Light source for Pyro negs

Discussion in 'Darkroom Developing and Printing' started by Szaboht, Nov 23, 2004.

  1. Szaboht

    Szaboht Guest

    I'm not yet experienced with Pyro development, but I'm considering to give
    it a try. My questions concern the enlarger lamp for pringing pyro
    negatives. I read frequently that a cold light head is best for pyro
    negatives (presumably due to the yellowish stain on the neg), but I have a
    standard tungsten halogen lamp in my only enlarger, an Omega D2 with Super
    Chromega color head. I hope to use VC paper (Forte and Kodak).

    If the spectrum really must be close to that of a cold light head, is there
    a filtration offset that can be dialled into on the enlarger's color head
    to closely simulate the spectrum of a cold light lamp? Or, with regard to
    pringint pyro negs, is the spectral difference between cold light and
    tungsten halogen too small to be concerned about?

    Regards,
    Szabo
     
    Szaboht, Nov 23, 2004
    #1
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  2. The Chromega is perfectly fine.
    You can use the standard Poly Contrast filter values. Or seamlessly adjust
    by varying the Yellow and or Magenta.

    7y + 21m = Grade 2 etc.
     
    Gregory W Blank, Nov 23, 2004
    #2
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  3. Szaboht

    Ken Smith Guest

    Yes I think the spectral difference of the light source would be a
    fairly minor consideration, unless hairsplitting the science is more
    interesting that making pictures to you. The stain of a pyro neg acts
    as a low contrast filter, for the highlights with VC paper. I don't
    think it has any effect on graded paper. The standard tungsten light
    source is contrastier than a cold light, so your move to pyro would
    definitly smooth out the tonal range. I think you'll love the look. My
    landscapes have taken on a far smoother, more realistic and
    atmospheric quality. Enjoy.
     
    Ken Smith, Nov 23, 2004
    #3
  4. Pyro developers produce a stain image that acts to
    intensify the silver image. The printing contrast is higher
    than the visual contrast. The stain image is yellowish and
    blocks blue light. Its effect depends mostly on the spectral
    sensitivity of the paper.
    Most cold light heads are quite blue, although there are
    some that approximately duplicate tungsten light for use
    with variable contrast filters. I think the idea that the
    cold light head is preferable comes from this. However, if
    the paper sees only blue light the spectral output of the
    printing light doesn't matter.
    Now, when variable contrast paper is used with pyro
    negatives there is some tendency for the stain image to act
    as a contrast reducing filter for the highlights. This may
    or may not be desirable since low contast highlights make
    prints look flat. The spectral distribution of the printing
    light will make some difference if VC paper is used the lack
    of green light tending to _increase_ contrast. Note that the
    low contrast filters for variable contrast paper are yellow
    while the high contrast filters are magenta. Yellow blocks
    blue light, magenta blocks green. All this is getting away
    from the point. If you print on graded paper the spectral
    content of the printing light will make little difference
    because the paper has a relatively limited spectral
    sensitivity which is centered in the range where the Pyro
    stain image is most effective.
    Blue cold light heads screw up variable contrast
    filtering anyway. Color heads and condenser heads are quite
    suitable for Pyro negatives. Just don't expect magic. I
    suspect many who rave about Pyro are getting better
    negatives because they are paying more attention to
    controlling all the variables.
     
    Richard Knoppow, Nov 23, 2004
    #4


  5. The 'benefit' of a stained negative is the stain, which takes the
    place of silver density for papers that are sensitive only to blue.
    The stain is yellowish-green, and since these stains block blue light,
    they are seen as extra density by blue-sensitive paper. Variable
    contrast paper DOES see 'green', and so the stain DOES NOT act as
    density for VC papers.

    Use and GRADED paper to get the 'benefits' of pyro. The light source
    does not matter so much. DO NOT use VC paper, because it defeats the
    whole purpose of pyro.

    The stain is without grain and has a nicer gradation of tone than
    silver has, but again, only for graded (blue-sensitive) paper. A
    negative correctly developed in pyro has a rather 'thin' silver base
    which the stain supplements. If the stain were to be removed, the
    silver density of a properly-developed pyro negative would be seen as
    too flat and thin. It's supposed to be that way, because the stain
    assists in providing enough PRINTING density to give a good print.
     
    Uranium Committee, Nov 24, 2004
    #5
  6. Szaboht

    Jim Phelps Guest

    This information is completely wrong.
     
    Jim Phelps, Nov 24, 2004
    #6
  7. This information is completely wrong.[/QUOTE]

    Consider the source,...and I don't mean light. Unless your equating
    light with dimly lit :)
     
    Gregory W Blank, Nov 24, 2004
    #7
  8. No, it's correct!

    FACT: the stain is yellowish-green

    FACT: the stain TRANSMITS yellowish-green and STOPS blue light

    FACT: graded paper is insensitive to green or yellow light

    FACT: VC paper is sensitive to green light

    CONCLUSION: the stain ADDS density as far as graded paper is
    concerned, and DOES NOT add density as far as VC paper is concerned.

    In addition, the green light that the stain allows through softens the
    contrast in the most-heavily-exposed areas, precisely the opposite
    effect that occurs when graded paper is used. Attempting to use VC
    filtration to raise the contrast simply ignores the stain again, and
    you end up fighting against the stain.
     
    Uranium Committee, Nov 24, 2004
    #8
  9. message
    It does add density for the blue sensitive component of
    variable contrast paper but less for the blue and green
    sensitive layer. This has the effect of modifying the
    characteristic curve of the paper. It creates what is
    effecively a shoulder which flattens highlight density. This
    may or may not be desirable. Some claim to get better prints
    this way. It probably depends on the subject matter as much
    as anything else. Essentially, the stain image acts as a
    mild contrast reducing mask when used with variable contrast
    paper.
    When used with graded paper the stain image simply adds
    to the silver image. This is not an advantage or
    disadvantage although it makes measuring the effective
    density of the iamge more difficult since the densitometer
    must have a filter which matches the spectral response of
    the printing material. I am not sure about the validity of
    the idea that the stain image masks grain since it must
    mimic the grain. Any diffusion of the stain away from the
    grains where it is generated would affect resolution and
    sharpness. This is not a common effect of Pyro development.
    Pyro developers also harden or tan the gelatin in a way
    which is proportional to the image density. This effect is
    used to produce relief images for dye transfer and other
    printing methods. In ordinary negatives it sometimes acts to
    increase acutance by modifying the diffusion rate at the
    edges of the image. The hardening itself can cause some
    increase in acutance because of the bending of light at the
    edge where the density of the gelatin is different. This
    differential hardening can also cause minor image
    distortion. This is of no consequence in normal photography
    but precludes the use of staining Pyro developers for
    photgrametry and astrophotography.
    Pyro is the oldest organic developing agent known. It was
    first used by F.Scott Archer C.1865 and has been in use ever
    since. Pyro fell out of use in the 1920's when Metol and
    Hydroquinone developers were devised. These were more
    predictable and more stable. Modern Pyro formulas are
    reasonably predictable but not very stable (PMK seems to be
    an exception). It is not very well known that Pyro
    developers also can be used for paper development to obtain
    warm tones.
    The stain image is not a dye but rather a very stable
    pigment, probably longer lived than the silver image.
     
    Richard Knoppow, Nov 25, 2004
    #9
  10. It is not true that VC paper defeats the purpose of pyro. VC paper with
    blue or magenta filtration makes possible very versatile use of pyro.
    Magenta filtration in small amounts can intensify the shadows. Pyro
    makes possible negatives that can have the high contrast required for
    printing-out papers like platinum and the normal contrast for use with
    VC papers.
     
    PATRICK GAINER, Nov 25, 2004
    #10
  11. Szaboht

    Jim Phelps Guest

    Dimly lit. Yes, it just may be his lights are on but nobody is home...
     
    Jim Phelps, Nov 25, 2004
    #11
  12. It is quite obvious that you have not tried it, and that you have not
    reasoned out the answer that you did not try. The yellow stain is a
    variable density stain. You can bleach out the silver image and leave a
    yellow IMAGE, not a filter layer. This yellow image can be printed on VC
    paper by use of sufficient blue filtering. I have done it, and several
    years ago demonstrated it in an article in Photo Techniques titled "More
    Pyrotechnics" . Certainly, the yellow image is of quite low contrast
    when printed on unfiltered VC paper, but it is there. The yellow part of
    an unbleached pyro negative DOES increase the contrast on VC paper,
    though not as much as on graded paper. If you do the following
    experiment, you will see the fallacy in your reasoning. Develop any
    negative in any non-staining developer to a lower than normal contrast
    index. Make a straight print without filtration on VC paper. Now bleach
    the negative in a rehalogenating solution such as is used in sepia
    toning, and redevelop it in a pyro staining developer. Make a straight
    print from this negative without filtration. Now make another print
    using magenta filtration or a #3 or #4 printing filter. Report to us the
    results if you dare.
     
    PATRICK GAINER, Nov 25, 2004
    #12
  13. Szaboht

    Jim Phelps Guest

    Uranium Committee wrote:

    It is quite obvious that you have not tried it, and that you have not reasoned out the answer that you did not try.

    Pat,

    I believe you have hit the nail on it's head. He has NEVER tried it and is going on his flawed deductive reasoning. I believe in an older post he said something like "... no I have never used pyro but have seen prints from negatives developed in pyro."

    Jim
     
    Jim Phelps, Nov 25, 2004
    #13
  14. Its possible to bleach out either the stain or the
    silver image. The stain can be removed by using a
    permanganate type bleach.
    The stain image, as pointed out Patrick, acts as a
    proportional intensifier. Its density in relation to the
    silver density varies with the type of developer and the
    type of film. The ratio of densities can also be measured by
    making separate readings though the red and blue status
    filters of a color densitometer. The red filter will measure
    the silver image density along, the blue will measure both.
    The important thing is that there is no change in film
    characteristic, i.e., the _shape_ of the exposure vs:
    density curve from Pyro, only a change in its _effective_
    overall slope. You could also prove this by printing on
    panchromatic paper trough red and blue filters.
    In the case of variable contrast paper it is possible that
    the yellow stain image causes a reduction of contrast as the
    density increases. I have never seen actual densitometric
    measurements of this so I can't say whether it is a reall or
    only a claimed effect.
    To be blunt I think Pyro is something of a fad. Pyro was
    the most used developer into the early 20th century but fell
    out of use when other, and better, developers became
    available.
     
    Richard Knoppow, Nov 25, 2004
    #14
  15. Well I am sure that could be among the unwashed masses.

    I've been using Pyro developers since the early 1990's maybe mid 1980's
    well before Gordon Hutchings published his book. There are also
    other photographers who have a much longer history than myself
    Michael A Smith, Steve Simmons probably a whole slue of others.

    I probably would have given up on Pyro had Gordon not devised
    the PMK formula, and had others not made other improvements
    in the Formula aka (Rollo PMK). The fade could be a result of f a
    reinsurgance of interest in the roots of photo, people's interest
    in Alt process as Pyro stained negatives have merits towards those
    applications.

    I personally became interested in Albumen printing and alt process
    as a result of my college history of photo course, I read the Keepers
    of Light and was some what intrigued by some of the old process.

    Around 1988 I did some basic experiments in creating salted prints
    paper negatives, it was a little before you heard so much of people doing such
    things. Its the fun side of photography so I doubt it will readily die out.
     
    Gregory W Blank, Nov 25, 2004
    #15
  16. Szaboht

    Ken Smith Guest


    Richard has often stated that pyro is probably a fad, or people are
    getting good effects because of an increased amount of attention paid.
    All I can say is
    after many years of regular developers, resulting in highly diluted
    developers to control landscape contrast, I tried pyro (cat) and was finally
    happy with the look of things. I could maintain alot of shadow detail,
    yet still have a nice atmospheric sky, even though the exposures
    usually favor the shadow. My skies would often white out with regular
    developers. Less dev. times and the scene goes flat and looks like
    a compensating developer or preflash was used.

    The powerful Ansel Adams look often settles for darker shadows, as the
    image made is more theatrical than I'm making. Weston too, has than
    drama. I'm more interested in how the eye sees the contrast, and
    really have to fight for longer tones. Although they both have many
    shots where it all comes together, I tend to think thats due to lighting
    conditions more than anything else.


    With my dev. time using pyrocat, I have found where I can get a long
    tonal range while still maintaining a perfect contrast. Never flat
    looking and IMO more natural looking than regular developers. If I
    want the punchier graphic look, I stick with D-76, but pyrocat
    definitly yeilds a unique and natural looking image. More like what
    the eye sees. 1:100 Rodinal, highly diluted HC-110, etc, will deaden
    into flatness if I reduce the development enough to hold the high
    areas the way the pyro does. I would say that because I give a full
    shadow exposure, even in contrasty light, my highs get way up there,
    so the stain allows good printability but is still a pleasing white.
    Detail without drabness.

    Ken Smith
     
    Ken Smith, Nov 25, 2004
    #16
  17. Pyro does have advantages for those who would like to be able to use the
    same negative for either printing-out processes that require high
    contrast but are only blue sensitive or printing with VC paper. There
    are also advantages claimed for wide range scenes that include clouds.

    I have been privileged to have a compilation of the papers of Hurter &
    Driffield who considered and experimented with inorganic developer and
    organic pyrogallol. They never made much of the staining by pyro, using
    enough sulfite to pretty well eliminate the stain.

    My point, with which I think you agree, is that the effect of the pyro
    stain when properly done is to increase the contrast even with VC paper,
    though not as much as with graded paper, and to present some experiments
    to demonstrate it. I do not use a lot of staining developer, but do
    occasionally use it as an intensifier to increase contrast of
    underveveloped negatives. I guarantee it works, and the process may be
    repeated. Each repetition restore the original silver density and adds
    to it a proportional stain.
     
    PATRICK GAINER, Nov 25, 2004
    #17
  18. True, but that was before PMK, which turned pyrogallol based developers into a
    reliable method of development. Our gratitude to Patrick Gainer for that.


    Francis A. Miniter
     
    Francis A. Miniter, Nov 26, 2004
    #18
  19. Patrick? Is there some connection between our Patrick and
    Gordon Hutchings work that I am unfamilar with, of course there
    could be because I don't pretend to know all, but now I am curious.
     
    Gregory W Blank, Nov 26, 2004
    #19

  20. That's the problem with rushing. I meant Gordon Hutchings and had just looked
    at Patrick's name in a previous post. Sorry.


    Francis A. Miniter
     
    Francis A. Miniter, Nov 26, 2004
    #20
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