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  1. #11
    hrst's Avatar
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    John,
    You can also see the datasheets that are available on Kodak website, and they show that the RGB sensitivities are very close if not the same as in the old product. That's definitely not a problem. Filter pack changes are minor.

    Go to www.kodak.com/go/professional, product information, papers. See spectral sensitivity curves.

    The sensitivities are as they are for technical reasons in paper manufacture (the layer order & lack of yellow filter layer, PE can definitely explain more), and it "happens" to compensate for orange mask, too.

  2. #12
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    Well, as I have said, if you consider red speed = 0, then green = about 0.8 log E faster and blue = about 1.2 log E faster. This balance is needed for several reasons.

    1. It makes it tungsten balanced
    2. It compensates for the mask
    3. It removes the blue sensitivity of the R/G layers from the image

    The Yellow layer is on the bottom, for reasons of dye stability and there is no yellow filter layer in the coating for this reason.

    These have not changed for over 50 years. The changes for digital printing are those I mentioned earlier regarding the ability to print with the high intensity scanning printers.

    PE

  3. #13

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    Would additive printing via RGB (say with a Minolta Beseler 45A head) be able to accommodate using "digital" RA-4 paper? It can vary the exposure on a per-color basis easily, using the additive colors. It also powers the head via electronic flash, so the short/high intensity side of things might be covered a bit too?

    Just a thought.

    -Ed

  4. #14
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    It might improve color, but IDK for sure.

    The problem is that it might increase individual exposure times and worsen the reciprocity situation. This paper needs very short high intensity exposures.

    PE

  5. #15
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    Quote Originally Posted by EdSawyer View Post
    Would additive printing via RGB (say with a Minolta Beseler 45A head) be able to accommodate using "digital" RA-4 paper? It can vary the exposure on a per-color basis easily, using the additive colors.
    What? You can vary the exposure on a per-color basis just as easily with subtractive dichroic enlarger heads. There might be a small difference in spectral response but I think you have understood something fundamentally wrong.

    My point earlier was that there might be a need to adjust CONTRAST per color. It cannot be done by modifying light. You have to make separation negatives and adjust their processing parameters to do that.

    Maybe, if the crossover is mostly in highlights and is very slight, color-filtered preflash could help.

    But, OTOH, some people say that the color crossover really is not a problem. If the overall contrast is too high, it can be handled with methods given in http://www.apug.org/forums/viewpost.php?p=1157100 .

  6. #16

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    Flibber, flubber, you're right. Dang! I'd somehow imprinted on my mind that the characteristic curves of RA-4 papers were offset like the characteristic curves of C-41 films, to complement that offset. Instead it must the "default filter pack" that cancels out the offset of the C-41 curves. My apologies for having something so wrong so firmly wedged in my mind! So you can print with the same filter packs on this paper.

    However, right on the promo page for Supra Endura VC Digital, it says "expanded color gamut". To me, that means that if you plotted the positions of the cyan, yellow, and magenta dyes on this paper, they would form a larger triangle on the CIE Chromacity Chart. Closer to the outer boundary, which is the "spectral" locus. That's what larger gamut means when you're shopping for a printing system or a monitor. (Just that the monitor triangle is red, green, and blue.) Am I interpreting this correctly? It's certainly what I would want a "wide gamut" printing system to do.

    The ink-jet vendors have been working on wider gamut for years. They are Kodak's real competition, not Fuji. So Kodak has (properly) responded with wider gamut RA-4 papers for digital printing. Good move in my opinion. (Kodak has had the wrong competition or market in mind too many times in the last 20 years.)

    Unfortunately, Kodak only gives the "spectral dye density" curves for papers. They don't give the CIE coordinates of the three dyes. That would be the way to see what the gamut of each paper it. However, looking at those curves for Supra Endura VC Digital (E-4042) and Portra Endura (E-4021), the ones for the VC paper look to more "sharp cutting", that is narrower. I suspect that indicates that the dyes in VC are closer to "spectral".

    (I'm painfully aware of the quirks of wide-gamut devices, because I use an HP LP2745w monitor, which has a gamut the same as Adobe RGB, rather than the much smaller sRGB monitor most LCD monitors support. Great when color management works, a headache for non-color-managed applications, or broken ones like Firefox 3.x, which only properly color manages images with ICC V2 profiles, but not ICC V4 profiles.)

  7. #17
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    I think you are right. Sharper-cutting dyes indeed create wider gamut (of course if the absorbance peak is at the correct wavelength). There might be a drawback; under some cheap fluorescent lights, the sharper dyes might look worse if they don't match with the peaks in the light's spectrum. I don't know if this is a real problem, just speculation. I have however seen problems under some fluorescent lights with standard Supra Endura. Prints shift in magenta-green depending on light source more than "neutral" paper or grey card appears to shift.

    Note that the final dyes and the spectral sensitization dyes do not need to have any connection with each other. So, the spectral sensitization dyes should be selected to match the RGB lasers used in digital exposure, or the C-41 film dye absorbance peaks, but luckily, I think that the lasers were matched first at the time the paper was optimized for optical printing only, so there's no need to change this anymore.

  8. #18
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    Adjust through developer chemistry?

    Quote Originally Posted by Photo Engineer View Post
    Digital papers are optimized for high intensity short exposures. They are also optimized for printing via scanning the paper with the light in lines rather than a single overall exposure. To do this, the reciprocity and some other factors had to be changed with regard to this new method of exposure.

    It is indeed a new emulsion set.

    PE
    PE:

    Just wondering here.

    Could the response of these digital papers be made more suitable for optical printing by adjusting the development chemistry?

    I envision an additive for the developer (no doubt with a difficult to locate Kodak catalogue number ) which is intended to be used only by photographers and labs who are only printing optically. The now main-stream labs that print digitally wouldn't use it, but the individual photographers and labs with older equipment could.
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  9. #19
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    Matt;

    AFAIK, there is no such thing. Sorry. Reformulation of the entire developer might help, but that would take a lot of work and may not yield anything useful.

    PE

  10. #20

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    From personal experience:
    I tried to print on "Kodak Metallic Endura" (a digital paper) a few weeks ago. These were landscapes with blue sky, green and brown grass, grey rocks and some trees. The results were absolutely un-usable. If rocks and clouds were neutral, the sky was pure cyan; when the sky was o.k., rocks and clouds were pink. The brown of the trees was awful. Parallel prints on Supra Endura ("analog" paper) were perfect (BTW, is was Ektar 100 in MF)
    In clear words: These were not minor color shifts, but the colors were really way off.
    Conclusion: "Digital" paper might be usable with genres where color fidelity in all colors is not necessary, like (mostly) monochrome sceneries, some product photos, or experimental work. But for anything with a palette of "natural" colors, they are useless.
    In my experience, many amateurs have extremly low standards when it comes to judging own prints (it's like "my child"). This might be where the positive opinions on the web are deriving from.
    For me, when "analog" papers are gone, the traditional color darkroom will be history.

    Georg

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