Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,564   Posts: 1,573,464   Online: 782
      
Page 3 of 5 FirstFirst 12345 LastLast
Results 21 to 30 of 45
  1. #21
    Shawn Dougherty's Avatar
    Join Date
    Jul 2004
    Location
    Pennsylvania
    Shooter
    Multi Format
    Posts
    4,139
    Images
    294
    Quote Originally Posted by Bill Burk View Post
    I think part of the reason develop by inspection by dim green light late in the process "works" is... Yes you are exposing the film a little... but you aren't developing it that much longer. So the grains you exposed "to the point of being developable" with the green light, aren't developed for very long.
    My understanding is that the film is desensitized to a degree by the development. Your idea is interesting though, Bill. Have you read about this anywhere?

  2. #22

    Join Date
    Jul 2010
    Location
    Southern USA
    Shooter
    Multi Format
    Posts
    4,069
    The problem with evaluating the negative based on the emulsion side is that you are seeing reflected light only. So you are seeing only the surface of the emulsion, the rest of the emulsion may be undeveloped. Stopping development at this point will lead to thin negatives. This is why the base side is used since if you see a satisfactory image it means that the entire emulsion has been developed. Thus the warning to inspect the base side of the film. Every discussion of the technique that I have read always mentions doing this.

    The idea that the oxidation products of the developer act as a desensitizer is very old. If the effect ever existed it would be dependent on the developing agent(s) used. I seriously doubt that the developing agents used now would have the same effect. The oxidation products of phenolic developing agents like pyrogallol are vastly different from those of a developer like Xtol.
    Last edited by Gerald C Koch; 02-07-2014 at 10:22 AM. Click to view previous post history.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  3. #23
    Shawn Dougherty's Avatar
    Join Date
    Jul 2004
    Location
    Pennsylvania
    Shooter
    Multi Format
    Posts
    4,139
    Images
    294
    Quote Originally Posted by Gerald C Koch View Post
    The idea that the oxidation products of the developer act as a desensitizer is very old. If the effect ever existed it would be dependent on the developing agent(s) used. I seriously doubt that the developing agents used now would have the same effect. The oxidation products of phenolic developing agents like pyrogallol are vastly different from those of a developer like Xtol.
    So do you have any thoughts about how it does work, Gerald? Developed silver helping to block light? The exposure occuring late in the process so not enough time to develop as Bill suggested? Simply too little exposure to make a difference beyond a slight increase in base fog? All of the above?

    I'm just curious. Thanks!
    Shawn

  4. #24
    Thomas Bertilsson's Avatar
    Join Date
    Jan 2003
    Location
    Minnesota
    Shooter
    Multi Format
    Posts
    14,504
    Images
    299
    Quote Originally Posted by Shawn Dougherty View Post
    So do you have any thoughts about how it does work, Gerald? Developed silver helping to block light? The exposure occuring late in the process so not enough time to develop as Bill suggested? Simply too little exposure to make a difference beyond a slight increase in base fog? All of the above?

    I'm just curious. Thanks!
    Shawn
    The article linked to by yourself earlier in the thread was to Michael and Paula's web site, and if I remember correctly they use ABC pyro, which is a pyrogallol developer. I wonder if it makes any difference that it's pyro and a rather heavily staining formula?
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  5. #25
    Shawn Dougherty's Avatar
    Join Date
    Jul 2004
    Location
    Pennsylvania
    Shooter
    Multi Format
    Posts
    4,139
    Images
    294
    Quote Originally Posted by Thomas Bertilsson View Post
    The article linked to by yourself earlier in the thread was to Michael and Paula's web site, and if I remember correctly they use ABC pyro, which is a pyrogallol developer. I wonder if it makes any difference that it's pyro and a rather heavily staining formula?
    That's right, they do use ABC pyro. I watched Paula develop film this way and I've dabbled in it myself. Never noticed any fogging that seemed different than what I'm used to... by eye anyway. I've never measured it with a densitometer. My understanding is that there is only a SLIGHT increase if done properly.

    I'm just curious about what is actually happening. I would LOVE to get some nice IR googles, glass trays with an IR light source underneath them some day.

  6. #26

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    5,010
    It is likely the tanning process which helps slightly. In any case ABC (Kodak D-1) doesn't produce such heavy stain unless you alter the dilution for less sulfite. Kodak later came up with formulas which were designed for more imagewise staining.

    I'll also throw in my white elephant for the fun of it: why anyone would bother in this day and age with DBI versus time/temperature control is beyond me. In the days of Weston it made some more sense because light meters were primitive, and materials were subject to more variability (film speeds, developer activity, etc.). At this point, what value can it possibly add?


  7. #27
    Shawn Dougherty's Avatar
    Join Date
    Jul 2004
    Location
    Pennsylvania
    Shooter
    Multi Format
    Posts
    4,139
    Images
    294
    Quote Originally Posted by Michael R 1974 View Post
    I'll also throw in my white elephant for the fun of it: why anyone would bother in this day and age with DBI versus time/temperature control is beyond me. In the days of Weston it made some more sense because light meters were primitive, and materials were subject to more variability (film speeds, developer activity, etc.). At this point, what value can it possibly add?

    For me that's an easy answer. Catching and fixing mistakes! I make mistakes...

    As far as goggles and IR there is also the cool factor.

  8. #28
    Thomas Bertilsson's Avatar
    Join Date
    Jan 2003
    Location
    Minnesota
    Shooter
    Multi Format
    Posts
    14,504
    Images
    299
    Quote Originally Posted by Michael R 1974 View Post
    It is likely the tanning process which helps slightly. In any case ABC (Kodak D-1) doesn't produce such heavy stain unless you alter the dilution for less sulfite. Kodak later came up with formulas which were designed for more imagewise staining.

    I'll also throw in my white elephant for the fun of it: why anyone would bother in this day and age with DBI versus time/temperature control is beyond me. In the days of Weston it made some more sense because light meters were primitive, and materials were subject to more variability (film speeds, developer activity, etc.). At this point, what value can it possibly add?

    Oh, I agree. But in the same token, a lot of the discussions here are of that nature - interesting but often times not adding much, if any, value to the actual practice of darkroom photography.

    I find that by keeping things as simple as possible, I reach higher and farther with my photography. But it's still interesting to learn, even about things I will never use. It helps paint a bigger picture, and better understand the things I do use, and it throws perspective on those processes that I'm tempted to try, as well as their actual utility.

    And cool factor.
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  9. #29

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    5,010
    Cool factor I'll agree with - but only if you have the goggles.

  10. #30

    Join Date
    Jul 2010
    Location
    Southern USA
    Shooter
    Multi Format
    Posts
    4,069
    True desensitizing dyes greatly reduce an emulsions sensitivity to light . Such dyes as scarlet N and pinakryptol yellow allow a much brighter safelight illumination. So if oxidation products do act as desensitizers their effect is rather small by comparison. The level of illumination used for this development technique is probably too low to have any visible effect on the film provided that exposure is short.
    Last edited by Gerald C Koch; 02-07-2014 at 12:16 PM. Click to view previous post history.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

Page 3 of 5 FirstFirst 12345 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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