Exposure

Discussion in 'Black and White' started by brizzybunny, Oct 8, 2020.

  1. No, Adams was pretty clear that each Zone represents a film exposure difference of one f-stop. So the difference between Zone V and Zone XIII is 3 full stops. As I suggested above I think you may making the error of interchanging scene luminance vs a printed result. But I can't tell for sure how you come up with 2.5 stops.

    This doesn't really prove anything. It just indicates that there is a certain relationship between the digital camera exposure reading and the specific way the camera translates to a digital image, most likely to either sRGB or Adobe RGB (1988)? This is somewhat akin to making a print. If a different color space were used for the outout, with a different tonal response, then the blinkies would likely happen at a different offset.
     
  2. Indeed. In camera settings work more like using a different brand or type of film that 'nominally' is the same (speed, overall characteristics). There's always a difference. How that than translates to a print, and what we can do to make it more like we want it to be, is a next step.
    So there is a bit of the basic skills needed to be learned and understood. Something that instant approval on an LCD screen will not show. If only because that screen will not render colours the way other monitors and printers do.

    There really is more to this all than can be learned looking at the monitor on a camera. And it is all pertinent to getting what you are hoping to get. And it all requires experiential learning. Time, trial and error.

    Adams' zone system is a teaching tool. No matter how many steps you want to divide the range between black and white into: follow it, and you learn just about everything there is to learn about black & white photography, from choice of film, through exposure and processing, to printing.
    When you have mastered all that, you can do what Adams himself did: cheat in every way possible, to really get exactly what you are after. That is: you then will also have learned where and how it doesn't quite work and know where and how to find ways to get round that.
     
    Last edited: Oct 15, 2020
  3. +1
     
  4. James G. Dainis

    James G. Dainis Moderator

    From Ansel Adams' book The Negative, third printing, page 49:

    "We define a one stop exposure change as a change of one zone on the exposure scale, and the resulting gray in the print is considered one value higher or lower on the print scale."

    Makes sense and seems clear to me. If I change my exposure from 1/60 @ f/16 to 1/60 @ f/5.6 I am increasing the exposure by 3 stops not 2.5 stops. (A three stop exposure change and three zones by definition.)
     
  5. As I said I haven't re-read his books in a long time. I will have to look at "The Print" and see what one value higher or lower on the print scale amount to.
     
  6. I'm not sure it really serves a purpose in this discussion. The zone system is about the compression of a range from 'life' to a negative, and the subsequent expansion of that recorded range going from negative to print, and what we can do to get some control over the end result. What we can do is make exposure decisions keeping in mind also the effect of 'pushing' or 'pulling'. Et cetera. It is more complex than "1 stop difference in the scene equals 1 zone". Whether that is so or not depends on what you do after exposure, and why.

    Mentioning Adams was part of Rodeo Person's attempt at comedy. It was not pertinent and served no purpose at all except create confusion and such nonsense.
     
  7. I am not especially a believer in the zone system, but I don't think that means it isn't relevant.

    Scenes will have different dynamic range that we want to get into the negative.
    (Not always the full range of the scene, especially not if the sun is visible.)

    Scenes with large dynamic range are harder to get the original exposure right.
    Recognizing those, and knowing what to do about them, is what needs to be learned.

    Low dynamic range scenes are less of a problem, though they might be when printing.
    (That is, either from a negative or digital image.)
     
  8. The zone system is a great tool to get people thinking about the black and white proces, involves doing things (or at least trying things), and as such is at least a good teaching tool.
    This discussion however took off when a Cowboy proclaimed B&W film dead, and concerning yourself with skills to be acquired to be able to do things so you end up getting what you want superfluous, since they do not have any effect on that final result, and people looking at the final result do not care.

    Whatever can be said about that, one assertion (true or false) of said Cowboy at one point was that digital captures a larger tonal range with detail, and he mentioned Adams there. Quite irrelevant.

    Since then, this discussion veered off on tangents about Adams and what Zones are exactly.
    That is irrelevant to the topic Cowboy Person put this thread on, being whether or not it is comical to want to learn the skills you cannot do without, because a dslr's screen teaches you all there is to learn.

    By all means, delve into the zone system, and give us an account of when, under what zone system related conditions, a one stop difference in object luminance translates to a 1 zone difference in a print, and when not. (The short answer to that is: whenever you want to.)
    It is however topic drift Rodeo Clown introduced as part of his comical diversions, aimed at belittleing people who think they need to learn and understand things properly, instead of needing no more than a dslr screen and, maybe, a histogram. The poor saps... it is all too difficult as well...
     
    Last edited: Oct 17, 2020
  9. James G. Dainis

    James G. Dainis Moderator

    Note from Moderator: Comments in here are getting a bit too personal. Any more comments of that nature will result in the entire post being deleted.
     
  10. Zone system or not, this is pretty much the way exposure works.
     
    q.g._de_bakker likes this.
  11. Yikes! I never knew that "exposure" was so difficult, especially for film. I've been doing it OK, I think, for the last 50 years without too much trouble.
     
  12. Except for reversal films, most of the time it isn't all that hard.
    That is why simpler cameras work often enough. Many were happy enough with that.

    But then there are the ones that aren't so easy.

    Backlit on a sunny day.
    Indoors with meter-fooling light sources in frame.
    Flash when you need to get it right for foreground
    and background at the same time.
     
  13. No. Whether those subjects appear as a negative or a positive, their reflectivity can be objectively measured.

    Nearly all those examples that Adams gives can be pegged to quite accurate reflectance values.
    For example: White picket fences, freshly fallen powder snow, recently applied white paint, fluffy white clouds, freshly laundered white linen, white copier paper... etc. All of those surfaces have very close to a 100% Lambertian reflectance, which is measurably and mathematically only 2.5 stops above the 18% grey card standard. To place those tones on Zone 8 (white with texture) or even edging on Zone 9, as per Adams descriptions, just totally nullifies the concept of each Zone being spaced exactly one stop apart.

    It's the measurable surface reflectances of real objects that make a nonsense of the Zone descriptions, not the other way around. And that doesn't matter if you're looking at a print or a negative.
     
    Last edited: Oct 19, 2020
  14. As said (cannot remember if it was Ctein, I may be wrong), the one stop difference between zones is just... "by definition". Just this.
    Even the Zone V could be for some but not for others... it all depend on each one`s materials and testing. The Zone V is just the medium point between the zones with texture, shadows and highlights.
    The Zone System has been evolving since the very first days with Minor White. Even the number of zones changed along the time, from 7 at first to the current 11, they used a meter and applied their experience to this specific meter... (we can also argue that current zones are a nonsense). I think that (just IMHO) we must take the Zone System not as fixed rule but a practical method.

    And there is the 18% grey card thing... 18%, or... 12%... ?
    Right, Adams mention the 18% reflectance several times. And it has been teached everywhere all along the world. Now we know it could be wrong, too.
     
    Last edited: Oct 19, 2020
    q.g._de_bakker likes this.
  15. When this discussion started, the typical color wheel used by painters come to my mind.
    Everybody knows that primary colors are used to make all the colors in the spectrum; my kids learnt that they were yellow, red and blue.
    Now in a higher course at school they know they are yellow, magenta and cyan. Plain red and plain blue are not primary colors (obviously).
    So we can still argue about which cyan is primary or not... What difference does it make? The chromatic circle still works.
     
    Last edited: Oct 19, 2020
  16. Zones are not set entities, but where the photographer previsualises bits of a scene to end up to create the desired image. Zones are where the photographer wants to have selected parts of a scene end up on a print of that scene. The zone system tells us what to do to move them there. If you so wish, you can try (possibilities are limited. Hence the cheating i mentioned.) to have two parts of a scene that measure just 1 stop difference in luminance in zone 1 and zone 8 respectively. Understanding exposure, film, paper and processing is what helps you get it that way.
    The answer, thus, to how great a difference in scene luminance would constitute a 1 zone difference is: as much or little as you want.
     
  17. This proves that you do not even begin to understand what the zone system is about.
     
  18. I'm not quite following you here. When I "measure" a film negative I use a transmission densitometer; I never measure its reflectivity. Or are you talking about the reflectivity of the original scene?

    If you're talking about the original scene, ok, yes I agree that this can be measured (probably better to call it luminance, though, rather than reflectivity). But... what you referred to earlier (your post #57) was NOT the original scene; it was on the print. I know where you got those descriptions (you said page 60 in your book). Ok, if you look one page earlier in your book, you should find this, "Table 2 gives the approximate values for for various types of subjects rendered 'realistically.'" So it seems pretty clear that these descriptions are "values" for a print. They are not descriptions of the original scene.

    So again, I think you are confusing the "Zones," related to the film's exposure, with the rendered print "Values." Again, I don't see an inconsistency in Adams' Zone terminology - each Zone represents an f-stop difference in the camera exposure.

    I DO see a real vague sort of thing when he translates to print Values. But I don't know if it could be otherwise - paper "black" can differ a lot, and that sort of thing.
     
  19. For those willing to pay for an in-depth tutorial on exposure, Youtube's Nick Carver has one that might help.
     
  20. It's not correct that each zone represents a certain, fixed difference in camera exposure. You can expand and compres the luminance range to fit a desired zone difference. Film exposure and subsequent processing determine part of how big a difference that difference in camera exposure turns out to be in the negative and print. Zones represent the tone level in the print. You assign parts of the scene to zones in the print, and then do everything you need to make it so.
     
    Last edited: Oct 19, 2020

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