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  1. #21
    Bill Burk's Avatar
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    Quote Originally Posted by Thomas Bertilsson View Post
    Effectively this really means that the longer you develop your film the more contrast you get. The correct way of saying what's implied by 'expose for shadows, develop for highlights' would be 'expose for shadows, develop for contrast'. That makes it much easier to think about, and to understand that your two main controls are film exposure and developing time.
    This whole post by Thomas Bertilsson is a very clear summary, and is purely helpful

  2. #22
    Bill Burk's Avatar
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    I'll try a different explanation for the fun of it...

    It's kind of like tape recording music. If you don't get close enough to the singer, no amount of amplification will help, you will just hear hiss. Maybe you'll hear a little of the singer when they're being loud. That's underexposure. Move the mic in and that is exposing for the shadows. Now turn up the gain. That's developing. Crank it up to the point of distortion and that's like "blocking the highlights".

  3. #23
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    Quote Originally Posted by Bill Burk View Post
    I'll try a different explanation for the fun of it...

    It's kind of like tape recording music. If you don't get close enough to the singer, no amount of amplification will help, you will just hear hiss. Maybe you'll hear a little of the singer when they're being loud. That's underexposure. Move the mic in and that is exposing for the shadows. Now turn up the gain. That's developing. Crank it up to the point of distortion and that's like "blocking the highlights".
    As someone who does live sound for fun sometimes, this is a great analogy.

  4. #24
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    Quote Originally Posted by jsimoespedro View Post
    Hi all,

    I get this expression often on the web: "Expose for the shadows, develop for the highlights".
    I understand what exposing for the shadows means, that is straightforward. But then, what to do in the development stage.

    Example: Assume to have shadows at -1 stop, mid-tones and 0 and highlights at +1. If exposing for the shadows, I give a +1 stop compensation, right? But then what should I do on the darkroom.

    For instance, if use a ISO100 film, shadows were shot at EI50. Should I now reduce development time to bring down highlights? Is that it? If yes, at what EI should I development the film, given the -1/0/+1 example.

    Thanks!

    (I am loving this forum, btw)
    Click image for larger version. 

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    Exposure for the shadows is a mantra because you need a certain minimum amount of light to hit the film in order to get over the threshold where they will develop. The shadows areas on a negative receive the least amount of light from the scene and are closest to clear after development. In the attached diagram this is close to 1 on the relative log side of the graph.

    Adjusting EI from 100 to 50 moves all your subject matter to the right. Shadow detail from the scene that may have been at 0.9 and not depicted on the negative at EI 100 may now be at 1.2 and visible at EI 50.

    That doesn't mean it will print yet though. The area between the red lines represents what might straight print on grade 2 paper. (That is not actually a fixed area, it is controlled by enlarger exposure and paper grade. It is normal though to have preferred settings for printing that you target, so for this example I will assume the lines are that target.)

    Lets follow the black line for a second. At about 1.3 on the relative log scale negative density reaches a point where it will stops printing black and starts printing shades of gray and at about 2.8 it reaches the point where it stops printing shades of gray and only paper white shows.

    In this example your camera exposure has to be able to get the negative to 1.3 before the print will care.

    You have to test for yourself to figure out where this point is for yourself.

    As you can see from the three curves on the graph the bottom end is a bit like a hinge on a door, ISO and EI ratings are all basically ways to know where that hinge is.

    The three curves represent changes to development (same exposure), blue is more development (N+), black is normal (N), green is less (N-). Notice that the hinge point doesn't change much. At this end of the scale exposure is king.

    When you increase camera exposure all the subject matter moves right and following the curve. New subject matter rises out of the black past the lower red line into the printable area. The problem is though that at the upper red line highlight detail does the same thing moving up and out of the printable range.

    Reducing negative development, green line, allows us to keep some of that highlight subject matter from moving out of the printable range. At this end of the scale development is king and provides real control.

    Hence, expose for the shadows and develop for the highlights.

    Even though this is quoted as mantra by many, it is a special case. It completely ignores any preferences we might have for say mid tone contrast. It's basis is sound but it's use must be tempered by experience.

    The most usable portion of the saying is to expose for the shadows. If you don't reach the lower exposure threshold on the negative there is simply nothing there to develop.
    Last edited by markbarendt; 01-15-2014 at 07:31 AM. Click to view previous post history. Reason: Fix attachment
    Mark Barendt, Ignacio, CO

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

  5. #25
    Toffle's Avatar
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    Nicely put, Mark.
    Tom, on Point Pelee, Canada

    Ansel Adams had the Zone System... I'm working on the points system. First I points it here, and then I points it there...

    http://tom-overton-images.weebly.com


  6. #26

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    Quote Originally Posted by Bill Burk View Post
    This whole post by Thomas Bertilsson is a very clear summary, and is purely helpful
    This now makes perfect sense. Film manufacturers release charts plotting contrast vs. development time.

  7. #27

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    Quote Originally Posted by markbarendt View Post
    Click image for larger version. 

Name:	Image.jpg 
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ID:	80214

    Exposure for the shadows is a mantra because you need a certain minimum amount of light to hit the film in order to get over the threshold where they will develop. The shadows areas on a negative receive the least amount of light from the scene and are closest to clear after development. In the attached diagram this is close to 1 on the relative log side of the graph.

    Adjusting EI from 100 to 50 moves all your subject matter to the right. Shadow detail from the scene that may have been at 0.9 and not depicted on the negative at EI 100 may now be at 1.2 and visible at EI 50.

    That doesn't mean it will print yet though. The area between the red lines represents what might straight print on grade 2 paper. (That is not actually a fixed area, it is controlled by enlarger exposure and paper grade. It is normal though to have preferred settings for printing that you target, so for this example I will assume the lines are that target.)

    Lets follow the black line for a second. At about 1.3 on the relative log scale negative density reaches a point where it will stops printing black and starts printing shades of gray and at about 2.8 it reaches the point where it stops printing shades of gray and only paper white shows.

    In this example your camera exposure has to be able to get the negative to 1.3 before the print will care.

    You have to test for yourself to figure out where this point is for yourself.

    As you can see from the three curves on the graph the bottom end is a bit like a hinge on a door, ISO and EI ratings are all basically ways to know where that hinge is.

    The three curves represent changes to development (same exposure), blue is more development (N+), black is normal (N), green is less (N-). Notice that the hinge point doesn't change much. At this end of the scale exposure is king.

    When you increase camera exposure all the subject matter moves right and following the curve. New subject matter rises out of the black past the lower red line into the printable area. The problem is though that at the upper red line highlight detail does the same thing moving up and out of the printable range.

    Reducing negative development, green line, allows us to keep some of that highlight subject matter from moving out of the printable range. At this end of the scale development is king and provides real control.

    Hence, expose for the shadows and develop for the highlights.

    Even though this is quoted as mantra by many, it is a special case. It completely ignores any preferences we might have for say mid tone contrast. It's basis is sound but it's use must be tempered by experience.

    The most usable portion of the saying is to expose for the shadows. If you don't reach the lower exposure threshold on the negative there is simply nothing there to develop.
    Excellent explanation.

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