Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 68,693   Posts: 1,482,434   Online: 915
      
Page 18 of 24 FirstFirst ... 812131415161718192021222324 LastLast
Results 171 to 180 of 232
  1. #171
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,710
    Images
    65
    Quote Originally Posted by Hologram View Post
    Post-swelling the emulsion with sorbitol is probably a better solution than doing it with glycerin. But both may leave the surface somewhat tacky. Citric acid might be even more convenient.

    Yes, "streak" may be a pretty good translation for Schlieren.
    I have been thinking about the use of Citric Acid. This treatment might be harmful. IDK, but emulsions for the most part are at a neutral pH, say around 5.5 - 6.5. Citric Acid could begin to degrade the gelatin. Urea might be better for swelling the gelatin, if that is what you want. For an adhesive, Sorbitol, Glycerin, and other similar chemicals would probably be preferred.

    The Schlieren observed is not Nebel, but streaks could be caused by fog and thus be stated that way in the original text as a description of fog (Nebel).

    PE

  2. #172

    Join Date
    Oct 2006
    Shooter
    Medium Format
    Posts
    131
    Quote Originally Posted by holmburgers View Post
    Thanks,

    I think my Sorbitol solution is 70% (I'll have to check). How should I compensate for the difference? Is there a standard conversion, something to go off of?

    I'It depends on how much wavelength shift you get. I'd start with 5-10% solutions.

  3. #173

    Join Date
    Oct 2006
    Shooter
    Medium Format
    Posts
    131
    Quote Originally Posted by Photo Engineer View Post
    I have been thinking about the use of Citric Acid. This treatment might be harmful. IDK, but emulsions for the most part are at a neutral pH, say around 5.5 - 6.5. Citric Acid could begin to degrade the gelatin. Urea might be better for swelling the gelatin, if that is what you want. For an adhesive, Sorbitol, Glycerin, and other similar chemicals would probably be preferred.
    I agree that citric acid may attack a not well hardened gelatin layer. But in my experience (limited to holographic/Lippmann emulsions only) urea is far more aggressive than citric acid.

    Generally speaking, I guess better than doing post-swelling would be to have a more "conservative" approach:
    - pre-harden the layer prior to processing;
    - use a well-balanced colloidal developer (excess of thiocyanate results in loss of silver halide, producing a wavelength shift);
    - dry the layer in ethanol or isopropanol.

    Quote Originally Posted by Photo Engineer View Post
    The Schlieren observed is not Nebel, but streaks could be caused by fog and thus be stated that way in the original text as a description of fog (Nebel).
    Right. Moreover, again according to Neuhauss, removing all the mercury from the emulsion after exposure seems to have been a messy business.

  4. #174
    holmburgers's Avatar
    Join Date
    Aug 2009
    Location
    Rochester NY (native KS)
    Shooter
    Multi Format
    Posts
    4,400
    Images
    2
    Man... I look back at my posts from nearly a year ago saying, "I'm gonna do it soon!" HAH! What a schmuck I was...

    But such is life.

    In this post by Mssr. Shaffer, he used a glyoxal pre-hardener and his results suggest that it was necessary.

    I've got chrome alum, so I'm thinking to try a 3% solution for 4 min. Then proceed to develop with a 2-part GP-2 developer, followed by a wash. I've also got some sorbitol incase it needs to be post-swelled.

    Anyways, first time using a hardener so just want to make sure that sounds like a good % and time.

    Cheers y'all

    edit: Oh, and is a wash after the hardener necessary or would it be detrimental?
    If you are the big tree, we are the small axe

  5. #175
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,710
    Images
    65
    Use 10% chrome alum for 5 mins with a 5 min wash.

    PE

  6. #176
    holmburgers's Avatar
    Join Date
    Aug 2009
    Location
    Rochester NY (native KS)
    Shooter
    Multi Format
    Posts
    4,400
    Images
    2
    Thanks PE... I was way off.
    If you are the big tree, we are the small axe

  7. #177
    holmburgers's Avatar
    Join Date
    Aug 2009
    Location
    Rochester NY (native KS)
    Shooter
    Multi Format
    Posts
    4,400
    Images
    2
    http://www.ilfordphoto.com/holofx/holofx.asp

    A possible development in the Lippmann world (and what a vibrant world that is! ). The question is, are they suitably panchromatic?

    Available for sale at freestylephoto.biz. Prices are pretty high, but only $4.5 per 2.5"² plates.
    Last edited by holmburgers; 06-17-2011 at 11:24 AM. Click to view previous post history.
    If you are the big tree, we are the small axe

  8. #178
    BetterSense's Avatar
    Join Date
    Aug 2008
    Location
    North Carolina
    Shooter
    35mm
    Posts
    2,749
    That link doesn't work for me.
    f/22 and be there.

  9. #179
    holmburgers's Avatar
    Join Date
    Aug 2009
    Location
    Rochester NY (native KS)
    Shooter
    Multi Format
    Posts
    4,400
    Images
    2
    fixed it

    thanks
    If you are the big tree, we are the small axe

  10. #180
    holmburgers's Avatar
    Join Date
    Aug 2009
    Location
    Rochester NY (native KS)
    Shooter
    Multi Format
    Posts
    4,400
    Images
    2
    So, over the weekend I finally shot and developed a plate. I've got photos that I will post this evening, and although I haven't been able to successfully view interference colors, the whole thing is nonetheless fascinating and quite unlike any other silver-halide film I've ever dealt with.

    It was late last night, so it's possible that diffuse sky-light will aid in seeing the colors.

    One thought that helped to reinvigorate my interest in interference "heliochromy" was learning about first (or front) surface mirrors. http://en.wikipedia.org/wiki/First_surface_mirror

    You can buy these mirrors for reasonable prices (http://howardglassco.thomasnet.com/v...bc=100|3001011) and you can actually make them yourself quite easily from a cheap mirror.

    It seems to me that if you coated these plates with a Lippmann emulsion, all conditions of "optical contact" between mirror & emulsion would be met.

    Now, the thing that has me wondering is whether or not you can just leave the emulsion on the mirror during processing & for viewing. There seems to be some disagreement, or at least a lack of clear concensus on this.

    J.S. Friedman in the History of Color Photography clearly states that the mirror must be present for viewing, and that this is of course difficult with mercury. However, people here on APUG have seen Lippmanns where their very own eyes, and with no reflector present. Furthermore, an old post on the holo-wiki archive has a discussion wherein FSM's are mentioned, but people seem to be saying that the emulsion needs to be removed from this for viewing.

    So who the heck knows?!

    Let's try to figure this out... because this seems like a home-run technique for modern day Lippmann photography.
    If you are the big tree, we are the small axe



 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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