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Thread: E-6 Formulas

  1. #11
    Photo Engineer's Avatar
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    Ian, the color developer and first developer are critical for correct color reproduction and image structure. I doubt if those publishing the formulas tested each and every film for RMSG and interimage.

    In fact, the films are tested against the developer, not the other way around. It is not possible for an incorrect developer formula will give proper results with all E6 films. Maybe, by optimization, one or two will work close to spec, but not all.

    E6 films are not closely related to C41 films. The C41 films use DIR and DIAR couplers to get interimage and enhance sharpness and masking couplers for color correction. The C41 couplers are designed to work best with paper (not by viewing with the eye) and are designed to work best with CD4. The E6 dyes have a spectral cut to suit the human eye and work best with CD3. The E6 emulsions are designed to work best in high solvent developers for optimum imaging and are designed to be developed to completion, whereas C41 films are not.

    There are many more differences in the sensitization levels of the emulsions, the silver quantity used, halide ratio, etc. It is a long list.

    The bottom line is that the formulas are only close approximations for E6, and will give only close approximations to specifications when used with most E6 films. The problem is that unless you do numeric or side by side comparisons, you cannot be sure of your results, only that they are 'satisfactory to you'.

    Only Kodak or Fuji-Hunt chemistry passes muster on all counts.

    PE

  2. #12

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    Quote Originally Posted by Photo Engineer
    The bottom line is that the formulas are only close approximations for E6, and will give only close approximations to specifications when used with most E6 films. The problem is that unless you do numeric or side by side comparisons, you cannot be sure of your results, only that they are 'satisfactory to you'.
    The "satisfactory to you" test is the only one that's important to a typical hobbyist, though. The elaborate tests to get everything quantitatively "correct" are important for a commercial product, but home-brew formulas are, by definition, not commercial products. Being "correct" (which I read to mean "identical to Kodak's formula") is just irrelevant for the people who'd be likely to use color chemistry formulas posted on the Internet or published in a hobbyist magazine.

    That said, your earlier comment about dye stability is cause for concern. That's something that's not easily evaluated by a photographer until it's too late.

  3. #13

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    I can't see that dye stability should be of much concern if one uses CD-3 and does not substitute one of the other color developers. The dyes produced would be identical to those produced by the official E-6 process. If one is concerned then use Kodak's stabilizer bath rather than a home brew one. What is important is the final pH of the emulsion and neutralization of any remaining leucodyes.

    I would assume that because of patent restrictions that the various films and formulas would be different. Yet Fuji film produces excellent results with the Kodak process and Kodak film in Fuji's. For example, Agfa films do not use dyes incorporated in resin beads like Kodak but rather use dyes with long side chains to prevent dye migration between color layers in the emulsion. Thus the Agfa films do not have the characteristic milky appearance that the Kodak films have before they dry. Despite different dyes the Agfa films develop correctly in E-6 chemistry.

  4. #14
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    Gerald, there is more to stability than the stabilzer in E6. It also involves silver removal and the pre-bleach chemistry as well as sulfite content in the process and pH which relates to retained developing agent.

    The dyes in all commercial films today are so-called 'kodacolor' dyes dispersed in some medium in gelatin. Agfa uses a method much like Kodak, now that the bulk of the Kodak dispersion patents have expired. The generic dye structures are cyan - phenolic, magenta - pyrazolone and yellow - acetoacetate in all films regardless of manufacturer. The specifics relate to how they are incorporated, what is in the film to enhance dye stability, and what dye hue was chosen among other factors.

    Yes, Agfa and Fuji can go through Kodak chemistry and vice versa, but I have no idea what this does to the dye stability each of these companies expects by design of their products. I have seen some pretty bad disasters, even when things go right. After all, my properly processed Ektachromes from 20 years ago look pretty bad, but some are just fine.

    I just made a post about mixing C41 chemistry. I'll reiterate part of it here adapted for E6. The developer pH values in E6 should be within about +/- 0.1 units at 20 deg C with a calibrated pH meter. Some ingredients must be controlled to within +/- 0.1 g/l or even +/- 1 mg/l to control color reproduction.

    I think hand mixing is elegant, but not worth the trouble when the potential for losing good pictures is the alternatiive, even if it is just a hobby. I spent a whole day photographing waterfalls and cliffs at a park with a friend this weekend. I would hate to see any of that hard work lost, hobby or not.

    PE

  5. #15
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    Quote Originally Posted by Photo Engineer
    1 The dyes in all commercial films today are so-called 'kodacolor' dyes dispersed in some medium in gelatin. Agfa uses a method much like Kodak,

    2 my properly processed Ektachromes from 20 years ago look pretty bad, but some are just fine.

