Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,226   Posts: 1,532,679   Online: 831
      
Page 1 of 8 1234567 ... LastLast
Results 1 to 10 of 77
  1. #1

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,609

    Altman/Henn: Effect of Developer Composition on the Structure of Photographic Images

    Would anyone be interested in discussing this study (summarized in Haist)? I can list the developer compositions if people don't have access to Haist or the original study.

    There are some things I'd like to discuss in the results that seem odd. Also, does the experiment not seem to have too many variables to manage at once? Actually one of my questions is - does anyone know how I could get a copy of the original paper? The summary in Haist is not very detailed when it comes to the procedures used.

    It would be interesting to redo such an experiment with some current films. It could potentially explode some myths.

    Michael

  2. #2
    piu58's Avatar
    Join Date
    May 2006
    Location
    Leipzig, Germany
    Shooter
    Medium Format
    Posts
    587
    Dear Michael,

    I don't konow the Altman paper but I am interested in reading more oft it. In the net I could not find anything.

    Some of the effects are well known
    - High content of sulfite reduces the grain but gives less sharpness (the grain itself is not sharp)
    - Diluted developer works slightly grainier but sharper (this is the sulfite effect)
    - Developers without redox system give sharper images because auf the edge effect. Well known types are Rodinal and CG 512 / Rollei RLS
    - Very diluted developers give weak highlights: The developer gets exhausted before.
    - Bromide inhibits devlopment with most of the developing agents: Bromide reach developers give more contrasty images and cleaerer highlights if you develop a positive image. Bromide acts more if you agitate less.

    In my younger years I learned boundary layer chemistry (but not photographic chemistry). Most of the effects can be explained and understand.
    ---
    Uwe Pilz

  3. #3

    Join Date
    Aug 2005
    Location
    Los Alamos, NM
    Shooter
    Multi Format
    Posts
    2,044
    I was unaware of the paper, but I have been quite aware of the subject. I'd certainly like to find out more about it. Newer films seem less subject to variation with different developers, so perhaps the members could update the study a bit.

  4. #4

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,609
    piu58 - those are the general rules, but the Altman/Henn study has some rather curious results. If nothing else the study suggests it is more difficult to generalize than we might think, and that with a given film a developer modification might yield unexpected results. This would tend to support the notion (as PE has mentioned before) a developer can indeed be "optimized" for a given film - but probably for only that film.

    nworth - I'll put together a summary and post it along with some of my questions/notes. Some of the results they got are quite surprising.

  5. #5

    Join Date
    Feb 2006
    Location
    Hawaii
    Shooter
    35mm RF
    Posts
    710
    Yes please

  6. #6
    juan's Avatar
    Join Date
    May 2003
    Location
    St. Simons Island, Georgia
    Shooter
    Multi Format
    Posts
    1,637
    Images
    4
    I'm interested, too.

  7. #7

    Join Date
    Aug 2006
    Shooter
    Multi Format
    Posts
    325
    I have a copy of the paper, and will be glad to answer specific questions about it, or type small excerpts or tabulated data from it.

    I don't know if it's much use, other than for the historic value. Here's something the authors said:

    Previous work carried out in these Laboratories had shown that the comparative effects of two developers were not the same for all emulsions, which means that it is not possible to generalize with respect to such results. Therefore, tests were carried out on the three Kodak black-and-white emulsions then available for 35mm amateur photography: Kodak Panatomic-X Film, Kodak Plus-X Film, and Kodak Tri-X Film.
    The tests were done prior to 1960, so those films are over 50 years in the past.

    Richard Henry also did somewhat similar, more recent tests (mid 1980's), described in Controls in Black-And-White Photography.

  8. #8
    piu58's Avatar
    Join Date
    May 2006
    Location
    Leipzig, Germany
    Shooter
    Medium Format
    Posts
    587
    I have Controls in Black-And-White Photography 2nd edition. Very valuable book! Richard was a retired chemist with much of time and much of very high end measurement equipment. He analysed nearly effery effect known in photgrapy with scientific methods.
    ---
    Uwe Pilz

  9. #9

    Join Date
    Aug 2006
    Shooter
    Multi Format
    Posts
    325
    Yes, I'm still astounded at how much Henry did!

    I see in Haist that the discussion of this paper (Altman-Henn)starts on about page 415. Haist gives the pertinent tables: the exact developer formulations as well as the results. It seems like most of the significant results are there, so I'm wondering what Michael's questions would be.

    Q. First question might be, why do the formulas vary, beyond what is the aim of testing? For example, in the first formula set, they intend to vary only (sodium) sulfite, at 10,30,100, and 200 g/l. Yet they also vary bisulfite and Kodalk.

    A. They say that the base formula, AH-3, is essentially D-25. Since different amounts of sulfite would change the solution pH, and activity, the adjustments were made in the interests of "maintenance of approximately constant activity..."

    Q. Next question might be, how were the different developing times determined, and why do the resulting gammas vary?

    A. They say, after the formulas were decided on, "complete time-gamma studies were made, and times of development at 68 deg F for a gamma of 0.65 for all emulsion-developer combinations were chosen."

    My best guess is that, even though the final result (gamma) varied, they decided to stay with their original plan. Note that the data tables are foot-noted "All data from single runs, except..." sample AH-1 was average(5 runs) and the D-76 (1:1) reference was average(2 runs).

    Q. How were the test films processed?

    A. The say, "Accutance, granularity, and sensitometric-control strips were then exposed and processed for the times indicated by these studies. Processing was in the sensitometric machine of Jones, Russell, and Beacham, which gives strong and uniform agitation."


    I hope this is a good start as I probably won't be around when questions start.

  10. #10

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,609
    I'm still working on the summary because I want to present the formulas for those who don't have Haist. But as quick start - @ Mr Bill: Yes the first Q was one of mine too. I reasoned it was to maintain approximately the same pH (as particularly in the acutance formulas without the addition of metaborate some of the formulas would have had extremely low activity. But I was hoping they listed the resulting pH values in the original paper as they are not in Haist. I have other questions on this because some of the resultant developing times seem odd.

    Another thing - if one really wanted to isolate the effects of sulfite and metol concentrations, would it not have been better to change only one variable at a time? For example, if you keep the concentration of Metol constant and vary the sulfite concentration, if you adjust the pH to maintain activity, you are only testing for the effect of the amount of sulfite. If one then kept the sulfite concentration constant and varied the pH, you could test for increased solvent activity in relation to developing time. Etc.

    I was ok with the Gamma targetting, even with the small variations.

    I have some more questions regarding the methodology, and then would like to highlight some of the rather surprising results.

    Will get this posted today.
    Last edited by Michael R 1974; 12-19-2012 at 07:27 AM. Click to view previous post history.

Page 1 of 8 1234567 ... LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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