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  1. #31
    Bob Carnie's Avatar
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    Dave
    I find nothing unusual with your results by adding the cyan you have reached a good balance and that is all that is required.
    When printing cibachrome I am continually in the cyan filter to balance the colour. You have just came across an unusual situation that you have solved by using the third filter available to you and zeroing out one filter.
    As others have pointed out for colour negative printing one usually require only the yellow and magenta dials with the yellow number higher.

  2. #32
    Ed Sukach's Avatar
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    Interesting. I'm wondering ... are you using the proper lamp in the enlarger? And - what film, specifically, did you use?

    Just curious. Certainly there is no "law" stating "Thou shalt NOT use cyan filtration", but I think it is a trifle unusual.
    Carpe erratum!!

    Ed Sukach, FFP.

  3. #33

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    The lamp's an ELC - came with the Chromega color head. Film with the Color Checker frame is Portra VC-160, 120 size. I also shot a roll of UC-400, but haven't made a print from it yet. I did make contact sheets of both rolls, and color balance looks good on both.

    Unusual is right. I've never run into anything like this.

  4. #34
    Photo Engineer's Avatar
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    Ed, I would like to address your comment about cyan filtration.

    Since color negative paper has no blue light absorbing layer, and the yellow layer is on the bottom with cyan on top, there is a virtual requirement that filtration be on the red (m + y) axis only with no cyan. If you go to the cyan side, you are apt to get bad color contamination among other things due to crosstalk by blue light.

    This will result in greenish cyans, and reddish magentas for starters.

    So, when I see cyan filtration with negatives, I troubleshoot the entire system as something is seriously wrong and will lead to bad prints. As you say, there is no law that says this cannot happen, but when it does it seems that something is wrong and should be fixed for optimum performance.

    PE

  5. #35

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    Quote Originally Posted by Photo Engineer
    Ed, I would like to address your comment about cyan filtration.


    So, when I see cyan filtration with negatives, I troubleshoot the entire system as something is seriously wrong and will lead to bad prints. As you say, there is no law that says this cannot happen, but when it does it seems that something is wrong and should be fixed for optimum performance.

    PE
    That's why I'm not going to use Fuji paper when the box in question is gone. I'm a lot more comfortable using the 45M 80Y I need with Supra papers.

  6. #36

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    Cyan filtration is not an unusual thing for me - but I don't usually use more than C20, and only in case when I need to re-balance the whole pack (if I have to remove, say, Y20, but Y is already 0). In such case I add C20, M20, and Y0. But, honestly, my numerical data shouldn't be taken as a last instance - the numbers refer to an old Magnifax II with Janpol Color 80/5.6 lens, and an Osram Halolux 150W household opal halogen lamp. To print Fuji NPL 160 on that system (Kodak Endura Supra paper, F surface) I have to switch on the whole magenta available (M100), with no yellow filters at all. NPS requires some yellow, as well as Agfa Optima - but not too much. The colors, though, are dead on as a result of all tweaking

    Old Janpol showed itself from a good side - I didn't expect it would work at all, but the prints' sharpness and colour are quite OK with it. I didn't try to print 135 film with it, because I prefer minilab for such things

    Zhenya

  7. #37
    Ed Sukach's Avatar
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    Quote Originally Posted by Photo Engineer
    Since color negative paper has no blue light absorbing layer, and the yellow layer is on the bottom with cyan on top, there is a virtual requirement that filtration be on the red (m + y) axis only with no cyan. If you go to the cyan side, you are apt to get bad color contamination among other things due to crosstalk by blue light.
    And now to explain, in not more than 10 words...
    Not a place where I want to be.

    If one starts to "balance" the light from the Dichroic Color Head, one will occasionally "run out of room" (usually because of a great mismatch of film-to-ambient light source temperatures). As an example, to obtain balance, with a certain negative, the amount of yellow filtration will be too great, and cannot be corrected, even when the yellow fitration is reduced to zero.
    What is then necessary is the introduction of "cyan filtration" to change the starting point of the filter pack. If 20cc of cyan is introduced, the actual value of "yellow" will be increased to +20cc, and will allow further reduction (magenta will be also affected to the same intensity, +20cc more than before). That is why there is a cyan filter.

    THis is one of those things that are far easier to understand in practice, than it is to describe it in writing.

    ... Almost missed this.... There is, most certainly a "blue sensitive layer" in Color paper. An example from the data sheet for Agfa Signum:

    "Emulsion structure:

    The light-sensitive emulsion consists of silver chloride crystals imbedded in gelatine. The red-sensitive layer contains the cyan component, the green-sensitive layer the magenta component, and the blue-sensitive layer the yellow component."
    Carpe erratum!!

    Ed Sukach, FFP.

  8. #38
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    Ed, the blue sensitive (yellow dye forming layer) is different than the blue light absorbing layer present in films but not in papers. The blue sensitive layer is on top in films followed by a yellow dye layer to absorb blue light and prevent punch through of blue light into the underlying layers.

    In paper, the yellow dye layer (blue sensitive) is on the bottom therefore preventing the inclusion of a blue light absorbing layer. All layers in paper have blue sensitivity and must rely on speed differential for separation of color and prevention of color cross contamination. This requires that the blue speed of the yellow layer be much higher than red speed of the cyan layer and the use of yellow filtration to reduce the blue speed of the blue layer down to equal the red speed. At the same time, it reduces the blue speed of the red layer to effectively zero thereby eliminating crosstalk. Average blue layer grain size in papers is about 2 microns and for the red layer is about 0.2 microns, a factor of 10x reflected in their raw speeds of both to blue light.

    Moreover, adding cyan filtration using a good cyan filter, should have little effect on the yellow component (or blue light) in the beam of light. If it does, then you have a bad cyan filter with lots of crosstalk. Even with 'bad' cyan filters, a change of 10 or 20 Cyan should be only about 5 yellow or less.

    Paper structure

    C/IL/M/IL/Y/Support

    Film structure

    Y/Yellow dye IL/M/IL/C/Support

    Film speed for tungsten C<M<Y proportional to tungsten emission. This yields a neutral to the tungsten light.

    Film speed for daylight C=M=Y (approximate) to daylight 'neutral white' emission. This yields a neutral to daylight.

    Film speed for paper C<M<Y proportional to tungsten illumination + dmin of film + ~50R. This requires a piece of film and about 50R to achieve a neutral to average tungsten enlarger lamps.

    PE

  9. #39
    Ed Sukach's Avatar
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    Quote Originally Posted by Photo Engineer
    Ed, the blue sensitive (yellow dye forming layer) is different than the blue light absorbing layer present in films but not in papers. The blue sensitive layer is on top in films followed by a yellow dye layer to absorb blue light and prevent punch through of blue light into the underlying layers.
    All very interesting, and I'm going to cut some slack here. Generally true, but in Film there is a yellow filter layer immediately below the blue sensitive and UV filter layers. That yellow filter is not present between the green and red sensitive layers... and introduces a Yellow BIAS that is usually sufficient to eliminate the need for cyan filtration in printing.

    Be that as it may, I commented on the statement, "Color negative paper has no blue sensitive layer" (not true) - not that the structure of color film and paper emulsions were "the same".

    Interesting - It has been some time since I've delved through my collection of Data Sheets - the first book that I came upon was Agfa. Apparently they balance all their color paper to produce a neutral grey - equal parts of red, green and blue - when exposed to the light emitted, unfiltered, from an enlarger lamp with a color temperature of ~ 3000K. An enlarger with a lamp emitting a different color temperature will, necessarily require different filtration.
    Carpe erratum!!

    Ed Sukach, FFP.

  10. #40
    Photo Engineer's Avatar
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    Ed, sorry but I never said what is reflected in this quote from your last post.

    "Be that as it may, I commented on the statement, "Color negative paper has no blue sensitive layer" (not true) - not that the structure of color film and paper emulsions were "the same". "

    I actually said "Since color negative paper has no blue light absorbing layer, and the yellow layer is on the bottom with cyan on top" so there seems to be some misunderstanding here.

    Also, Agfa may do as you say here;

    "Interesting - It has been some time since I've delved through my collection of Data Sheets - the first book that I came upon was Agfa. Apparently they balance all their color paper to produce a neutral grey - equal parts of red, green and blue - when exposed to the light emitted, unfiltered, from an enlarger lamp with a color temperature of ~ 3000K. An enlarger with a lamp emitting a different color temperature will, necessarily require different filtration."

    But this merely gives an approximation without taking into effect the masking of the color negative. This is done by including an average dmin bias. In addition, this does not account for how the manufacturers balance for the average population of color negative materials they make. In fact, please take note of the fact that the current Endura papers has increased green speed (and a higher basic magenta filtration) by about 15M compared to the Supra family of papers which I found stable over 10 years. This was not done without a reason.

    In the end, this is why each color paper manufactured out there has a slightly different basic response pattern and each color negative film has a different basic balance when printed. The photofinisher must take these into account as well as the home darkroom worker. Some papers respond better across all film types than others and this is related to the speed relationships of the blue and green sensitive layers (red being taken as the zero point) and the spectral sensitivities of the papers themsleves.

    PE

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