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  1. #11
    gainer's Avatar
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    I have a 23C and a 6X7 Chromega side by side. I believe the quartx halogen bulb has a higher color temperature than the 111. There is not usually very much difference between the two without filter, even though one is condenser. On the Chromega I seldom use anything but magenta for higher contrast, while I use Ilford filters on the 23C. I can't relate the mount of magenta exactly to contrast grade, but sometines I use quite a lot on stained negatives. Other times, I use 15 to 30 magenta to increase contrast in the shadows. The stain, being proportional to the silver, overpowers the magenta somewhere up the line and renders the highlights nicely.
    Gadget Gainer

  2. #12

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    Quote Originally Posted by Donald Miller
    Sandy,


    As I read your curves they indicate that Pyrocat does offer better tonal separation throughout it's curve by virtue of the shorter toe and the absence of the shouldering indicated with PMK.

    Did you do any work on the issue of stain color in the compression of highlight tonal scale between PMK and Pyrocat when used with VC materials and the effects of the stain color as it effects the colors of VC filters?
    Donald,

    I did not do any specific work on the issue of stain color, but in general I agree with Barry Thornton's observations (in Edge of Darkness) about the printing difference with VC papers between the yellow stain of PMK, which serves to low the printing contrast on VC papers, and the brown tone of pyrocatechin type developers (Diaxactol, Pyrocat-HD). Brown stain also lowers the overall contrast but it causes less highlight shouldering and can therefore be compensated for by increasing time of development. Yellow stain is more insidious because the longer you develop the more shouldering you get, and so the compression/compensation, instead of starting around Zone VIII, will start in Zone VI or VII with longer time of development. There are some type of subjects that will benefit from this type of compression, for example, shooting interiors with bright light streaming through, or shooting a scene in the sun with side by side white an black objects which both require texture.

    We also have to consider the film. It would be counter-productive to use a film with a tendency to shoulder, say HP5+, with a developer that produces a lot of compression in the highlights. This would give you very muddy highlights. So PMK and HP5+ on the fact of it appears to me to be a very poor combination. On the other hand, some films have a tendency to do the opposite, i.e. not compress at all in the shoulder but flare upward. Tri-X 320 is such a film and practice shows that it works very well with PMK as the developer compression counters the flaring shoulder and helps to hold texture in the upper highlights.

    But in any event, the point here is that there are important differences between these two developers that need to be considered, of which the most important is the way they render highlight detail. Overall, and just looking at the results with the FP4+ film, here is what I would say about the print curve that was attached earlier.

    1. PMK gives slightly better separation in Zones I and II, while the transition with Pyrocat-HD is more gradual, but texture extends deeper into the shadow because of the slight increase in EFS.

    2. Tonal values are rendered about the same in Zones III through VI.

    3. Separation is much better with Pyrocat-HD in Zones VII and VIII.

    4. Separation is much, much better with Pyrocat-HD in Zone IX and above, but with certain kinds of subjects the compensation of PMK will allow you to print these values whereas some burning in might be required with Pyrocat.

    In general I would say that Pyrocat-HD renders tonal values more in a way that is seen with traditional high definition semi-compensating developers such as FX-2, whereas PMK (and Rollo Pyro) are rather unique for their extreme compensation/compression.

    Obviously some of my comments are speculation, albeit informed speculation based on concrete data.

    Sandy
    Last edited by sanking; 01-01-2005 at 12:47 PM. Click to view previous post history.

  3. #13

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    Quote Originally Posted by sanking
    Kirk,

    Plain old H&D curve stuff. The x-axis, along the horizontal, corresponds to values of exposure expressed in relative logE values, which means that the numbers are in correct proportion to each other but do not corresopond to any specific standard of measurment. The y-axis, on the vertical, relates to values of image density, also in log values, that corresond to the common log of opacity.

    Sandy
    OK - I just wanted to make sure that you weren't doing something more advanced, like trying to do a tone-reproduction graph.

    So Graph 1 is of the negs with expsoure on the x and blue channel neg density on y.

    And Graph 2 is print density on VC paper on y. Is it neg density in blue channel on x? Also, is this of the 0.51 CI negs?

    Could you supply the graph of the negs on the Grade 2 paper for comaprison? And also the 0.51 negs on grade 2.

    The Pyrocat neg in graph 2 looks a little flat compared to the PMK in the middle tones - how about a graph of the Pyrocat @ grade 5 and the PMK at say grade 4 so the graphs have a more similar slope.

  4. #14

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    Quote Originally Posted by Kirk Keyes
    OK - I just wanted to make sure that you weren't doing something more advanced, like trying to do a tone-reproduction graph.

    So Graph 1 is of the negs with expsoure on the x and blue channel neg density on y.

    And Graph 2 is print density on VC paper on y. Is it neg density in blue channel on x? Also, is this of the 0.51 CI negs?

    Could you supply the graph of the negs on the Grade 2 paper for comaprison? And also the 0.51 negs on grade 2.

    The Pyrocat neg in graph 2 looks a little flat compared to the PMK in the middle tones - how about a graph of the Pyrocat @ grade 5 and the PMK at say grade 4 so the graphs have a more similar slope.
    Yes, Graph 1 blue channel exposure on x-axis.

    Can supply the graphs of the .52 CI negative. Will do so later.

    The Pyrocat neg in graph 2 has the same CI as the PMK negative. The slopes are virtually identical for the two negatives.

    Sandy

  5. #15

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    Quote Originally Posted by Kirk Keyes

    Could you supply the graph of the negs on the Grade 2 paper for comaprison? And also the 0.51 negs on grade 2.
    Attached is the graph for the 0.51 (actually 0.53 and 0.54) negatives, based on analysis from blue channel reading.

    I did not do a graph of these negatives on VC paper with the #2 filter since the contrast was so obviously off, and I appear to have discarded the contact prints that were done with this set of negatives with the #5 filter. However, the results were almost identical in terms of overall contrast to the CI .70 negatives made with the #2 filter.

    Sandy
    Attached Thumbnails Attached Thumbnails NegCurve#2.jpg  
    Last edited by sanking; 01-01-2005 at 08:55 PM. Click to view previous post history.

  6. #16

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    Sandy, if you have the time and energy, I'd like to see a comparision between Pyrocat HD, PMK and Wimberly's WD2D (with and without the "+"). Ah, no hurry!

  7. #17
    Eric Rose's Avatar
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    Jim why don't you do it yourself and let us all know the results. Sandy I think was spurred on to do this round of testing because of some very general comparisons of PMK and HD done elsewhere.
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  8. #18

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    Quote Originally Posted by EricR
    Jim why don't you do it yourself and let us all know the results. Sandy I think was spurred on to do this round of testing because of some very general comparisons of PMK and HD done elsewhere.
    The reason for the tests was somewhat more specific. Someone on the pure silver list, who previously had taken UV readings of a PMK negative with a spectraphotometer, asked me to do the same with a Pyrcocat-HD negativeb. His premise was that these readings, if different, would suggest that PMK and Pyrocat-HD negatives would print differently on VC paper. I did not have time to have the test done, but thought, why not just test this directly with negatives made with the two developers? So I looked through my file of negative tests and found PMK and Pyrocat-HD negatives that closely matched in terms of CI in blue channel reading. The rest was pretty routine.


    Sandy

  9. #19
    Eric Jones's Avatar
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    Looking at the graphs just above the name of each developer there are two boxes, one reads 100++ for Pyrocat and 64+ for PMK. Now I am assuming they are the speed of the film in this particular developer, agitation technique, etc. But, I was wondering what the (+) signs mean? Perhaps, 100++ is actually 100 + 2/3 stop and 64+ is 64 + 1/3 stop? Thanks for any additional info.

  10. #20

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    Quote Originally Posted by Eric Jones
    Looking at the graphs just above the name of each developer there are two boxes, one reads 100++ for Pyrocat and 64+ for PMK. Now I am assuming they are the speed of the film in this particular developer, agitation technique, etc. But, I was wondering what the (+) signs mean? Perhaps, 100++ is actually 100 + 2/3 stop and 64+ is 64 + 1/3 stop? Thanks for any additional info.
    That is also my understanding about the meaning of the + signs. I don't have my WinPlotter manual on hand at the time, and honestly don't remember what it says about this, but I have always understood it to be as you suggest.

    However, these tests were not conducted to test film speed so the comparison numbers are not necessarily a true indicator of EFS of the two developers.

    Sandy

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