    3 Some ingredients must be controlled to within +/- 0.1 g/l or even +/- 1 mg/l to control color reproduction.

    4 I think hand mixing is elegant, but not worth the trouble when the potential for losing good pictures is the alternatiive, even if it is just a hobby. I spent a whole day photographing waterfalls and cliffs at a park with a friend this weekend. I would hate to see any of that hard work lost, hobby or not.

    PE
    OK lets get a few facts straight:

    1 So called "Kodacolor" dyes actually are derived from Agfa innovations in Germany and their pre-war Ansco subsiduary in the US. Material (reserach papers etc) was passed to Kodak when the US Government took over Ansco in 1941, and at the end of hostilities an Allied working party published a highly detailed report into all Agfa's materials, formulae, methods of manufacture etc.

    2 None of my properly stored E3/4 or E6 transparencies have deteriorated, and they go back 30+ years. These include lab processed, home processed in either Barfen (UK Co - long gone) or Photocolor Chrome 6, and also solutions I've made up myself.

    3 + or - 0.1g is not exactly difficult and as said elsewhere a stock solution which can be diluted is better for smaller quantities.

    4 Mixing your own developers, etc is actually very easy and rewarding, and by careful methology and making up reasonable batch sizes it's extrememly easy to get good consistent results. I never dreamt of using a fresh batch of my own chemicals until I'd run a qick test.

    So to conclude would you please speak from actual first hand experience, and not from what you've gleaned from reading.

    Ian

  6. #16
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    Ian, this was all from first hand experience gained by working on the C41 process and film family.

    You have some of this backwards.

    1. So called Kodacolor couplers have no relationship to Agfa couplers. Agfa couplers were sulfonic acid derivatives similar to soaps that were dissolved in the gelatin as sodium salts, but Kodacolor couplers, invented by Hanson and Vittum were non-polar organic compounds only soluable in organic solvents. They were dispersed as droplets in gelatin. The companies that used them included Agfa, Konishiroku, Ferrania, and Fuji. When the Kodak patents expired, or through gradual licencing agreements, all companies shifted to one form of the non-polar couplers or another. Some are dispersed directly in the gelatin, others in solvents, and others are chemically attached to the gelatin through an organic reaction. There are no "Agfa" type sulfonic acid couplers used in film today. Some polymers mixed with gelatin may, in the present day, contain sulfonic acids in the backbone of the polymer. This is not related to the Agfa work.

    2. Some of my older, properly processed and stored E3 and E4 transparencies are fading. If you read discussions on the internet you will see that others say the same about many early Ektachromes.

    3. I agree, but I was pointing out more that the formula was not accurate in the first place.

    4. If the formulas are correct, I agree. Using HQ instead of HQ-SO3Na can cause problems. It is subtle, but the films were not designed for the higher activity of the HQ itself.

    Again, I speak with practical research experience, not reading books or hypothesis. I've actually mixed these solutions myself believe it or not using the actual Kodak formulas. I have really run variations on some of the ingredients to investigate the effects of developer exhaustion, sulfite exhaustion, hydroxylamine exaustion, and alkali exhaustion. To do this, I had to run concentration series of each and observe their effects on the films involved.

    PE

  7. #17

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    Again my interest in starting this thread was not to mix as a hobby (although I love to do that), but to have the formula available to me when and if E-6 kits become unavailable. I can freeze film, but I'm not sure of the shelf life of the chem kits.
    The soul never thinks without an image.
    - Aristotle

  8. #18
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    Magic, if the film is still produced, the kit will be produced. Kits will be produced until the end of expiration of the last roll produced. Film production will continue for quite some time.

    You have no worries for quite a few years, I'm sure. Someone will still be making color film and color kits. There is no need for panic. (I'm sure you are not, but I wanted to reassure you anyhow)

    PE

  9. #19

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    Quote Originally Posted by Photo Engineer
    Magic, if the film is still produced, the kit will be produced. Kits will be produced until the end of expiration of the last roll produced. Film production will continue for quite some time.

    You have no worries for quite a few years, I'm sure. Someone will still be making color film and color kits. There is no need for panic. (I'm sure you are not, but I wanted to reassure you anyhow)

    PE

    Still won't mind having the formulas, especially since I bought a Wing-Lynch processor tonight.

    Now I have to plan a trip to LV to pick it up. I'll probably have my Brother-in-law pick it up and store it till I can make a Seattle-LV trip.

    Hummm. Zion's....... Now this sounds even better now that I think of it.

    Steve
    The soul never thinks without an image.
    - Aristotle

  10. #20

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    Have no fear about Velvia 50 being phased out - RVP 100 rocks - almost identical palette, an extra stop of speed, finer grain, less "pepper" in scans and MUCH better reciprocity. RVP100 is simply much improved RVP. I have been shooting it in 120 for about 18 months (my wife picked up a stash in Japan). Unlike Kodak, Fuji seem to have a better idea about changing a good thing...

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