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  1. #21
    markbarendt's Avatar
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    Juan,

    Sure when the -1, N, N+1 and N+2 frames are printed all at once on one piece of paper they will obviously look different, so what? That's just a brightness issue.

    If you adjust to print each 6x6 frame on that roll separately with "individually appropriate" enlarger exposures designed to place the main subject at the same brightness level on the paper each time, the color balance/temperature will be quite stable between all the prints.

    Careful camera exposure is a good thing that can make printing more standardized and easier but it does not magically fix or change the color balance.
    Mark Barendt, Beaverton, OR

    "We do not see things the way they are. We see things the way we are." Ana´s Nin

  2. #22

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    Others have probably mentioned this already, but exposure certainly affects color. It affects color because it affects tonality, and with color film, color comes from tonality. In a color negative film, there are multiple layers of what is basically black and white film that you develop. The color simply rides piggyback on those black and white layers until the silver is removed in the process, leaving only the color.

    So, color film has curves just like b/w film, and exposure affects where certain parts of the picture land on this curve. However, it has three curves (or more in a four color layer film), and they don't exactly line up with each other. If anything lands off of the curve (i.e. to the left - underexposure) on any one of the layers, having full control of color balance becomes impossible. Landing to the left of your curve with a color film would be like a painter running low on one of the primaries. Your palette and your control are reduced. Thus, if you shoot in anything very far away from the color temperature the film was designed for, one or more of the color layers can be underexposed, and you should overexpose the film to help with color balancing later.

    When shooting 800 color neg film in tungsten illumination, I try to give an extra stop of exposure when I can. It is often difficult, however, as the situations in which I use this film, and in which I shoot in tungsten illumination are generally dark. The loss of a stop hurts or is simply impossible to achieve in these situations. This being said, however, IME Fuji films with the fourth color layer are incredible for low and mixed light. They color balance very nicely even when underexposed.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

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  3. #23

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    Quote Originally Posted by markbarendt View Post
    Juan,

    1. Sure when the -1, N, N+1 and N+2 frames are printed all at once on one piece of paper they will obviously look different, so what? That's just a brightness issue.

    2. If you adjust to print each 6x6 frame on that roll separately with "individually appropriate" enlarger exposures designed to place the main subject at the same brightness level on the paper each time, the color balance/temperature will be quite stable between all the prints.

    3. Careful camera exposure is a good thing that can make printing more standardized and easier but it does not magically fix or change the color balance.
    Hi Mark,

    1. No. It's not about brightness. It's about color: it's about the limits a light sensitive color media has when representing a real color and its real transitions to that same color when it reaches its own shadows and highlights... That color representation on film requires a precise amount of light: a bit less light or a bit more light produce, ON NEGATIVE, different color shifts. Forget the next steps: wet printing or scanning. Those are not discussed here... Use them as you prefer... This thread's about what happens to film. And if you don't have information on this subject, or believe the amount of light has no incidence in color or color temperature visible on neutral tones, you have the right to that opinion, but you're adding nothing to this thread.

    2. No. Not even filtering differently we get identical results. They can be close if the used exposure values were close, but with -1 and +2 (those values the masses believe valid and "the same" for color negative) you can't get identical prints... You can try to get a similar color in a subject, but other colors of the spectrum will be different. That's usual when you filter for similar skin tone in frames shot in autoexposure (exposed differently): you can get similar skins after filtering every frame differently, but other colors will be evidently different, and sometimes even the whole natural sunny mood can be lost after trying to correct with filtering what wasn't properly done with precise exposure and filtering when shooting.

    3. Wrong. Magic in your imagination only: to me this is predictable and stable 100%, a science... This is just optics and chemistry... As C-41 is a standard, indeed it's careful exposure and filtering on camera PRECISELY what produces the best color once and again.

    Cheers,

    Juan

  4. #24

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    Quote Originally Posted by 2F/2F View Post
    Others have probably mentioned this already, but exposure certainly affects color. It affects color because it affects tonality, and with color film, color comes from tonality. In a color negative film, there are multiple layers of what is basically black and white film that you develop. The color simply rides piggyback on those black and white layers until the silver is removed in the process, leaving only the color.

    So, color film has curves just like b/w film, and exposure affects where certain parts of the picture land on this curve. However, it has three curves (or more in a four color layer film), and they don't exactly line up with each other. If anything lands off of the curve (i.e. to the left - underexposure) on any one of the layers, having full control of color balance becomes impossible. Landing to the left of your curve with a color film would be like a painter running low on one of the primaries. Your palette and your control are reduced. Thus, if you shoot in anything very far away from the color temperature the film was designed for, one or more of the color layers can be underexposed, and you should overexpose the film to help with color balancing later.

