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  1. #21
    AgX
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    Kino,

    I better not answer on this... The history of still colour material is already intricate. But the path of colour cinematography is much more likely to get oneself lost and I don't feel at ease on this path... Too much processes.

  2. #22
    Struan Gray's Avatar
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    Quote Originally Posted by mhv View Post
    If you read the Ctein article I linked to, you'll realize that Maxwell's color photo is actually an accident, because panchromatic sensitization did not exist yet.
    If you read my comments to that article, and the papers I refer to there, it's pretty clear that 'accident' is a misnomer.

  3. #23
    htmlguru4242's Avatar
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    Quote Originally Posted by AgX
    Why not try the Agfa approach? With modern equipment this could be a project worthwhile.
    You mention the AGFA approach. I realize that they made an early AGFAcolor film, but I have no idea how it worked.

    Could you explain in a little more detail?

  4. #24
    Michel Hardy-Vallée's Avatar
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    Quote Originally Posted by Struan Gray View Post
    If you read my comments to that article, and the papers I refer to there, it's pretty clear that 'accident' is a misnomer.
    Indeed, if some aspects of the purpose of the experiment are left unspecified, it's hard to call it an accident or a success.
    Using film since before it was hip.


    "One of the most singular characters of the hyposulphites, is the property their solutions possess of dissolving muriate of silver and retaining it in considerable quantity in permanent solution" — Sir John Frederick William Herschel, "On the Hyposulphurous Acid and its Compounds." The Edinburgh Philosophical Journal, Vol. 1 (8 Jan. 1819): 8-29. p. 11

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  5. #25
    AgX
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    the Agfa approach

    The `Agfa Farbenplatte´, later called Agfacolor as other Agfa materials too (search for my post on the Agfacolor name), employed the same principle as the Autochrome: a random additive filter mosaic.
    The difference lies in the kind of grains and that a blackout grid was made obsolete.


    The grains were made out of coloured resin. Without my library at hand I rather not state anything on the actual manufacture out of memory. One way of producing grains would be to make a true emulsion out of that resin and a non-solvent. The resin itself would have been given before the apt viscosity by using a solvent. With modern technology (mechanically, ultrasound) yielding droplets of the desired size should not be a problem.

    Coating would that emulsuion would be the greater problem. One has to achieve a tight one-droplet layer and get rid of that second part of the emulsion…
    (Though, don’t forget that in the Autochrome film also a tight one-starchgrain layer has to be established.)

    Whereas in the Autochrome film the spacing between the (irregular?) grains hat to be filled with soot, in the Farbenplatte those resin droplets layed tightly on the panchromatic basefilm, were flattened by sending the raw film through a roller system, after which the circumferences of those droplets where totally in contact.

    Writing this I realize that this would have evoked problems when processing. Coating the sensitve layer onto the mosaic would have yielded an outcome.

    I’m sorry that I was quite hasty with my advice on employing the Agfa technique. But at the same time this is the benefit of Apug, constantly proofing that one is less informed than one thought to be… In case I’d be able to deliver more information, especially on coating I shall do it.

  6. #26
    ZorkiKat's Avatar
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    Quote Originally Posted by htmlguru4242 View Post
    You mention the AGFA approach. I realize that they made an early AGFAcolor film, but I have no idea how it worked.

    Could you explain in a little more detail?
    The additive 1932 Agfacolor plate used coagulated dyes instead of starch in the mosaic filter grid. Worked in the same principle as the Lumieres' Autochrome in terms of separating, recording, and reproduction of the hues.

    The description described in Brian Coe's "History of Colour Photography" says that the filter grid starts out as a

    "mixture of three solutions of dyes in colloidal suspension. The elements in suspension were immisible but would coagulate, so that when they were coated on glass or film and allowed to dry, the dyed droplets formed into individual red, blue, and green filters. Furthermore, because the elements dried in close contact with each other, there were no interstices to be filled in with carbon black as was necessary for the Autochrome. In fact, it claimed that whereas some 92% of incident light was absorbed by the filter layer of an Autochrome plate, only 86% was absorbed by the Agfacolor mosaic."
    The less light lost from absorption made Agfacolor faster than Autochrome. The film version of additive Agfacolor was Agfacolor Ultra.

    Agfacolor-Neu was the tri-layered subtractive version which had colour couplers in the emulsion layers.

    AgX must be proposing that since the Agfacolor used different materials which no longer required the flattening and carbon filling steps in Autochrome,
    the former may be more feasible to work with.

    Another method would be forming the filter mosaic with red, blue, and green lines, like what Dufaycolor did.

    Brian Coe's book also shows a comparison (at 50X magnification) of the various filter mosaics used by the different systems. Dufaycolor's (the grid made it more consistent in terms of filter distribution) and Agfacolor Ultra's mosaics were the finest in the lot.

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  7. #27
    Mark Antony's Avatar
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    I don't know if anyone posted this guys work:
    http://www.loc.gov/exhibits/empire/gorskii.html
    Prokudin-Gorskii was a very (pre WWI) colour photographer.
    Mark
    http://www.photo-utopia.blogspot.com/

  8. #28
    Michel Hardy-Vallée's Avatar
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    Quote Originally Posted by Mark Antony View Post
    I don't know if anyone posted this guys work:
    http://www.loc.gov/exhibits/empire/gorskii.html
    Prokudin-Gorskii was a very (pre WWI) colour photographer.
    Mark
    http://www.photo-utopia.blogspot.com/
    That's the name I was looking for a few posts ago!
    Using film since before it was hip.


    "One of the most singular characters of the hyposulphites, is the property their solutions possess of dissolving muriate of silver and retaining it in considerable quantity in permanent solution" — Sir John Frederick William Herschel, "On the Hyposulphurous Acid and its Compounds." The Edinburgh Philosophical Journal, Vol. 1 (8 Jan. 1819): 8-29. p. 11

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  9. #29
    htmlguru4242's Avatar
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    Intersting about the AGFAColor mosaic. That sounds like it would be a significantly easier method to carry out, as the methods are readily available with modern technology.

    If I'm understanding correctly, it was just a suspension of 3 different color dyes which would coagulate together into a gapless filter mosaic, yes?

    I am actually aware of the methods with lines; I've read everything I can online about Dufay color (and the Joly process, which preceeded it). I also made a colored line screen on my inkjet printer, and shot a piece of 4x5 film in front of it. The color quality was horrendous, due to my printer and alignment issues with the screen, but I could definetely see it working!

    AgX, any more details on the AGFAColor methods would be wonderful!

  10. #30
    AgX
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    Actually, the reason why I proposed that Agfa technique was because it could yield the chance to produce very small grains with a very limited range of sizes. This was the reason that I used the term emulsion and not suspension. The latter would mean that one brings already sized (resin?) particles into the coating fluid.

    Concerning Coe, I faintly remember having read at some other author indeed that those resin droplets did not adhere to each other but that a flattening technique was employed.
    Anyway, Coe's description does not reveal enough to even try to reproduce that technique.

    A lot has to be found out...

    I just found on the net a hint on a comprehensive German work on the restoration of this Agfa material. But it is only to be optained the classical way, as a hardcopy from the public library.

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