400PortraNC and blue skies

Discussion in 'Color: Film, Paper, and Chemistry' started by Bruce Watson, Sep 20, 2007.

  1. Bruce Watson

    Bruce Watson Member

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    I've got a sheet of 5x4 Portra NC that's giving me a little trouble. Nothing I can't handle, but I'm curious if this is normal for this film and if it is, what is normally done to correct it at exposure time.

    The image is a late fall / early winter scene of fall color with snow and some blue sky showing through the clouds. When I balance everything to get the snow and clouds white, everything else falls in line with the single exception of the blue sky. That is, the whites are white, the grays are gray, the greens and yellows and reds are all fine. The sky blue becomes cyan however, which is somewhat disturbing. No filters used during the exposure.

    Is this normal for this film? I don't have a lot of experience with it because it's so expensive. I will say that it's tack sharp and hardly any more grainy than 160PortraVC. But why the oddball color balance problem?
     
  2. Photo Engineer

    Photo Engineer Subscriber

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    What paper are you printing on?

    PE
     
  3. Bruce Watson

    Bruce Watson Member

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    I knew someone would ask. I didn't want to say because it's bound to make someone here mad, but here goes. I'm drum scanning the film. But in my defense I *am* using film!

    But this raises a good point. I can hop down to the prolab that developed the film and have them make an 10x8 for me - they still do color enlarger prints. That'll tell me whether it's the film or the scan... maybe.
     
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  4. Photo Engineer

    Photo Engineer Subscriber

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    Bruce;

    We used to use the KS Paul drum scanner at EK for scans to compute the matrix for correction in the film. There is no shame in that. The film should not have that level of crossover, so it may be the scan.

    I know that Fuji paper sometimes prints Kodak films less well than Kodak paper prints Kodak or Fuji film. This is due to the sensitivities of the 3 layers in the Kodak paper.

    PE
     
  5. Bruce Watson

    Bruce Watson Member

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    I'm not ruling the scanner out yet. But I'm confused as to what would cause a color change in just the sky. It's not an overall color cast which is what I'd expect if the scanner's blue channel, for example, was out of calibration. If that was the case, I'd expect to see a similar shift in greens toward yellow-green maybe. But the evergreen trees in the photograph remain a blue-green like they are supposed to be. Which is why I'm asking about the film.

    But in truth I don't have any clear idea how to induce this kind of thing. I don't see how the film could do it. I don't see how the scanner could do it either. Which is why I'm asking questions.
     
  6. Photo Engineer

    Photo Engineer Subscriber

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    Either could do it by creating crossover, where one layer crosses over the other. Bad film, bad process or bad scan.

    PE
     
  7. copake_ham

    copake_ham Inactive

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    If you just scan the negative into a file and view it via software - do you still see a cyan sky?

    Why not upload the pic scanned from the negative here and let's see what we see?
     
  8. Bruce Watson

    Bruce Watson Member

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    I don't want to post it because in my experience with severe downsizing and converting to very small working spaces (sRGB), then converting to jpeg, blue skys are among the first things to color shift. In other words, you wouldn't likely see anything amiss in the tiny bit of information that would be left for you to see.
     
  9. Bruce Watson

    Bruce Watson Member

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    I've got a working theory on what this might be. See what y'all think.

    I'm thinking it's possibly an orange mask problem. Specifically, that the scanner software picked off the orange mask but didn't get the decompression of the yellow dye layer right in the process. I'm thinking this because this film came to market after the drum scanner maker left the market -- they couldn't have corrected for this new film completely since they didn't know it existed.

    Has a nice ring to it, but I still don't understand why it only effects the blue in the sky. The white clouds in the sky are white - no color cast. But the blue is definitely cyan. Hardly any magenta in it at all. Whereas the blue-greens of the spruces and the blue-reds of the maple leaves (there are some orange-reds too) are unaffected. I would think a mask removal problem would leave a cast over everything. How does it know to just mess with the blue parts of the sky and leave everything else alone???
     
  10. Photo Engineer

    Photo Engineer Subscriber

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    Scanning software is built to accept the orange mask and treat it accordingly. It is a color correction mask for magenta and cyan, and is 'colorless' to both color paper and to scanning software for color negative films.

    PE
     
  11. nworth

    nworth Subscriber

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    I've been using 400VC and, before that, 400UC. I noticed that the skies came out in all sorts of blue hues, from intense dark blue to washed out cyan. I was a little distressed, and I started looking for some answers. The most important one was that the sky color really does vary a lot, depending on such things as time of year, direction, time of day, altitude, wind conditions, level of smog and dust, moisture, and who knows what. It varies from dark blue to bluish-cyan - really. The high saturation color films, and probably the newer NC types as well, tend to exaggerate these differences.
     
  12. Photo Engineer

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    I've had another thought on this. It could be due to the amount of UV in the light. I always use a UV filter to minimize any alteration of colors by variations in the UV content of daylight.

    Even though the film has a UV filter, and lenses filter out some UV, there is always a small but variable amount that strikes the film.

    PE
     
  13. Bruce Watson

    Bruce Watson Member

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    Just got the optical print back from the lab. They had to fight with it as it's not at all an easy negative to print.

    The color balance on their final print is fairly close to neutral, that is, without much of a cast. And the sky in the print is a nice natural blue. So the problem is clearly the scan and not the film.

    I still don't know what I did wrong, but this is the wrong forum to discuss that. I just wanted to post a vindication for the film.
     
  14. Marco B

    Marco B Member

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    Sounds to me like a scanner color profile problem. Any new film actually needs it own profile. If the drum scanner was not calibrated for this film, and you just used a generic color negative profile, it's bound to be off.

    I had severe problems scanning Fuji RVP100 dia positives on a Flextight scanner at a professional lab using a generic dia positive profile. All colors were way off... The same profile was giving good result with Fuji Provia100F...

    Probably a stupid question, but you don't mention it, so I'll ask anyway: Your own screen is properly hardware calibrated I assume??? If not, you can never judge the result of the scan.