably a better match to Sandy's data.

    I understand that the films will different linearities, but I suggest that the density ranges of the Vis data be better matched and have similar CIs. We don't need to match every single Step for each film to make this comparison.

    Just want to make sure we are comparing apples and apples here.

    Kirk
     
  22. Kirk Keyes

    Kirk Keyes Member

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    Well certainly - that's where I'm basing my observations. Vis, Blue, Green, and Red. I've even made spectrometric measurements of the stains from UV to near IR -
     
  23. Kirk Keyes

    Kirk Keyes Member

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    Yes, that is an excellent question - I think everyone will come up with different personal answers for it.

    Also, Sandy made mention of resolution benefits as well. Perhaps we can address that too, as even though you may decide the stain is not enough reason, maybe if there is a resolution benefit, then it may be. I can't address that as I have not done sufficient testing to say.
     
  24. Photo Engineer

    Photo Engineer Subscriber

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    Kirk, yes, if you replace a portion of gelatin with a polymer, then that polymer is not as likely to stain.

    However, if there is an advantage in one formula, it is often adopted across the board to make all of the formulas more uniform and consolidate problem areas to similar conditions. So, in the end, I'm afraid that the polymers would end up in K-grain films as well. And that is what happened AFAIK.

    I apologize for not extending that last answer to include this information. I should have.

    PE
     
  25. sanking

    sanking Member

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    Kirk,

    The specific CI of the negatives is irrelevant to this issue. The question is simply this. If you select any specific density, say .90, on the step scale for both the traditional and T-grain film, what is the relationship of silver density (Visual mode) to silver density plus stain (Blue mode) between the two?

    Obviously the negative set I selected has a fairly high CI. However, a lower CI would not have changed the relationships at any specific measured Visual density. If Step 11 has a measured Visual density of .90 and a measured Blue mode density of 1.30, that same percentage increase would continue to exist if the negative were developed to a lower CI and the Step 11 denstiy of .90 were shifted to Step 1. I am not speculating. I observe the same relationship in other negatives in the sets from which these were taken.

    If you have step wedge tests of TMAX-100 and FP4+ developed in PMK, post them here and I will find an equivalent pair of negatives of approximately the same CI developed in Pyrocat-HD to compare data for the two developers.

    Sandy
     
    Last edited by a moderator: Nov 23, 2005
  26. sanking

    sanking Member

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    So far as I understand the only explanation that has ever been offered as to why TMAX films do not benefit from staining developers is the suggestion that they do not stain well, or that they don't stain well as other films.

    But I will take a shot at your questions? Bear in mind, there is some supposition here.

    Will the stain mask reduce the apparent grain?
    I believe it will. However, T-grain films, espcially TMAX-100, already have very reduced apparent grain compared to traditional films of equivalent ISO, so you might have to make a fairly large print before there would be any difference.

    Will the stain mask work with the built-in U.V. blockers?
    Yes, the stain has its own density apart from that of the UV coating. Of course, the UV coating on TMAX-100 makes it virtually useless for UV processes, but that is another story.

    Will it raise the apparent sharpness with an edge effect?
    I believe so. However, the T-grain films are already significantly sharper than traditional films because of better resolution, so you may have to make very large prints to see a differnce. Bear in mind that tests for sharpness should always be based on multiple samples at equivalent lens aperture because the tolerance of ground glass position introduces errors that are usually greater than the real difference between any developers.

    Will it raise the film speed?
    That depends on the formula. However, real differences in EI that can be attributed to the developer are very small, in fact much too small to be measured except with sensitometry, and then only with systems that provide 100% consistency in exposure, i.e. sensitometers or light iintegration systems. The accumulated errors of camera systems and development (aperture setting, shutter inaccuracies, solution and temperature control in the darkroom, consistenty of exposure when printing) introduce errors that are potentially well beyond the small differences that may exist in the EI potential of two developers.

    Will it soften the toe or introduce a shoulder?
    This depends on 1) choice of developer, and 2) printing process. Developers that produce a greeen stain cause more shoulder compression than those that produce a brown stain. Compression is good for some subjects, undesirable for others. If you understand and apply this concept you will have a far greater understanding of staining developers than many persons who consider themselves expert in their use.

    Sandy
     
    Last edited by a moderator: Nov 23, 2005