Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,915   Posts: 1,556,357   Online: 1067
      
Page 3 of 10 FirstFirst 123456789 ... LastLast
Results 21 to 30 of 97
  1. #21
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,187
    Images
    65
    Microdensitometry in this instance has nothing to do with granularity whatsoever.

    As for measuring a 1mm square, I am referring to the density across exposures as small as a 1 MICRON step. In fact, I refer to a step scale consisting of 21 densities each 1 MICRON across, and which is measured for density by a precision instrument to guage the micro contrast of an image. It is, of course, a measure of edge effects.

    Reading the integrated density of the exposure gives total percieved density and reading density as a function of distance across the exposure measures edge effects.

    For example, features on a human face in a scene in 35mm may consist of 1 or 10 micron details. The details on the rock in the picture under discussion may consist of 100 down to 1 micron width details depending on original negative size. The effects of development on structures this small vary with agitation and with developer type.

    Edge effects can affect both positive changes and negative changes in micro contrast that go unseen in routine densitometric analysis of spots larger than 100 microns such as you describe.

    As I said above, this type of analysis goes largely (well almost completely) unmentioned and unrecognized in these sorts of discussions but is performed routinely by engineers at companies such as Agfa, Fuji, Ilford, and Kodak.

    This effect is discussed by M. Kriss in a fine article on image structure published by the SPSE. It is also referred to by Mees and James.

    If there is such a thing as a microdensitometer (and there is, I assure you) it is of vital importance to one who designs developers. And the reason it is, is that these variations do show up in a print, but it depends on magnification, as I stated here and above. I ask you to please sit down and consider the implications of what I am explaining.

    I am not criticizing anything or anyone. I am trying to heighten awareness to an almost completely overlooked aspect of the design and use of developers. I am also trying to explain how one can actually quantize the effects of stand or other types of development and how thereby one can learn to optimize its effects. Understanding a tool or method is the key to using it better.

    PE

  2. #22

    Join Date
    Mar 2003
    Location
    Greenville, SC
    Shooter
    Large Format
    Posts
    4,813
    Images
    5
    Quote Originally Posted by Photo Engineer

    As I said above, this type of analysis goes largely (well almost completely) unmentioned and unrecognized in these sorts of discussions but is performed routinely by engineers at companies such as Agfa, Fuji, Ilford, and Kodak.

    This effect is discussed by M. Kriss in a fine article on image structure published by the SPSE. It is also referred to by Mees and James.

    If there is such a thing as a microdensitometer (and there is, I assure you) it is of vital importance to one who designs developers. And the reason it is, is that these variations do show up in a print, but it depends on magnification, as I stated here and above. I ask you to please sit down and consider the implications of what I am explaining.

    I am not criticizing anything or anyone. I am trying to heighten awareness to an almost completely overlooked aspect of the design and use of developers. I am also trying to explain how one can actually quantize the effects of stand or other types of development and how thereby one can learn to optimize its effects. Understanding a tool or method is the key to using it better.

    PE
    There are several reasons why discussions such as this one don't mention the knife-edge test and measurements of micro-densities across adjacency lines. The most obvious one is that to carry out this type of testing requires very expensive instrumentation to which few if any of us have access. Richard Henry did some testing of this type, described on pp. 30-33 in Controls in Black and White Photography, but reproducing his testing system would be quite complicated, in fact probably beyond the level of expertise of most people on this list.

    Secondly, and most important, most of us are more interested in apparent sharpness, and for this the human eye is the only thing that really matters. When film is developed in such a way that there are very enhanced edge effects due to micro-contrast it happens that the visual result of the effects is quite visible to the eye as greatly increased apparent sharpness, both in the negative and on the print. It is not a subtle thing, but a look that hits you in the face.

    Sandy
    Last edited by sanking; 08-11-2005 at 10:27 PM. Click to view previous post history.

