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  1. #11

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    There is no actual equivalent. It would be more or less a combination of exposure and contrast. The post above explains the levels control quite well. Analog photographic materials do not work quite the same way. Even more confusing, you are trying to get a positive from a negative, so some of the things you learned for exposing film are backward. Silver gelatin materials have a certain threshold exposure below which you don't get any image. In printing, you need to expose enough so that the highlight detail is properly visible. This is more or less like setting the white point in PS. Then you adjust the contrast so that you get a full range of tones from shadows through midtones to the whites. This is like setting both black point and scale. Sometimes you have to adjust exposure some more to get the balance, however. In fact, most people try to find an exposure level that pretty well covers the picture by using test strips, and then they adjust the contrast and fine tune the exposure to get a full range print.

  2. #12
    hadeer's Avatar
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    One could look into the zone system or buy a Stopclock/Analyzer from RH Designs.
    Have you seen the light..?

  3. #13
    David A. Goldfarb's Avatar
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    Quote Originally Posted by RalphLambrecht View Post
    Moving the white slider is setting the highlight exposure. Moving the black slider is the equivalent of changing the paper contrast (filtration). Moving the gray slider, on the other hand, is like switching to a different film/dev/paper/dev combination.
    Exactly.
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  4. #14

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    Quote Originally Posted by RalphLambrecht View Post
    Moving the white slider is setting the highlight exposure. Moving the black slider is the equivalent of changing the paper contrast (filtration).

    I agree with this statement once the film has been developed. But, it seems to me that the most important controls we have for B&W are 1. proper exposure combined with 2. variable development times.

    With digital, varying the exposure will only move the curve to the right or the left in the levels box. It will not change the distance from the white point to the black point (unless you clip the highlights or shadows). That is done in post, with levels, which has the effect--in layman's terms--of stretching the curve to fit the black and white points. In B&W, we set the shadows with proper exposure and then expand the curve or contract it through development of the negative to match the paper.

  5. #15
    stradibarrius's Avatar
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    Thanks for some great answers and explanations. Ralph, your explanation makes sense and is simple. Thanks for answering the question and understanding that I am interested in learning more about my analogue photography and growing my skills in the darkroom. Understanding the spirit of the question.
    I expected to get some responses that I shouldn't be asking this question here????
    "Generalizations are made because they are generally true"
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  6. #16
    markbarendt's Avatar
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    Quote Originally Posted by RalphLambrecht View Post
    Moving the white slider is setting the highlight exposure. Moving the black slider is the equivalent of changing the paper contrast (filtration). Moving the gray slider, on the other hand, is like switching to a different film/dev/paper/dev combination.
    Great description!

    I know it's not a direct comparison but burning and dodging could be considered as moving the the middle slider around, in a localized sense.

    In this sense, and yours, it applies to both color and B&W.
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  7. #17
    henk@apug's Avatar
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    Quote Originally Posted by stradibarrius View Post
    I expected to get some responses that I shouldn't be asking this question here????
    I am just wondering if it makes sense to think "digital" in the wet darkroom.

  8. #18

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    Quote Originally Posted by RalphLambrecht View Post
    Moving the white slider is setting the highlight exposure. Moving the black slider is the equivalent of changing the paper contrast (filtration). Moving the gray slider, on the other hand, is like switching to a different film/dev/paper/dev combination.
    Good grief, Ralph. Are you saying that digital and analogue may be, gulp, analogous...?

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  9. #19
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    Quote Originally Posted by henk@apug View Post
    I am just wondering if it makes sense to think "digital" in the wet darkroom.
    There was a news story this year about a virus in some plants that was reported in the news media as spreading "like a computer virus." Of course in fact it is spreading like a real virus which is what it is! Sadly it seems that digital analogies are now closer to the front of the consciousness of most people these days.
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  10. #20
    David A. Goldfarb's Avatar
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    Most of the Photoshop tools were developed to mimic analogue techniques, so I think it makes perfect sense to use those concepts to explain traditional darkroom work to people who are coming to film from digital. There's no reason that you couldn't use a densitometer to plot a histogram of a print or a negative, and I suspect that Photoshop users might have a better idea of what digital unsharp masking is, and they might better understand the concept of sharpness in general, if they knew something about the analogue process of unsharp masking.
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