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  1. #1
    rfshootist's Avatar
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    Help ! Dynamic range C41

    Hi to all,

    i have decided to work a bit more careful in future and make a contrast analysis when the lightning (= contrast) gets critical l My Gossen Starlight allows me to use the Spotmeter for that purpose, it calculates the range in fstops.

    I seem to be too dumb to find a reliable source anywhere in the web which tells me something about the dynamic range of C41 film and slide film.

    I have in mind 12 stops for B&W, 6 to 7 for slide, and about ten stops for C 41 (1:1000 ?) , not sure tho if these numbers are up to date for the modern multi layer films, I blieve to remember that somebody said 12 stops for some colour films would be state of the art now ?

    Nice would be also a table, which translates the contrast ratio to fstops ?

    Many thanks in advance !

    Bertram
    A la recherche du temps perdu: www. bersac.de

  2. #2
    Helen B's Avatar
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    Hi Bertram,

    If you look on page 2 of this thread I have attempted, in my usual convoluted and obscure manner, to cover some of the questions you are asking.

    Colour negative film is more of a part of a fixed system than B&W negative film is. The manufacturer's characteristic curves will tell you the overall dynamic range of colour negative film (with no allowance for contrast reduction by lens flare), but how much of that dynamic range can be used in a single straight print depends on the printing paper. Your film might have a dynamic range of 12 stops, but the characteristic curve of the printing paper results in only seven stops, for example, appearing on a straight print. The rest of the dynamic range of the film could be considered as under- or overexposure latitude. It's advisable to avoid the use of the underexposure latitude, because most colour negative films have a marked increase in graininess at the toe. This is an issue when finding your practical film speed. There is a lot of overexposure latitude.

    If there was a paper made that could use almost the full dynamic range of colour neg film, the prints would look awfully flat for most subjects. You can, of course, make contrast masks and use other contrast reducing techniques to utilise the full dynamic range of the film.

    It's a slightly different matter if you scan (wash my mouth out with soap and water). Then you can capture everything that is on the negative, and adjust the contrast as you wish.

    If the contrast ratio is CR and the stop range is SR stops:

    CR = 2^SR

    SR = log CR/log 2

    Contrast ratio - stops

    32 - 5
    64 - 6
    128 - 7
    256 - 8
    512 - 9
    1024 - 10
    2048 - 11
    4096 - 12


    Best,
    Helen

  3. #3
    rfshootist's Avatar
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    Quote Originally Posted by Helen B
    Hi Bertram,
    Colour negative film is more of a part of a fixed system than B&W negative film is. .. Your film might have a dynamic range of 12 stops, but the characteristic curve of the printing paper results in only seven stops, for example, appearing on a straight print. The rest of the dynamic range of the film could be considered as under- or overexposure latitude.

    It's a slightly different matter if you scan (wash my mouth out with soap and water). Then you can capture everything that is on the negative, and adjust the contrast as you wish.

    Best,
    Helen
    Dear Helen

    thanks so much for takin that much time for these detailed and knowledgeable explanations ! You answered all my questions and even some I was too dumb to ask at all !!

    I knew this limitation of paper but you first made clear to me what that really means for the photog thinking about how a photo must get exposed.
    I mean how to use the film range exceeding the paper range as "latitude"!
    I never had dealt with printing colour, leaving aside some friends experiments with Cibachrome in the 70s, which I observed with astonishment and admiration. All forgotten.

    Thanks for the contrast table too, that was what I needed !
    The limited dynamic range of film, compared to the photogs eyes, is for me one of the most interesting issues in photography, much more interesting than the the resolution issue. Interesting your remark that a paper with the full range would make the prints all look awfully flat in most cases, tho logic I did nor realize it.

    Now let me strain your benevolent patience with a heretical question , I will wash my mouth later too, but with a decent single malt:

    Would be an ink jet be able to bring the 10 to 12 stops in the scan file on a paper, thus exceeding a light source based system with traditional light sensitive paper ? And if so ( no reason for me to deal with the art of ink splashing tho) would we then have the flattening effect you have described ?

    Best regards,

    bertram
    A la recherche du temps perdu: www. bersac.de

  4. #4
    OldBikerPete's Avatar
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    Quote Originally Posted by rfshootist
    Dear Helen

    Would be an ink jet be able to bring the 10 to 12 stops in the scan file on a paper, thus exceeding a light source based system with traditional light sensitive paper ? And if so ( no reason for me to deal with the art of ink splashing tho) would we then have the flattening effect you have described ?
    I have printed color negs traditionally and to HP 4-color inkjets after scanning. In my experience, the ability of the inkjet to render contrast is less than chemical processing. In a comparison of 'best practice' photographic print compared with a 'best practice' inkjet print off the same negative - using all of the contrast range available, the photographic print produces a 'snappier' product.
    The ability to attractively render highlights and deep shadow is also reduced with the inkjet print.
    As a result of these the inkjet is not able to render a contrasty negative as well as photosensitive paper.
    If the contrast on the negative is beyond the ability of the photo paper to handle, there are techniques available to allow rendering of most subjects effectively. These are extremely exacting and time-consuming. The Photoshop equivalents performed on a scanned negative are much faster and probably higher quality, producing an acceptable inkjet print which is probably better than most attempts using photo paper.
    Digital printing onto photo paper is different again and something I have yet to try.

  5. #5

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    Most modern color negative emulsions (that would be the Kodak and Fuji lines) have about the same dynamic range as B&W negative films. That is, they can record just about any real-world subject brightness range (SBR) without color shifting or shouldering.

    The largest I've done was with 160PortraVC. According to my Pentax digital spot meter, I went Zone III to Zone XI with detail, so about 11+ stops (the scene was a white flower in direct sunlight in the middle of the day in the middle of June in the Northern Hemisphere). The film did it's job perfectly. I'm guessing it could handle 12 stops with ease.

    As Helen rightly points out, this would be a tough negative to print in the darkroom. So... I didn't. I drum scanned it and printed it with an inkjet (I know, blasphemy!). The reason for this abominable behavior is that scanning takes this huge density range on the film and makes a perfect fit to the ink range on the paper.

    Don't look at me like that. This is the same thing that we do with the Zone System (more or less). In the Zone System we use the film as an intermediary between the SBR and the dynamic range of the paper. In the case above, we would use severe contraction development (N-4 or so) to haul down the density to make the negative easy to print.

    Same thing - different method.

    Anyway, to answer the question asked, really contrasty slide films like Velvia have a lower dynamic range - say 5 stops. Less contrasty slide films have a higher dynamic range, say 6 stops. Modern negative films, both B&W and color, have essentially unlimited dynamic range, say 12 stops. All of this is in my humble experience and is in no way arrived at scientifically and is not meant to be authoritative. And all that.

  6. #6
    rfshootist's Avatar
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    Quote Originally Posted by OldBikerPete
    In my experience, the ability of the inkjet to render contrast is less than chemical processing. In a comparison, ............the photographic print produces a 'snappier' product.
    The ability to attractively render highlights and deep shadow is also reduced with the inkjet print.
    As a result of these the inkjet is not able to render a contrasty negative as well as photosensitive paper.
    This is interesting to read because it is 100% congruent with an information I got from a friend today who does inkjet printing and traditional printing too.
    He says that especially the pigment based inks would close earlier then photo paper tho the file offers about 10 stops from a good consumer scanner with 4,2D = 1:1000 density.
    The whole thing is an academic discussion only for me anyway, just a peripherical consideration for the main issue which made me posting her. I've given up the idea to print my own colour photos with an inkjet, since quite a while, the more I learned of inkjets the more I saw that this isn't what I would like to deal with now , for a lot of reasons.

    Regards and thanks for the input !

    bertram
    A la recherche du temps perdu: www. bersac.de

  7. #7
    Helen B's Avatar
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    Though it isn't something that belongs here: there is a very wide range of qualities of inkjet print. It is possible to have a noticeably greater density range with a colour inkjet than with a chromogenic print. The way in which shadows and highlights are rendered in an inkjet print is not an inherent property of the ink/paper combination, it is controlled by a combination of things like the input file, the ink settings and the printer profile. The wide density range is there, how it is used it is up to the person printing.

    Best,
    Helen

  8. #8

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    Kodaks professional photo books indicates that color print paper well is suited for a log densuty range of 1.00 without considering the extremes. C41 films have a gamma of nearly .6..it varies by film. Therefore, ignoring the extremes, a range of densities provided by the subject of 1.66 could be covered (1.0/.6). The number of stops is 5.5 (1.6/.3)... .3 is the commonly used log of 2..2 being the difference made by a stop.

    You can get a wider density range on the negative but this is what a straight forward well made print can handle.
    Claire (Ms Anne Thrope is in the darkroom)

  9. #9

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    Claire! While the gamma of C41 film is around .6 the gamma of color printing paper is around 1.8 to 2.0. So you still ended up of only a range of only about 3.3 stops. So with the compression/expansion you don't get more dynamic range but rather a lot of latitude.

  10. #10

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    Are you indicating that RA 4 paper will be incapable of providing a density range of 1.00?

    Are you indicating that with straightforward methods that RA 4 paper when
    exposed from a color negative negative that received normal processing and and was given an appropriate exposure to a scene containing 5.5 stops will not be able to print it satisfactory manner?
    Claire (Ms Anne Thrope is in the darkroom)

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