  3. #23
    gainer's Avatar
    Join Date
    Sep 2002
    Posts
    3,726
    Images
    2
    Nevertheless, the small variations of density that I saw were plainly visible and of such a nature as to make stand development unattractive for critical use. Furthermore, as I said, there is seldom an effort made to separate the effects of developer constitution and method of agitation. It is possible that a combination of developer characteristics combined with stand development will overcome those defects. It is also possible that the same developer with continuous agitation might show all the advantages of stand development. My criticism of microdensitometry is that it deals with image characteristics that the eye either cannot see or that are obvious to the eye. There is no need to measure what the eye cannot see in a negative or print, and there is no need to measure what is obvious to the eye for most of us. I can see bromide drag with my bare eyes, and I can see the artifacts we call edge effects, sometimes even when there are none. The eye will supply an edge effect along the edge of a dark building against a bright sky.

    Whatever instruments may be used to analyze that which causes what we see, the analysis will be flawed if it does not follow a proper experimental design.
    Gadget Gainer

  4. #24

    Join Date
    Mar 2003
    Location
    Greenville, SC
    Shooter
    Large Format
    Posts
    4,813
    Images
    5
    Quote Originally Posted by gainer
    Nevertheless, the small variations of density that I saw were plainly visible and of such a nature as to make stand development unattractive for critical use. Furthermore, as I said, there is seldom an effort made to separate the effects of developer constitution and method of agitation. It is possible that a combination of developer characteristics combined with stand development will overcome those defects. It is also possible that the same developer with continuous agitation might show all the advantages of stand development. My criticism of microdensitometry is that it deals with image characteristics that the eye either cannot see or that are obvious to the eye. There is no need to measure what the eye cannot see in a negative or print, and there is no need to measure what is obvious to the eye for most of us. I can see bromide drag with my bare eyes, and I can see the artifacts we call edge effects, sometimes even when there are none. The eye will supply an edge effect along the edge of a dark building against a bright sky.

    Whatever instruments may be used to analyze that which causes what we see, the analysis will be flawed if it does not follow a proper experimental design.
    I agree with you that that micro density measurements are of no practical consequence to photography because the artifacts of adjacency effects are plainly visible to the naked eye, sometimes as a pleasant increase in apparent sharpness, at other times as unpleasant artifacts.

    I don't agree with you that there is no effort made "to separate the effects of developer constitution and method of agitation." In fact, that is exactly what we do when we use very dilute developer solutions with reduced agitation. Let me assure you that the kind of extreme adjacency effects observed by Steve Sheman and others in working with very dilute solutions of Pyrocat-HD in the 1:1:200 range with extreme minimal or semi-stand agitation can not be replicated with very dilute solutions and continuous agitation using dilutions in that range. It is possible that an even weaker dilution could be used with rotary agitation that would produce the same level of adjacency effects but dilutions in the 1:1:500 to 1:1:1000 range would likely suffer overall exhaustion before adequate overall contrast could be reached.

    Regardless, the plain fact of the matter is that the more the film rests during development the greater will be the adjacency effects, and this is true of most non-solvent developers when used at an appropriate dilution. I have personally never observed the development of extreme adjacency effects with any method of agitation other than semi-stand and stand, regardless of developer composition/dilution. If this can be achieve with continuous rotary agitation, show me. I have experimented with many solutions in an effort to do this and thus far been unable to do so.

    Sandy
    Last edited by sanking; 08-12-2005 at 06:26 AM. Click to view previous post history.

  5. #25
    df cardwell's Avatar
    Join Date
    Jul 2005
    Location
    Dearborn,Michigan & Cape Breton Island
    Shooter
    Multi Format
    Posts
    3,342
    Images
    8
    Quote Originally Posted by gainer
    ... there is seldom an effort made to separate the effects of developer constitution and method of agitation. It is possible that a combination of developer characteristics combined with stand development will overcome those defects. It is also possible that the same developer with continuous agitation might show all the advantages of stand development. ...

    Whatever instruments may be used to analyze that which causes what we see, the analysis will be flawed if it does not follow a proper experimental design.


    I don't mean to be argumentitive. I guess it comes naturally.

    With complete awareness of the need for proper method , I began an investigation into the effect of agitation of Rodinal, in various dilutions, on Tri X and Plus X.

    Like many young photographers ( long ago, I'm afraid ) I cast about for a magic combination of film and developer, and when I landed on Rodinal and Tri X I thought I had found the magic combination ! In retrospect, my progress at the time may have had something to do with a great deal practise, the need to please an editor, and the influence of patient and inspirational photographers. At the time, however, the ritualized processing of film did wonders for me.

