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  1. #21

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    Quote Originally Posted by Photo Engineer View Post
    FYI, the same is true of silver halide crystals, and back in the old days they used to judge the extent of ripening by the color of a small sample viewed on a glass slide. The color varied from yellow through green to red, but ended up being obscured when they began using varying amounts of iodide as it gave a strong yellow to red tint to most all crystals.

    PE
    Yes this is true, and everytime you wash out your equipment (in the light) one can observe colors.

    Ron, were they still doing this when you began?

    When do you think it totally ended?

    I always wondered about this, it is mentioned in both Wall and Baker I think, but (except for one ref I found later) details on how this was done in practice were vague... My hang up is I do not want to lose or fog any of my emulsion, so I could not figure out how one could differientiate between grey, blue, green, yellow and under the ortho-safelight (dark red) I use in my darklab)
    Leaving the area did not seem practical to me... do you know how it was done at Kodak?

    Did you sacrifice a coating on glass?
    and if so, to what light source?

  2. #22

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    Huh?

    Quote Originally Posted by Kirk Keyes View Post
    Ray, I now see those links do not work... try this one by Carey Lea himself:
    http://books.google.com/books?id=K5M...lver#PPA342,M1

    And another contemporary one - that mentions that Rochelle salt and hydroxide is one of many ways which to make Carey Lea's blue allotropic (collodial) silver:
    http://books.google.com/books?id=zZM...otropic+silver

    It seems to me I was making the blue form when silvering the mirrors as a side product.
    Kirk,

    Can you explain to me how this site works?
    I mean when I go there, I have never been able to get any real value out of it... perhaps there is a difference in the way we are interfacing the material...

    Are you able to see whole pages? The entire article?

    I am using a Japanese (there doesn't seem to be a choice) google interface that makes it extreamly lame!

    Are we seeing the same thing?
    I can't imagine you would even post this link if this is all you are seeing.

    Ray

  3. #23
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    Ray;

    Some workers claimed that they could judge under safelight, and others claimed that they could only see it when a few drops were sacrificed on a glass slide and brought into the light. At the time I joined Kodak, they had ceased using this method about 30+ years earlier when the controlled digests and dual runs went into effect.

    Also, for the pages Kirk gives, there is not much to see there, as he talks of the methods in general terms for the most part. I would not try to make a photograde colloid using his instructions, such as they are. They are mainly guidelines.

    PE

  4. #24

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    Quote Originally Posted by Photo Engineer View Post
    Ray;

    Some workers claimed that they could judge under safelight, and others claimed that they could only see it when a few drops were sacrificed on a glass slide and brought into the light. At the time I joined Kodak, they had ceased using this method about 30+ years earlier when the controlled digests and dual runs went into effect.

    Also, for the pages Kirk gives, there is not much to see there, as he talks of the methods in general terms for the most part. I would not try to make a photograde colloid using his instructions, such as they are. They are mainly guidelines.

    PE
    I see.

    Thanks Ron.

  5. #25
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    Quote Originally Posted by Ray Rogers View Post
    I am deeply interested, but do not really have the mathematical skills to comprehend it very well!
    One of the tough things about the subject is that theoretical descriptions are full of assumptions and simplifications, just to make the problem tractable. On the other hand, it leaves plenty of room for experimental discoveries. :-)


    Quote Originally Posted by Ray Rogers View Post
    Actually, there HAVE been several related photographic procedures that seem to use this principal.

    I have a small file on this method of color photography as I am planning some experiments in that area... I don't think I was aware of the Science article...

    .........

    What is your interest in this subject?
    (if you do not mind my asking)
    My interest is partly professional: I work in a physics department looking at the links between the electronic properties of nanostructures and their physical properties, particularly friction. The electronic structure is what determines the optical response in the visible region and there are a whole raft of reasons why I have been trying to at least keep up with the literature. Mostly I want to use simple optical microscopy to characterise a dispersion of different nanoparticles, rather than having to resort to more complex and finicky electron or probe microscopes; but also because the optoelectronics are an essential part of any applications of my work, and so much of the froth around funding and status in science departments these days revolves around patents and commercial spinoffs.

    Also, I think the subject's cool :-)

    Also, I would like to do ULF colour, and I can't see myself ever affording my favourite colour emulsions in 12x15 or 15x15 size.

    All the photographic work I have seen has been with AgCl emulsions. There was a lot of excitement in the early days of spectral recording onto AgCl on bare paper when people often observed colours, which in some cases seemed in direct correspondence with the colour of the light from the relevant part of the spectrum.

    Bensley's method is a sort of bichromic one that builds on this. He resensitized a positive print made from the orange-red part of the spectrum and re-exposed in register with a negative made with the green-blue part of the spectrum before finally giving a slow, physical development. The existing grains of the positive image provide a template for the growth of AgCl crystals in the resensitisation step, and simultaneously mask the exposure, so they influence the size, shape and position of the silver grains formed in the final step.

