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  1. #21
    Athiril's Avatar
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    I've tested various split bathes on C-41 and ECN-2 films.

    What I've found is that there -has- to be development (low contrast) in bath A, if only a little bit, otherwise, very thin negatives from very low EI's every time (and bad colour).

    The carry-over amount in the emulsion is simply not enough to have developing only occur in B. Even with vastly increased developer levels in bath A.


    And with this.. you can alter effects and colour by varying time in Bath A.

    Some people have left out the sulphite in Dignan's formula and found they got essentially nothing on their negs. When they finally tried it with the sulphite, it was greatly improved.

  2. #22

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    Quote Originally Posted by Athiril View Post
    I've tested various split bathes on C-41 and ECN-2 films.

    What I've found is that there -has- to be development (low contrast) in bath A, if only a little bit, otherwise, very thin negatives from very low EI's every time (and bad colour).

    The carry-over amount in the emulsion is simply not enough to have developing only occur in B. Even with vastly increased developer levels in bath A.


    And with this.. you can alter effects and colour by varying time in Bath A.

    Some people have left out the sulphite in Dignan's formula and found they got essentially nothing on their negs. When they finally tried it with the sulphite, it was greatly improved.
    Yup, pretty much my experiences dealing with B&W divided developers. I loaded up Bath A to the maximum, I think it was hydroquinone solubility, whatever, and it wasn't enought to kick ass in Bath B.

    Take that and multiply times three emulsions times all the layer interactions..............

  3. #23
    Photo Engineer's Avatar
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    Guys;

    I wish you two were here. I have an awesome tutorial on this subject I am aching to give you. It is too long to write out as it would take several hours. There is so much to learn on this subject. But, you see the basics of it.

    PE

  4. #24
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    Why is there color crossover in divided C-41?

    Quote Originally Posted by Photo Engineer View Post

    Oh well, have fun.

    PE
    in addition to all the very useful information in this thread, the above is probably the best admonition of all. I might -might- try divided c-41 at some point, just for fun. Obviously it won't be a go to solution for critical work!

    Once I am back in the USA this summer, with more ready access to raw chems, I'll probably give it a go. In the mean time, I'm satisfied with spending my spare time improving my home brew water bath to deliver precision temperature control on the normal process.

    Thanks for all the insight, as usual.

  5. #25
    Photo Engineer's Avatar
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    Just make sure that your database is proof against Chinese hacking!!!!!!



    PE

  6. #26
    Athiril's Avatar
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    One other thing with divided colour developers I've noticed when playing around to see what controls I had over the image:

    I used a very minimal amount of KOH for Bath B instead of the several decagrams of carbonate the usual recipes specify.

    I did indeed get colour images, pH was indeed sufficient and didn't drop. The definition was terrible.. I don't even mean sharpness. There was like no gradation of colour across objects.

    Rather than just pH - the amount of base used needs to be sufficient as well it appears. Though someone said hydroxide bases are not good for colour?

  7. #27
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    Dan;

    Try Tri Sodium Phosphate at high concentration as bath B. That might work better. But, It will not come close to the real color developer.

    PE

  8. #28
    Athiril's Avatar
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    Okay I finally went to play around with another split bath out of curiousity.

    Image (quick colour balance), the sharpness and grain are pretty good for this film (made in Japan Agfa Vista 400)

    Bath A
    Pinch of Sodium Sulphite
    CD-2 – 9g/L
    Sodium Sulphite – 9.6g/L
    Sodium Bisulphite – 0.54g/L

    Measured pH 7.1

    Bath B
    Potassium Carbonate – 50g/L
    Potassium Iodide – 1.4mg/L
    Sodium Thiocyanate – 220mg/L (I’m sure my thiocyanate needs drying out too btw).



    Detail crop


    Out of focus grain crop

  9. #29
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    Unfortunately, we have no real color patches or other colors for comparison and so we do not have a clear idea of there being any errors in rendition of color.

    Sorry Dan. Put a color chart and/or flesh tones and greens in the photo.

    PE

  10. #30
    Athiril's Avatar
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    Ron;

    That was beyond the scope of this test. This is the first try with the first roll, I haven't settled on a specific formulation. For those kind of tests with a gretag macbeth 24 colour patch (Will be using the X-Rite Passport), I will be using CD-4.

    Anyway, here is an outdoor shot, colour balanced, but not profiled (profiling with a colour patch would remove crossover).

    Last edited by Athiril; 02-21-2013 at 06:52 PM. Click to view previous post history.

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