    I began Jobo processing : I was shooting an equal amount of color negative and B&W. I had also become obsessed with the (now conventional ) evaluation of negatives based on low value densities. Overnight, my pictures were completely different, and it was not at all an improvement. I wrote it off as something done to me by The Great Yellow Father, and pressed on. In time, I did a comparison of manual agitation to constant agitation and found a visible, consistent, and quantifiable difference. Suffice it to say my method was adequate to the job.

    I compared dilutions, agitation, time, and temperature. I proved to my satisfaction that curve shape could be altered by agitation. More importantly, it was obvious that by viewing the development process as a system, the response of the film could be predicted and controlled.

    I don't know what to say next. It's easy for me to be intimidated by charts, graphs, and a scientific attitude.

    All I want is to make pictures look the way I want. And, if possible, to share what I've learned along the way, so (maybe) other folks who like pictures can get to their goals faster than did I.
    "One of the painful things about our time is that those who feel certainty are stupid,
    and those with any imagination and understanding are filled with doubt and indecision"

    -Bertrand Russell

  6. #26
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,187
    Images
    65
    I guess you guys just don't get it.

    I agree that a qualitative asessment of photographs is useful and has stood the test of time, but there is such a thing as a quantitative measurement that exists that is ignored. That is the root of my post.

    It is also true that the eyeball can be tricked easily. And, opinions differ. If you don't believe this, just read the posts in this thread about the utility of stand or semi-stand development, or the arguments over which developer is better. It is preference, not quantization. And don't get me wrong, I don't believe quantization should overrule art, it is merely another tool.

    As to having instruments available? Well, that is largely the decision of the people who want the instruments or who design them and who don't know or believe this type of scientific approach is useful. A scanner can serve as a very useful microdensitometer (of sorts) and I have several definitition charts (from commercial sources) that can serve to make the proper exposures. It can be done, it just is not done.

    I have seen posted several formulas for color films (C41 and E6) which are incorrect, and the errors in them will lead to inadequate or improper edge effects and color reproduction. I note that the pictures that purport to represent negatives and slides from these processes look quite good. But no quantitative asessment was made to compare them exactly to the reference process. "They just look good".

    So, if they look good to you, who is to argue. I am not presenting an argument. I am presenting an alternative to guesstimation and judement that might just improve our collective knowledge and the potential for better results photographically.

    I am trying to open up a new dimension to your very good qualitative thinking to the quantitative arena in which you can say "that is a beautiful picture", "this is my opinion as to why it looks so (instert buzz word here)" and now you can add if you wish "here is the measurement to prove that the (grain, sharpness, edge effects, micro contrast - or other buzz word) is improved or better than the other print".

    In other words, what about this developer or methodology makes things better, and by how much can be measured.

    Its a new tool. Use it or not.

    PE

  7. #27
    gainer's Avatar
    Join Date
    Sep 2002
    Posts
    3,726
    Images
    2
    Tools are fine. Measurement devices are good. In my case, it's just that I don't see how a microdensitometer is needed to show the virtues or vices of stand development. I couldn't afford a densitometer, so I made my own. It has a very small sensitive area, can be used to measure zones in the projected image as well as densities, has a quite accurate logarithmic response, and cost me less than $50. With it, I can quantify irregularities that sometimes result from stand development. Tell me again why I should have used a microdensitometer with a 1 micron window for my 35 mm film? If I blow that up 1000 times, it's only a millimeter! At reading distance, my eyes can resolve about 1/10 mm. And when I have examined a negative with this microdensitometer, what do I know about stand development that I did not know before? Does it tell me any more about the pictorial density range than a test print or a reading from an ordinary densitometer?

