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: 1,482,431   Online: 840
      
Page 8 of 13 FirstFirst ... 2345678910111213 LastLast
Results 71 to 80 of 124
  1. #71
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,710
    Images
    65
    I saw a "hand held" X-Ray fluorescence analyzer on Wednesday that was attached to a simple microscope. Image the film and then point the analyzer at the spot, which is about 1mm square or less, and you get the amount of whatever metal you are looking for be it Silver, Mercury, Lead etc.... These units cost a bit, but are so easy to use that anyone can now do QC on their hand coatings. Well, I don't think we need one of these, but I mention it to show it is possible. No radiation license is needed AFAIK.

    PE

  2. #72

    Join Date
    Jun 2004
    Location
    Portland, OR
    Shooter
    4x5 Format
    Posts
    3,268
    Ron - all the hand held X-Ray Fluorescence meters I've seen (about the size of an old Geiger counter) need certifications for use. They usually have a radioactive isotope as the source of the x-rays.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  3. #73
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,710
    Images
    65
    Could be. This one was about 1.5x the size of a Hanna pH meter. You know the ones I am referring to. Pretty small unit. It was connected to a power supply that was out of sight from me. The cable was not very large in diameter. It had 2 radiation trefoils on it that I assumed were there due to the X-rays rather than to a radio-isotope. I should have thought to check.

    PE

  4. #74
    Mustafa Umut Sarac's Avatar
    Join Date
    Oct 2006
    Location
    İstanbul - Türkiye
    Shooter
    35mm RF
    Posts
    3,411
    Images
    104
    I think these are work as handheld x ray spectrometers. No need of certificates , source is semiconductor.

  5. #75
    dwross's Avatar
    Join Date
    Feb 2004
    Location
    Oregon Coast
    Shooter
    Multi Format
    Posts
    785
    Quote Originally Posted by Kirk Keyes View Post
    I don't think any one person, or even a small group of people will be able to match the level of technology that is in todays commercial color film products. But we as home emulsion makers can still make marvellous papers and B&W film/plate emulsions.

    We just can't compete with the amount of applied science that goes into these things. Which one of us is going to spend the hundreds of thousands of dollars for equipment and get the radiation licenses needed to make and operate a silver content meter to measure the amount of silver that is applied to our film as we run our home make emulsion coater?

    But we can still do great things, as individuals and through groups like this.
    Kirk,

    Thank you for putting things into perspective so eloquently (and for the workshops plug ). I can't add much to the core of your statement, but I will give a try at an addendum. I was busy all day yesterday with a back-breaking, braindead, non-photography task, and had nothing but time to think about the situation here.

    It's long been a puzzle to me that Ron continues to make basic emulsion making into a task that is beyond reach of mere mortals. There seems to be a resistance to evidence that defies the facts -- that gorgeous, extremely useful emulsions are being made, today, with today's materials and knowledge. And, it doesn't take a chemistry degree, professional lab equipment or a big budget. The embryonic cynic in me has wanted to blame it on trying to prime the pump for book/DVD sales (whenever that may be). Yesterday, I came to a more charitable viewpoint -- at least for Ron, if not for Kodak.

    George Eastman started Kodak right out as a monopoly. Not only was commercial competition aggressively, and sometimes ruthlessly, quashed, but so too was 'competition' from do-it-yourself'ers. The motto of "you push the button, we do the rest" was there from the beginning. Kodak pushed a corporate philosophy of infantilizing its customers, with a brilliant campaign that involved both carrot and stick. After what is literally now generations of the honing of that philosophy, how can an engineer who worked in the glory days of Kodak's empire even consider that some of us not only can, but want to do things ourselves? And this includes research, both literature and lab. It's a transparent aluminum wall of paradigm disconnect.

    No problem, and if I'm going to run down the rabbit hole with Star Trek references, I'll finish with a classic: infinite joy in infinite diversity.

    I think we can make a lot of progress understanding silver gelatin emulsions if we respect each other's goals. Some of us are interested in understanding the advanced chemistry and technology of contemporary, high-tech emulsions, with no intention of actually making one. Totally understandable. But some of us are artists and just want to make beauty. Hopefully, we can discuss emulsion making from that point of view also, with the goal of discovering the possibilities and answers, rather than dwelling on the difficulties and questions.

    d

  6. #76
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,710
    Images
    65
    Denise;

    I have said repeatedly that there are basically two types of emulsions. Simple ones that can be made in the lab and more difficult ones that might be doable in the lab with some extra skills and equipment. I ask that you please read my posts in this thread for examples and quote me rather than misquote me.

    My book and workshops taught the simpler emulsions which anyone can make. The reaction of individuals to those simple emulsions has been a spread of opinion that even simple as they are, they are difficult and others have said that they were easy. An example of a student of mine who said they were easy (and I agree) is you. You have proved to everyone that basic emulsion making is easy.

    BUT, I have added that the textbooks out there from any time earlier than about the 40s are filled with errors and/or omissions and textbooks after that era are non-existent. And, therefore, I have warned the readers. Wall in particular omits addition times and temperatures in many formulas and all of them assume active gelatins.

    The two bottom lines to this are, if I believed as you say I do in your post, why do I spend time talking people into believing how easy it is and why am I writing a book? As for your last paragraph, I do respect everyones goals and try to address them in every question asked of me. If some questions are simple, I give a simple answer and in others the answer is complex.

    Remember, the simplest emulsion making is nothing more than heat, dump and stir then coat. Its that simple!

    PE

  7. #77
    dwross's Avatar
    Join Date
    Feb 2004
    Location
    Oregon Coast
    Shooter
    Multi Format
    Posts
    785
    Quote Originally Posted by Kirk Keyes View Post
    Here's my contribution to the book club:
    "Photographic Emulsions" by E.J. Wall (1929)
    http://www.keyesphoto.com/KDKtech-E....Emulsions.html

    Again - it's old and needs to be read with a grain of salt (preferably a silver halide...).
    Thanks for posting this here, Kirk. You did a great job on reproduction. It's one of my favorite books, and actually I haven't found any bad information. I've only made about a dozen of the recipes, but none have failed. Just reading the book for the 'put your head in the time space' is valuable. It's exactly like reading your grandmother's cookbook. A certain degree of familiarity with cooking and baking techniques was assumed in those old books. How to cream an egg with sugar didn't have to be spelled out. For me, learning the 'cooking' skills of emulsion making has been a great part of the fun.

    I'll point out two short sections especially worth reading. I love the preface, pp iii-vi (pp 7-10 on your pdf notation) It was one of the very first things I read when I started making emulsions, and I return regularly to it for inspiration.

    "Practically all the knowledge is secreted in the great factories. The worker at this point stands practically in the position of the man who first discovered emulsion photography, and he must battle his way through and pull himself up until he has acquired a knowledge equal to what is known at the present day. This is far from a simple matter, but once I set to the task it proved tremendously fascinating. In order to have as few variables as possible, I purchased an enormous roll of paper and a large quantity of
    gelatine and set to work."

    Also, and relevant to the latest posts in this thread, see pages 13-14 (25-25 in the pdf) Note especially:
    "So far as the writer is aware, there is one and only one reliable test for a gelatine, and that is to make a batch of emulsion with a sample of it under the conditions followed in practice. Every gelatine maker knows, and quite possibly every emulsion maker, that" one man's meat is another man's poison."... Gelatines may be roughly divided into three classes, hard, medium, and soft, and these can be differentiated by their setting and melting points and the quantity of water they will absorb."

  8. #78
    Jerevan's Avatar
    Join Date
    Nov 2004
    Location
    Sweden
    Shooter
    35mm
    Posts
    1,812
    Images
    9
    In chapter 2 of the book in the OP, there is a description of the effort to make a "deactivated" gelatin. Compare this to chapter 1 where there is a discussion of Knopf versus Nelson gelatin. I guess no-one living today knows what exactly these consisted of, what sort of trace elements they contained. Comparing the two chapters, it seems they really are groping in the dark (as even scientists do sometimes), to describe what variable gets you where. But I may be wrong about that, I am not a chemist or even a natural scientist.
    Last edited by Jerevan; 12-12-2010 at 12:34 PM. Click to view previous post history.
    “Do your work, then step back. The only path to serenity.” - Lao Tzu

  9. #79
    Jerevan's Avatar
    Join Date
    Nov 2004
    Location
    Sweden
    Shooter
    35mm
    Posts
    1,812
    Images
    9
    I think the idea of a home-made vs the factory-made comes is comparable to the albumen papers. When it became possible to make as a manufactured item to be sold at a price - it sold in cartloads. Because then as a photographer, you weren't tied to having to crack all those eggs. But today, if you want it, you need to make it.
    “Do your work, then step back. The only path to serenity.” - Lao Tzu

  10. #80
    dwross's Avatar
    Join Date
    Feb 2004
    Location
    Oregon Coast
    Shooter
    Multi Format
    Posts
    785
    Definitely groping in the dark! You've probably heard the tales and urban legends that swirled around the subject back in the day. Great fun. That's why Wall started out his research with a huge quantity of one gelatin. That was the only way to control that vital variable. Yuh gotta love the inactive photo gelatin that Photographers Formulary sells! But, I'm starting to experiment with Knox and sheet gelatin, 'gold' and 'silver'. There's a lot of potential there. Gelatin is amazing. I've been in contact with a great guy at Eastman Gelatine Corp. He knows as much about the history of the old gelatin brands as anyone I know. There are actually quite a few modern near-equivalents. I'm working on a paper about gelatin, but you know how it goes...

    A classic read and very interesting is 'Gelatin in Photography', Vol 1, by S. E. Sheppard, 1923. Abebooks usually has a couple of copies. Here's the current page: http://www.abebooks.com/servlet/Sear...&sts=t&x=0&y=0



 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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