Expose for shadows, develop for higlights

Discussion in 'Exposure Discussion' started by haris, Nov 1, 2005.

  1. haris

    haris Guest

    Well, this will sound really stupid from my side, but...

    I never understood what that rule means. Yes I know that is one of oldest and firmest rules, but I never used it on purpose. So I would really love if someone explain it to me practically.

    I belive exposing for shadows means that I measure light in shadows to get details in shadows (or not to have details if I don't want), but what developing for higlights means? For example if I use Ilford ID11 and FP4, at Ilford recommended 8:30 minutes developing time, how practically to use mentioned rule, how and why to change developing time?, les say for portrait, and let say that I use two lights one with f22 and other with f16 and time 1/125 (shooting condition only as example, not real condition, I am interesting in learning how practically to using the rule, not for one time shooting advice asking). Some guidance, please.

    Thanks.
     
  2. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    The basis of this principle derives from two facts--

    1. If you don't use enough exposure to get the shadow detail on film, no amount of chemical manipulation will get that information back.

    2. As you increase development time or temperature, highlight density increases much more quickly than shadow density. So much so that for practical purposes, you can consider the shadow density to remain almost constant, whatever the development time. This also means that you can't really increase film speed by increasing development time, as is commonly believed.

    This means that you should test your film and developer to see how much exposure you need to record sufficient shadow density in any given situation, and you can test the effect of development time to determine how much development you need to produce detail in the highlights for your printing process in any given lighting situation.

    There are a number of ways to determine the amount of contrast in any given scene. I prefer the Zone system described in Ansel Adams' _The Negative_, which uses spot metering. Some prefer to use incident metering, as described in _Beyond the Zone System_, and there are other approaches as well.

    This is mainly aimed at photographers using natural light.

    The situation you are describing is a studio situation. In the studio, I don't use the Zone System to determine development time, because it is possible to control the contrast of the scene directly by controlling the light, so I use an incident meter with a diffusion dome, control the light ratio by controlling the output and position of the lights, and always develop for "normal" contrast.
     
  3. FrankB

    FrankB Member

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    I had problems with this too (despite having it explained to me by a lot of very patient people) until I read John Blakemore's darkroom workshop book.

    Highly recommended.
     
  4. Les McLean

    Les McLean Subscriber

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    Exposure is the key to recording sufficient detail in the shadows and film development provides the contrast control and density of the highlights. I will break down the saying " expose for the shadows and develop for the shadows" as follows:

    To understand the logic of what I am about to describe you must understand how all meters work. They are calibrated to 18% mid grey, therefore whatever you take a meter reading from will be rendered as mid grey in the print unless you make the necessary adjustment to the exposure you use. Because shadows are generally darker than mid grey it is necessary to adjust the reading given by the camera. Some photographers place all landscape shadows on Zone III which is TWO stops less than mid grey but some, including me, place landscape shadows on Zone IV which is ONE stop less than mid grey. The choice is yours, I would suggest that you try both and use what suits your taste.

    In order to record shadow detail you need to accurately meter the darkest shadow and adjust the metered reading down by ONE or TWO stops. For example, if the meter reads 1/60th @ f11 you would expose at either 1/125th or 1/250th both at f11 to expose correctly to record detail in the shadows.

    The next step is to determine the range of contrast in the subject you are photographing, for this will determine how you will develop the film. My rule is that if the contrast range is below 3 stops I will underexpose the film by one stop, after I have adjusted for the shadow exposure as described above, and increase film development by 25% which equals ONE stop or even by twice 25% which equals TWO stops.

    If the range of contrast is 3 to 5 stops I will develop the film normally. If the range of contrast is greater than 5 stops I will increase exposure and reduce development but opposite to the description given for a low range of contrast.

    More development means higher contrast and less development means lower contrast.

    To calculate increased or reduced development the following will help:

    Assume that normal development is 10 minutes. To increase by ONE stop calculate 25% of 10 minutes which is 2.5 minutes therefore the adjusted devleopment time will be 12 mins 30 seconds. To increase by TWO stops the calculation must be done in two steps. First calculate the increase for ONE stop as above and then calculate for TWO stops by starting with 12 mins 30 secs as the development time, 25% is 3 mins 15 seconds therefore the development time for an increase of TWO stops will be 15mins 45 secs. To calculate reduced development you would deduct 2mins 30 secs from 10 mins giving a time of 7 mins 30 secs for ONE stop. 25% of 7 mins 30 secs is approx 1 min 45 secs therefore the development time for a TWO stop reduction in development would be 5 mins 45 secs.

    I hope this helps and is not too complicated to understand, if you need further explanation please PM me and I'll be happy to help further.
     
  5. panchromatic

    panchromatic Member

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    I recently got Les' book "creative black+white photography" and he has excellent examples of what he describes here, Not to mention a very large amount of other awesome information.
     
  6. haris

    haris Guest

    Thank you all for fast and detailed informations.