    If you have a microdensitometer and can use it to show us what we need to know, I'm sure we all would appreciate your doing so. For my part, whenever I can, I present results that could be verified by most if not all of our readers, here and when I write for Photo Techniques. I'm not saying that this is always necessary, but when it is not done, a rational experimental plan should be used.
    Gadget Gainer

  8. #28
    lee
    lee is offline
    lee's Avatar
    Join Date
    Nov 2002
    Location
    Fort Worth TX
    Shooter
    8x10 Format
    Posts
    2,913
    Images
    8
    I dont really need or want to measure microdensities. I just want sharp negs and if stand development gives me that then the rest can pound sand. This is not photography as I see it, this is testing. I just need to make images and if stand development helps me then so be it. Quantify or qualify all you testers want. Does it make your images better or do you even make images behond what you need for testing?

    lee\c
    Last edited by lee; 08-12-2005 at 12:07 PM. Click to view previous post history. Reason: spelling

  9. #29
    gainer's Avatar
    Join Date
    Sep 2002
    Posts
    3,726
    Images
    2
    Quote Originally Posted by sanking
    I agree with you that that micro density measurements are of no practical consequence to photography because the artifacts of adjacency effects are plainly visible to the naked eye, sometimes as a pleasant increase in apparent sharpness, at other times as unpleasant artifacts.


    Regardless, the plain fact of the matter is that the more the film rests during development the greater will be the adjacency effects, and this is true of most non-solvent developers when used at an appropriate dilution. I have personally never observed the development of extreme adjacency effects with any method of agitation other than semi-stand and stand, regardless of developer composition/dilution. If this can be achieve with continuous rotary agitation, show me. I have experimented with many solutions in an effort to do this and thus far been unable to do so.

    Sandy
    Adjacency effects were farthest from my mind when I made that statement. The most salient argument made for stand development always seemed to me to be its effect on the characteristic curve, its compensatory action. I have not found any significant change due to agitation, from none to 3 inversions every 30 seconds. True, I did not use the extreme dilutions. That was not part of the theory of compensatory action. None of the praisers of stand development had said much about dilution or other qualities of the developer. I considered that aspect to be a subject for a different investigation.

    If stand development did nothing for (or against) the H&D curve, it might still have effects on apparent sharpness, but in the process of finding what I did, I also found very definite unpleasant artifacts. Stand development in itself was not universally desirable. If those defects are cured by altering the developer, that is fine, but still the subject of a separate investigation.

    My original complaint in this thread was simply that Steve Sherman pointed to a photo on which he did not use stand development as a reason for using stand development. From all I could see, it was an excellent picture.
    Gadget Gainer

  10. #30
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,187
    Images
    65
    Quote Originally Posted by gainer
    I have tried it, though not perhaps in the way you would approve. I did some characteristic curves with and without agitation. Since the purpose was to find the effect of no agitation vs agitation, I used the same developers in both cases. I found that the developing times had to be 40% longer to get the same contrast index for each of two developers. In neither case was there any significant difference in shape of the curve.
    This is the phrase that kicked off my comments here. Mr Gainer was using a characteristic (macro) curve to compare agitation vs no agitation. My point was that a macro curve would be unrevealing in this situation. A micro densitometry curve would be the most appropriate way to compare these two situations if one is to make any sort of measurement and proclaim any sort of conclusion. The agitation differences would have changed micro vs macro contrast. By forcing macro contrasts to be equal, the benefits of changes to micro contrast might have been totally lost or enhanced beyond usability.

    I agree with the post by Lee, that the visual impact and appearace (the art if you will) in a photograph is the real test. My point was not in any way the opposite of what Lee said, but rather an extension of what Mr. Gainer claimed to have 'proved' in the quote above. My contention is that by insufficient testing he has not really proven anything quantitatively. Perhaps the pictures do prove something, but the curves do not, as they are the wrong type of measurement. They may have led to the wrong change in the process as well.

    It is like measuring grain and then writing about the speed of the film. Yes, there is a relationship between speed and grain, but they are not locked together and measuring one does not always yield information about the other. It would be like changing development time to get equivalent speeds from a film and then complaining about grain and contrast. Maybe the films are not equivalent in speed. Wrong tests or insufficient tests lead to wrong or inadequate conclusions.

    And why don't I do this type of measurement? I don't compare developers. I use stock developers and methods off the shelf, mostly color, and I don't publish articles in magazines with 'proofs', so although I know how to do it, my personal work and posts here are not directed towards needing proofs. I don't publish new developer formulas. If I did, then I would run a complete battery of tests to verify that they did what I expected them to do. I am merely pointing out possible methodologies that will improve our hobby to those inclined to get into this area. At the same time, I am trying to point out how lack of these tests could lead one to make the wrong conclusion about a process or process condition.

    PE

Page 3 of 10 FirstFirst 123456789 ... LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin