"Cross-Processing", but not really... alternative processing techniques for E6 & C41

Photo Engineer said:

Yes. But without Pan Matrix, you cannot go further with Dye Transfer. You need another process.

The filters used normalize the differences in the dyes and spectral sensitivities.

PE

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Shouldn't I be able to duplicate those filters, or make changes to accomodate another pan film's different response, using a diachronic source?

Yes, you can, but what can you do to make a print is another matter.

The filters are WR98, 99, and 70 and the exposures and contrast are adjusted to give a neutral in the process you are using.

PE

Michael, I know exactly what you mean. I wondered the same thing for a long time, whether the orange mask would make separations difficult. But along with what Ron is saying, it's not a problem.. something I was quite surprised by!

I actually have in front of me a copy of Wall & Jordan's 'Photographic Facts & Formulas' from the library, and it explains this very well.

Basically, the orange mask is a product of two separate masks. In the two layers that require masking (cyan & magenta), the couplers are made to be colored themselves. Upon processing, the colored-couplers are destroyed where the image density is, and left to remain where there is none. Thus, the coloring matter is inversely related to the dye image.

Cyan has unwanted blue & green absorption, so the coupler in this layer is reddish and acts to mask these unwanted absorptions. The magenta layer has unwanted blue density, and the mask here is made to be yellow.

Interestingly, as is the case in all printing schemes as far as I know, yellow is good enough to not require masking. Damn that yellow...

Now if that wasn't enough, the dye-transfer printing matrices must also be masked to account for unwanted absorptions in these dyes. So first you have to get good clean information from your separations, and then you have to "unmuddy" the waters again during printing.

Ok, it sounds like despite the fact that we have a significant hurdle in finding the "proper" filter settings using a fair amount of empirical testing, in theory there is no reason we couldn't eventually work out the details to shoot C41 and print separations optically.

Mountainous, but possible.

The Kodak Dye Transfer book (reproduced here somewhere in a PDF) and Jim Browning's web site explain all of this in detail.

BTW, a masked color negative film has a positive mask image that contains the correction information.

PE

michaelbsc said:

Ok, it sounds like despite the fact that we have a significant hurdle in finding the "proper" filter settings using a fair amount of empirical testing, in theory there is no reason we couldn't eventually work out the details to shoot C41 and print separations optically.

Mountainous, but possible.

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I think it's not even mountainous. It's fundamentally no different than making separations from slides or still-lives, the mask having no deleterious effect other than extending exposure times. You use the appropriate filters and the only testing necessary will be exposure times, but filter factors are given.

Unless you're talking about the proper filter settings of a dichroic head, in which case I don't know enough to speak authoritatively on the matter.

PE is right; check Kodak publication E-80 I believe.

As for the filters, 70, 98, & 99, here is what my Kodak filter handbook says:

70 - Dark Red. Narrow-band monochromat used for making separation positives from color negative films. Also used for 3-color printing on color papers.

98 - Blue. Equivalent to #47B plus #2B filter. Used for making separation positives from color negative films. Also used for 3-color printing on color papers.

99 - Green. Equivalent to #61 plus #16 filter. Used for making separation positives from color negative films. Also, for 3-color printing on color papers.