    Les, if I remember correctly, I belive you wrote same (or simillar) explanation like this in Practical Photography magazine few years ago, and I remembered it only when read it again now. And I understood it even then. Of course I know how meter works, and I know that if, for example, I use spot meter metering shadows, I must compensate (use faster shutter speed) for getting correct exposure. What I didn't understand was part of developing. But, I do understand now practical using of mentioned rule, and now go to practice.

    Well as I use roll film (120 and 35mm), not single shhet films, I belive this will be more difficult to do, but I will try fo figure out how.

    And, Les, don't be afraid, if I ever need it, I will be so selfish to use your generous offer :smile:

    Regards
     
  7. FrankB

    FrankB Member

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    Yep, I'll very happily recommend that book too!

    Worth the price purely for the case studies. The other ton-and-a-half of indispensable information comes as a bonus... :smile:
     
  8. JHannon

    JHannon Member

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    The book is a must have and as you can see, Les is an excellent teacher.
     
  9. haris

    haris Guest

    And that is also thing which I never understood.

    I know that I can use for example ISO100 film as ISO200 and then change developing time acording to change of film speed (in fact using slower film as faster film). Or to use ISO100 as for example ISO50 film. That I know, and I did that.

    For example in box of EFKE ISO100 film is written that under tungsten light obtained speed is ISO50, and under flash lights obtained speed is ISO100. Is that means that under tungsten lights I must to use that film as ISO50 film (set my meter for using ISO50 film)?

    But I never understood what means using ISO100 film as ISO100 and "changing its speed" with development? I read about it, but I don't understand concept of using film at its native speed, and obtaining different speed with developing. What is reason for that

    Is using ISO100 film as ISO200, and changing developing time acording to that, same as using ISO100 film as ISO100 and increase its speed with developing (even if you David said it is wrong thinking that is possibile, me too don't see logic in that).

    Thanks and regards.
     
  10. zenrhino

    zenrhino Member

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    Have you done film speed tests with your preferred film/developer/camera(meter) combo? That's the first place to start. Get everything calibrated and then start changing stuff.

    Somewhere on these forums (Im at work and dont have it bookmarked) is a pair of articles that explains this to the nth degree.
     
  11. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    Film speed is measured in terms of shadow detail. In general terms, the question is--what is the minimum amount of exposure needed to produce a visible increase in density over unexposed film (film base+fog). In Zone system terms, one measures film speed by seeing how much exposure is needed to produce a Zone I density of 0.1 (though you may decide that with a certain film/developer combination, a higher Zone I density produces better shadow separation). The ISO film speed is measured in a similar way, using a specific developer (that you would probably never want to use for normal photography) under very controlled conditions.

    If you increase development time with your normal developer, the highlights will increase in density, but Zone I will stay in about the same place. You might get a slight increase in speed, but generally not enough to rate a 100 speed film at 200 or 400 or 800. You will get an increase in contrast though, and you might have a printable negative, but it would be inaccurate to say that you really achieved a speed of 200 with a 100 speed film by extending development.

    It is possible to increase the speed of a film by using a different developer (like Microphen or Acufine), or a different development technique like stand development, or with certain other techniques like hypersensitizing the emulsion with ammonia vapors or pre-exposure, but you can't just increase the time and get more shadow density that way.
     
  12. Bob F.

    Bob F. Member

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    For a more a detailed understanding of how film reacts in developer you need to get a book or find a website that explains it in detail. Get Ansel Adams's "The Negative" or similar work that deals with the Zone System (ZS) as you need to understand this stuff to understand the ZS. You don't have to use the ZS, just understand where it is coming from. This includes the concept of Exposure Index (EI) which is your personal film speed for that film in that developer at that agitation, temperature and time. It is often 1/3 to 1 stop less than the manufactuter's marked speed. Comes as a bit of a shock at first!

    You do not need densitometers and such like. There are several methods of finding your EI without one: mostly by looking at prints exposed for the minimum-time-for-maximum-black exposure. You can then use Les's rules of thumb for N+/N- development. I have a few PDFs I made from articles on the late Barry Thornton's website that detail finding personal film speed etc without densitometry. As far as I know these may be copyright of his estate so I will not post them, but the original articles are still available at archive.org here: http://web.archive.org/web/20040923232629/www.barry-thornton.co.uk/ - scroll down to the bottom. Well worth a read.

    Cheers, Bob.
     
  13. noseoil

    noseoil Member

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    Haris, since you are using roll film, it will be easy to see what happens. Do a shot with your "normal" exposure and development, then change your film speed. Write down the shot number and what you did to change exposure (more light, less light).

    Once you have taken the full roll, do a "normal" development and then print what you have on a contact sheet. You will see a difference in the shots. Take a little time to study what you have in the print. If you change things by a full stop, you will see how it works. Find out what you need for shadows which have enough detail and look right to you.

    You can do the same thing with development, once you have decided which exposure works best for you. It might be 100, but it might be 50 or even 25. There is no rule for this, because everyone's equipment is different; cameras, lenses, meter, developer, paper, it all goes into what works for you. Once you have the correct exposure for your needs, development can be changed to make contrast different. Good luck. tim
     
  14. haris

    haris Guest

    Thank you all very much for all advices and answers.

    I will folow yours advices and I will try to buy recommended books. In fact I thought about those boosks before, but since I don't have credit card, it was dificult to buy them. Well, I will find the way...

    Thank you all again.
     
  15. kaiyen

    kaiyen Member

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    Haris,
    First of all, you can't change a film's speed. A film in a particular developer at a particular dilution (and even with your particular development methods) has only 1 speed. The only caveat at to that is with tungsten light, as you noticed. Film has slightly less sensitivity to tungsten light, that's all. But, other than that, it has only 1 speed.

    What you're talking about is "pushing," where you deliberately underexpose the film and then overdevelop it to get usable results. Many people think that you are increasing film speed - turning an ISO 100 film into an ISO 200 film. You are not. You are _shooting_ it at a higher EI (exposure index), but the actual, scientific film speed has not changed.

    The key word in pushing is "usable." If you take Efke 100 and shoot it at EI 200, it won't look "normal" (as defined by the look you get when shooting at EI 100) no matter what you do with developers, etc. But if you're willing to give up shadow detail, accept more grain and contrast, then you can overdevelop (push) in order to get the midtones in the right spot so that you can still print the film. Again, it's about usable results, not "normal" ones.

    allan
     
  16. MattKing

    MattKing Subscriber

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    One important qualification - when you are considering setting exposure so that a shadow area will print in Zone III or Zone IV, you need to understand that what is being discussed are shadows which include detail you wish to be able to see in the print.

    Many, if not most photographs include areas that are intended to be so dark as to reveal no detail. In Zone system terms, those areas are essentially ignored at time of determining exposure on the film - they are expected to fall into Zone 0.

    If you set exposure to put those deepest darkest shadows in Zone III or Zone IV, they and everything else will be too dense in the negative (too light in the print), your highlights will likely block up and lose detail, and you will not be making best use of the capacity of the film and/or developer.

    In my mind, the determination of which shadow to place into Zone III or Zone IV is the Zone System skill that improves the most with experience.
     
  17. Ole

    Ole Moderator Staff Member Moderator

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    Let's see...

    EFKE 100 has a non-linear response to the spectrum. Well - all films do that, but EFKE films are a bit more non-linear than most. That means that EFKE 100 has reduced sensitivity to red light, which there is a lot of in tungsten light. BTW, EFKE 50 and 25 are even more non-linear, and almost red blind.

    So in warm light, EFKE 100 is less sensitive than the light meter would indicate and needs one stop more exposure. Ilford FP4+ is just the opposite, and can be used with half a stop less exposure.

    So film speed is based on a standard spectral sensitivity, which few films follow. That means we may have to adjust exposure with changing light colour.
    -----------

    Next is the "personal speed" thingy:

    Many photographers find that exposing the film at some other speed than the box value gives them better results. This could be a consequence of their metering methods, their light meter, the developer of choise, variations in the emulsions, or just plain personal taste. This is not ISO, which is strictly defined, but EI (for Exposure Index).

    ------------
    ISO film speed is defined from the shadows - how much exposure it takes to give a certain density. Density, BTW, is "above film base density + base fog" or fb+f for short. That only means "usable density".

    So "Expose for the shadows" only means "expose enough to get some usable detail in the shadows - unless you think you want something else".

    ------------

    "Develop for the highlights" was a very good advice back in the days when all development was by inspection. It still is, for those of us who still do development by inspection!
    What the zone system is, is an attempt to give the same level of contrast control when developing by time&temperature.

    When you "push" a film you will get higher contrast, but the shadows won't gain much in density. So even if you get the midtones up by 2 steps (say from mid grey at ISO 100 to mid gey at EI 400), you still won't have increased the detail in the shadows. So developing longer in the same developer does not (significantly) incrase film speed. Using a different developer could; there are just as many speed-increasing developers as there are speed-losing developers.

    Do I make sense at all?
     
  18. Earl Dunbar

    Earl Dunbar Member

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    In addition to Ansel's books, I always found Zone VI Workshop, by Fred Picker, to be eminently useful. YMMV.

    The whole idea is to establish the workflow for a film/developer combination that is "normal", then you can vary factors from there.

    Basically, KISS ... Keep It Simple, Stupid.

    Earl
     
  19. Gerald Koch

    Gerald Koch Member

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    The easiest way to think about it is:

    Exposure determines the density of the negative.
    Development controls the contrast.
     
  20. Earl Dunbar

    Earl Dunbar Member

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    Yup. And specific developer defines tonal rendition. D-76 varies from Rodinal which varies from FG-7, which varies from Amidol, etc., etc.

    Trius
     
  21. haris

    haris Guest

    Thank you all