Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,536   Posts: 1,544,118   Online: 949
      
Page 1 of 3 123 LastLast
Results 1 to 10 of 21
  1. #1

    Join Date
    Mar 2004
    Location
    Southern California
    Shooter
    Multi Format
    Posts
    3,879
    Images
    11

    Howard Bond on Pyro - again

    The following is a direct (and complete) quote from Howard Bond’s article, “Pyro Effects, Further Tests Show More, But Still Limited Effects” published in Photo Techniques, September/October 2004.

    Conclusions
    Preparation of this article has shown me that pyro does indeed produce less-visible grain and greater edge sharpness, although the latter may not be apparent in moderate enlargements and with some subjects. I understand why pyro’s depression of high values appeals to photographers who are determined to use Tri-X, in spite of the lower contrast in the shadows inherent in its curve shape. I don’t see how users of films with rather straight characteristic curves – such as T-Max, FP4+, HP5+ and Delta 100 – can embrace pyro, because of its depression of high values and loss of local contrast there. I have also become aware of a big obstacle to the comparison of two photographs of a subject when one negative is developed in pyro: there is no way to know what fraction of the stain is acting as a VC filter and what fraction is acting as neutral density. This makes it impossible to know what density range the pyro negative should have to match the other negative.

    The fact that famous photographer A used pyro and made remarkable photographs is not a reason for choosing pyro. One can easily cite famous photographers B, C and D who used or are using other developers. No doubt all of them could switch developers and still make remarkable photographs.

    Now that I am better acquainted with pyro, and since I don’t use Tri-X, I see ample purely photographic reasons for ignoring it. There is no need to take into account the fact that 2 grams constitutes a fatal dose or the concern of my biochemist friends that pyro may destroy dopamine producing brain cells.


    The first two paragraphs show me that in spite of his latest efforts, Howard is still “out in the weeds.” He clearly still doesn’t grasp the real technical issues.

    Howard’s last paragraph really annoys me. “There is no need to take into account the fact that 2 grams constitutes a fatal dose…”

    Overlooking for the moment that Bond cites no scientific data to support this human toxicity speculation, it implies that one would need to ingest an enormous amount of PMK Pyro working solution (at least 2 liters) if one were bent on pyro induced suicide by drinking PMK. In the process of drinking 2 liters of PMK, one would also consume 12 grams of sodium metaborate, plus 0.2 grams of Metol and 0.4 grams of sodium bisulfite. Then, of course, there are all the oxidation products, etc.

    If you drank 2 liters of one of Bond’s favorite developers, D-76 (diluted 1:1), you would consume: 5.0 grams of Hydroquinone - a very close (and toxic) benzene ring relative of pyrogallol, plus 100 grams of sodium sulfite, 2 grams of Metol and 2 grams of Borax.

    When working with photographic chemistry, always practice chemical safety!

    Protect your skin, mucous membranes and eyes!

    Protect your respiratory system!

    Don’t ingest any of the processing solutions!

    Oh, by the way: "...pyro may destroy dopamine producing brain cells"

    Gee, I always thought that was the Amidol myth...
    Tom Hoskinson
    ______________________________

    Everything is analog - even digital :D

  2. #2

    Join Date
    Mar 2004
    Shooter
    Multi Format
    Posts
    965
    Images
    58
    It also amazes me that a man can manage to get published for his "analysis" of a developer, but argues that one cannot make a direct comparisson of Pyro vs. D-76 due to VC paper.

    For cying out loud, man, have you never heard of GRADED PAPER?????

  3. #3

    Join Date
    Sep 2002
    Shooter
    Large Format
    Posts
    4,530
    There is no need to take into account the fact that 2 grams constitutes a fatal dose…”
    I wonder, is this 2 gr/kg? if so then it is way more than a couple of liters of developer one has to ingest.

    I have not read the complete article and when it gets here I dont think I will get the magazine. PT is fast becoming another digital magazine, and the Pyro debate has become stale IMO, if you like it use, if you dont then dont, no big deal....IMO.

  4. #4
    c6h6o3's Avatar
    Join Date
    Oct 2002
    Shooter
    Large Format
    Posts
    3,179
    Images
    6
    Quote Originally Posted by Tom Hoskinson

    1) Preparation of this article has shown me that pyro does indeed produce less-visible grain and greater edge sharpness,

    2) The fact that famous photographer A used pyro and made remarkable photographs is not a reason for choosing pyro.
    1) In my experience, this is self contradictory. Pyrogallol based developers with no metol produce dramatically sharper negatives precisely through the mechanism whereby grain visibility is actually enhanced. In other words, the penalty one pays for greater edge sharpness (acutance) is more grain. This is virtually a proverb among those of us on APUG who have used ABC pyro extensively. By the same token, in a Pyro-Metol-Kodalk (PMK) formula, grain is masked by the exact mechanism which softens edge sharpness. The metol "smears" the silver halide crystals somewhat. You can't have it both ways.

    2) I must agree. But, the fact that great photographers, famous or not, made remarkable photographs with pyro is a good reason for trying it. After they try it, most serious photographers seem to then find the good reasons for choosing it.

  5. #5
    Dave Miller's Avatar
    Join Date
    Dec 2003
    Location
    Middle England
    Shooter
    Medium Format
    Posts
    3,894
    Images
    2
    I rather get the impression that Tom's not impressed!
    Regards Dave.

    An English Eye


  6. #6

    Join Date
    Mar 2004
    Location
    Southern California
    Shooter
    Multi Format
    Posts
    3,879
    Images
    11
    Quote Originally Posted by Dave Miller
    I rather get the impression that Tom's not impressed!
    Quite right Dave!

    I am impressed by logical reasoning processes that lead to well designed experiments which produce useful data.

    I see no evidence of that in either of Howard Bond's pyro articles.
    Tom Hoskinson
    ______________________________

    Everything is analog - even digital :D

  7. #7

    Join Date
    Sep 2002
    Shooter
    Large Format
    Posts
    4,530
    Quote Originally Posted by Tom Hoskinson
    Quite right Dave!

    I am impressed by logical reasoning processes that lead to well designed experiments which produce useful data.

    I see no evidence of that in either of Howard Bond's pyro articles.
    Well, Kirk and Sandy have been going round and round just to agree on what kind of densitometer and what values should be used when testing staining developers with a step tablet. These are two knowledgeable people and they cant seem to reach an agreement. Methinks designing a good experiment and publish it will always leave someone unhappy. Is the debate really worth it?

    To add another kink to this, how about doing a test of unsharp mask vs stand development. From what I have heard those who practice SD seem to swear by it and the sharpness it produces.

  8. #8

    Join Date
    Sep 2003
    Location
    Düsseldorf, Germany
    Shooter
    8x10 Format
    Posts
    1,021
    Images
    1
    I get the impression, on reading the article, that Monsieur Bond did not expose as much as I would expect in order to make educated and experienced decisions about any film-dev combo. What are people's opinions about this? I believe testing in the lab is one thing and it is another to actually expose the film-dev combo to real-world variables (i.e. wind, water, shake, timer, agitation, etc, etc, etc.). How many sheets does one need to expose before a conclusion about the combo can be made? In my case, my first 100 sheets of Efke PL100 did not close the deal for me with Pyrocat HD. I merely saw its potential. I nearly gave up because of Efke's extreme fragility. My guess would be between 100 to 150 sheets of real world photographs qualifies someone to make informed, PUBLISHED decisions about whether a fil-dev combo is useful or not. I sincerely hope that Monsieur Bond did just that amount - but I suspect otherwise.
    Francesco

  9. #9

    Join Date
    Sep 2003
    Location
    Düsseldorf, Germany
    Shooter
    8x10 Format
    Posts
    1,021
    Images
    1
    Quote Originally Posted by Jorge
    To add another kink to this, how about doing a test of unsharp mask vs stand development. From what I have heard those who practice SD seem to swear by it and the sharpness it produces.
    Jorge, I do not own a densitometer (anymore - sold it 6 years ago). I did want to compare my normal agitation procedure (i.e. continuous but gentle tube agitation) versus minimal agitation (a less extreme form of semi-stand dev). I was convinced to try this by people who swear by SSD, partly to make my own conclusions and partly to, hopefully, prove them wrong. My test was very simple: expose two sheets for each scene, develop one using my normal way, the other using minimal agitation. I have about 70 pairs of 8x10s for comparison. Well, you know my motto all too well "one neg, one shot". And you also know which agitation method I have settled on. I am not much bothered by apparent sharpness issues, althought that is there too. I was more interested in which method produced the better local contrast. For me, the only way to find this out was to use up film and then print both to compare. This is the kind of data I like to see people come up with when they compare film-dev combos.
    Francesco

  10. #10
    David A. Goldfarb's Avatar
    Join Date
    Sep 2002
    Location
    Honolulu, Hawai'i
    Shooter
    Large Format
    Posts
    17,284
    Images
    20
    I liked the chickens. You can't argue with the chickens.

Page 1 of 3 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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