    It's not mentioned by the references I gave earlier, but once the nanoparticles get within a few diameters of each other their optical fields interact and you get a combination of a colour shift and a much stronger scattering. I'm intrigued by the idea that Bensley has made an all-silver image display colours not so much by tuning the size or shape of the silver grains, but by varying the spacing of the silver grains resulting from the second development. I suspect things are more dull, and he has produced a sort of Retinax pseudo-colour by mixing red and green monochrome images, but it's intriguing enough that I have started to assemble filters and film for some initial tests. The work gets shunted onto the back burner all too often though, so I'd love to hear of anything anyone else tries.

  6. #26
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    Struan;

    Many years ago, an early photographer made a color photo by placing a silver halide glass plate in contact with a pool of mercury which then set up diffraction rings in the coating. By proper illumination, the developed image was able to reproduce the original colors. I am not sure I remember who did it, my memory is faulty on this one, but they reportedly have one at George Eastman House but cannot diiplay or recreate it due to the use of an open pool of mercury. However, I think it should be possible to do by other means.

    PE

  7. #27

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    Quote Originally Posted by Photo Engineer View Post
    Struan;

    Many years ago, an early photographer made a color photo by placing a silver halide glass plate in contact with a pool of mercury which then set up diffraction rings in the coating. By proper illumination, the developed image was able to reproduce the original colors. I am not sure I remember who did it, my memory is faulty on this one, but they reportedly have one at George Eastman House but cannot diiplay or recreate it due to the use of an open pool of mercury. However, I think it should be possible to do by other means.

    PE
    Hummm....

    Ron,

    Are you thinking of Gabriel Lippmann?
    The Nobel Prize winning color photographer/physicist?

    Gabriel Jonas Lippmann (August 16, 1845 – July 13, 1921)
    (according to wiki... which also has a (poor?) example of it!)

    I have seen several good examples of his process!

    It produces the colors by interferance

    (which to me is only vaguely understandable as something similar to a visual doppler effect... uh huh, uh, well anyway)

    It can produce strikingly vivid and accurate colors.

    It has some followers and wannabes (like myself), but there are servere difficulties with the procedure which keep it from being given the true respect it deserves.

    I do believe it's day will come again!

    BTW, the images can be viewed rather easily,
    and can be also made without the Hg.

    There used to be special camera backs sold commercially just for this sort of emulsion.

    Ron, is it possible you had something else in mind?

    Ray
    Last edited by Ray Rogers; 08-29-2008 at 09:55 PM. Click to view previous post history.

  8. #28
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    Interference is the correct word Ray. I was having another senior moment. This is what I had in mind, but GEH has some and they do not show them as they cannot use mercury. So, if you can suggest another method, this will do much of what Struan has posted.

    PE

  9. #29

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    Quote Originally Posted by Struan Gray View Post
    One of the tough things about the subject is that theoretical descriptions are full of assumptions and simplifications, just to make the problem tractable. On the other hand, it leaves plenty of room for experimental discoveries. :-)

    ...it's intriguing enough that I have started to assemble filters and film for some initial tests. The work gets shunted onto the back burner all too often though, so I'd love to hear of anything anyone else tries.
    Struan;

    Yes.

    It is very interesting!

    Things behave sort of strange when very small!*

    I think I will pull out my notes from what I read last year and see if you can make any sense out of them for me!

    While different from what you described, let me just mention that if anyone reading this happens to know what happened to, or the whereabouts of a Joseph Boudreau, I would still like to contact him.

    Joseph Boudreau had doing some work with Color Daguerrotypes the last I heard, but it seems he moved or something.....

    Ray

    *
    Did they bend Laser Light?:

    Have you seen or read about how laser light can be bent as it travells through a special (< 1nm) nanotech plastic? I just caught a glimse, but it looked like they digitized the analog curve so that laser light can be made to appear to bend.

  10. #30

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    Quote Originally Posted by Photo Engineer View Post
    Interference is the correct word Ray. I was having another senior moment. This is what I had in mind, but GEH has some and they do not show them as they cannot use mercury. So, if you can suggest another method, this will do much of what Struan has posted.

    PE
    Considering Struan's field, I would imagine he is aware of Lippmann's work, but perhaps not.

    Martin, who also posts here occassionaly, can fill us in on more about Lippmann Photography, including the current status of a list devoted to it.

    Ron - Don't worry about that little 'moment'... I was about to scream EUREKA! when, while reading Herschel's hand written notes, it became obvious that Herschel had observed and described the beautiful and amazing vivid colors that could be produced by interferance... He wrote:

    " For a remarkable production of color by diffraction see [...]
    This is an most singular phenonomon "

    I was thinking he had beaten Lippmann by decades... that was untill I said to myself: "NO! No way people could have missed such an important thing!" It took a few minutes but eventually I saw "diffraction" where once that "interference" had been so crystal clear!

    Hummm...

    OK, well now I am confused myself... again!

    Two works:

    Improvements in the Diffraction Process of Color Photography
    Herbert E. Ives
    (1906)
    -----------------------------------------
    Three-color Interference Pictures
    Herbert E. Ives
    (1907)

    I think Martin could straighten this out...

    Perhaps you are not as old as you think!

    Ray
    Last edited by Ray Rogers; 08-30-2008 at 12:41 AM. Click to view previous post history.

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