    When shooting 800 color neg film in tungsten illumination, I try to give an extra stop of exposure when I can. It is often difficult, however, as the situations in which I use this film, and in which I shoot in tungsten illumination are generally dark. The loss of a stop hurts or is simply impossible to achieve in these situations. This being said, however, IME Fuji films with the fourth color layer are incredible for low and mixed light. They color balance very nicely even when underexposed.
    Good points!

    Cheers,

    Juan

  5. #25
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    I love the Portra films, but mostly use the NC varieties because I use them for wedding and portrait work where they really shine. The VC films have much more punch to them, but I find the skintones to not be as controlled. But when it comes to getting maximum color with beautiful skintones, the VC films are not to be beat.

    Exposing the films is a little bit of an art, though. To keep this on-topic, I do both optical printing as well as digitizing--but mostly digitizing for combining the images in with digital-capture images, mixing and matching them and outputting the final files to the commercial lab for printing via the chemical process. The optical print versions really don't offer much that the digital process doesn't. A couple of years ago the Portra films were changed to better handle the scanning process. This had a minimal effect on the optical printing ability, but it did change things a little bit. But the new base is much better for scanning. In a calibrated environment, it doesn't matter if it is scanned (apples) or optically printed (oranges) because the end result is going to be similar--except in the extremes of the shadows and highlights. Kodak, however, has done an amazing job of getting the film to work in either environment exceptionally well.

    Exposure of Portra films depends a lot on your lighting. For example, if you are using flash/strobe lighting, I highly recommend shooting the film at exactly the rated film speed. This is important with the VC films because the highlights will block up easily. Same thing when shooting outdoors in sunlight--shoot it at the rated film speed. But where you will want to adjust your exposure is when shooting under incandescent lighting which causes the blue-sensitivity layer to effectively underexpose by at least one, sometimes two stops. Adjusting your exposure by a full stop will usually give yourself enough density to keep the blue layer from getting noisy and losing dynamic range once color corrected.

    This is NOT a Hybrid-Photography topic, this is a discussion appropriate to this forum. It isn't about the post-process, but the exposure of the film and the characteristic curves of it that make it a valid discussion point.

    Ken Norton
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  6. #26
    RPC
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    Quote Originally Posted by 2F/2F View Post
    However, it has three curves (or more in a four color layer film), and they don't exactly line up with each other.
    The curves line up well if the film has been properly processed. This is evident in the fact that film is capable of reproducing a gray scale, indicating tracking of the red, green and blue curves along the linear portion of the characteristic curves.

    * * * * *

    A gray scale represents changes in exposure. Therefore it seems to me that there should be no significant shift in color a stop or two away from normal exposure in scenes where most everything falls on the linear portion of the curves, but a significant change could take place in the overall look of a scene with a lot of highlights or shadows (off the linear portion of the curves), where exposure changes would be aggravated, or scenes with improper color temperature for the film, as has been mentioned. Just how much color information there is in the highlights and shadows would also be a factor, I'm thinking. Therefore how much change there is, is dependent on the nature of the image itself. Not all scenes will respond exactly the same to changes in exposure.

    Significant changes taking place could be also due to improper processing which would cause crossover and non-tracking curves. Therefore the process quality should be evaluated if it has not already been checked.

  7. #27
    RPC
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    Quote Originally Posted by Tim Gray View Post
    When I look at the Portra characteristic curves, I do see the green curve having a noticeably different slope than the others.
    Keep in mind that these curves can change with processing. These are Kodak's results; different labs and home processing can give quite different results. I process at home and my curves do not look quite like Kodak's but are reasonably parallel and give a good gray scale when printed.

  8. #28

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    I have noticed that while I have mixed results with Portra films, but 160NC has been rock steady for me. That said I had no problems with 220 format 400VC until the last roll I shot I had a few frames in the middle of the roll and with the same lighting as most of the roll I could see a slight blue cast. Maybe a cloud was overhead right then, or there was a blue car behind me, or I was shooting from the shade into the sunlight. I probably would have never noticed that the "problem" if it wasn't for the fact that my roll of film was a mixed bag of shots with flash photos and daylight shots at all kinds of angles to the sun. I was just enjoying shooting so I wasn't paying a lot of attention or taking notes but of the three photos with the blue cast I recall one was taken from shade of people in sun and in front of a open garage (box of shade) so I assume that this was more a problem of my failing to meter the shot correctly than the film.

    All that said, I have to say that for me at least any problems that I have with Portra and color shift have to do with the device right behind the camera that is looking through the viewfinder.

  9. #29

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    Quote Originally Posted by RPC View Post
    The curves line up well if the film has been properly processed.
    Take a look at the manufacturer's data for any color neg film, and you will see that the curves do not exactly overlap each other even with perfect factory processing. Thus, in cases of underexposure, not all colors are underexposed equally. When underexposure occurs, some layers are always underexposed more than some others. Because of this, color balance becomes "wonky" in the least-exposed areas.

    In the same vein, if you shoot in extremes of color temperature away from that for which the film was designed, a severe exposure mismatch between color layers occurs, because even if certain layers have received enough exposure for everything in the picture to land on the curve, others may not have. For instance, when shooting daylight film under tungsten illumination, the blue-sensitive layer ends up receiving a good deal less exposure than the other two, and you see this most in the darkest areas of the print.

    So, to achieve the best color balancing ability, one must give enough exposure to the layer that will be the least sensitive in the given color temperature. I don't know how to do this exactly, but since color neg film allows so much slop, I usually add a stop and don't worry about it.

    FWIW, the same thing happens with black and white film, except that in this case, there is one layer of emulsion that responds to the entire range to which it is sensitized. Whenever possible, I give a b/w film extra exposure when shooting in color temperatures far away from the area of 5,000 K.
    Last edited by 2F/2F; 08-08-2010 at 05:31 AM. Click to view previous post history.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)

  10. #30
    markbarendt's Avatar
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    Quote Originally Posted by Juan Valdenebro View Post
    Hi Mark,

    1. No. It's not about brightness. It's about color: it's about the limits a light sensitive color media has when representing a real color and its real transitions to that same color when it reaches its own shadows and highlights... That color representation on film requires a precise amount of light: a bit less light or a bit more light produce, ON NEGATIVE, different color shifts.
    Real you say. Real is subjective in color photography. I know people who call Velvia's colors real, others that call Astia's real, others that call Reala the bomb, and people shooters that say Portra is the absolute best.

    All these films provide different palettes of color, none of them are "real".

    I do agree that when you are shooting for a very specific result, from a specific film, that will be processed a specific way, and printed on a specific paper; accurate exposure is very helpful.

    The result may be what you call real, it is what I call placement and interpretation.

    Quote Originally Posted by Juan Valdenebro View Post
    Forget the next steps: wet printing or scanning. Those are not discussed here... Use them as you prefer... This thread's about what happens to film. And if you don't have information on this subject, or believe the amount of light has no incidence in color or color temperature visible on neutral tones, you have the right to that opinion, but you're adding nothing to this thread.
    Jaun,

    Unless you are going to display the negative as the the final product, "forgetting the next steps" is silly, in fact it borders on ridiculous.

    In fact you allude to that problem in this last paragraph when you talk about the "color temperature visible on neutral tones".

    To make a positive image from a Portra negative we have to shine light through it, correct it's balance, not just for the scene (which is arbitrary) but for the orange base (which is affected by processing, age, heat, film batch), and invert it to some media where the paper adds a color bias too.

    Papers have their own curves with shoulders and toes that affect how much of a the film's curve will be visible and the color balance. In a straight print (especially from a thick negative) much of the info on a negative falls outside the paper's range. Burning and dodging can bring much of that info into the papers range, but that process is arbitrary.

    These requirements are variables, their application is arbitrary, not fixed by law or the limits in physics and the "color balance" isn't "visible" without applying the variables.

    Making a positive is a required part of the process; if you want to see color balance in real life, you can't ignore the process of making the positive.

    Quote Originally Posted by Juan Valdenebro View Post
    2. No. Not even filtering differently we get identical results.
    I'm not saying that the photos will be exactly the same, I'm saying that the color balance doesn't move much and essentially equal colors are available in the print. The result is fully and absolutely dependent upon the printing process.

    How we use the enlarger to place exposure on the paper to create our photo and how much we burn and dodge, is purely arbitrary, just as our color preferences are.

    Reality is not what we get on paper, we get an interpretation.

    Quote Originally Posted by Juan Valdenebro View Post
    3. Wrong. Magic in your imagination only: to me this is predictable and stable 100%, a science... This is just optics and chemistry... As C-41 is a standard, indeed it's careful exposure and filtering on camera PRECISELY what produces the best color once and again.

    Cheers,

    Juan
    Sure C-41 (and RA-4) has a commercial standard; some labs are very good at that, some aren't. A perfect standard in practice it is not. Lab complaints here on APUG are ample proof of this.

    Not only that, just as for B&W film, the process can be adjusted, with time and or temp, to suit the choices of the photographer's vision. With practice Push/Pull, Expand/Contract are very workable and used regularly with C-41.
    Mark Barendt, Beaverton, OR

    "We do not see things the way they are. We see things the way we are." Ana´s Nin

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