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  1. #31

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    Quote Originally Posted by jdef
    Hi again Jorge. I agree that if we are discussing very general terms gradient is a better value for comparison, but when specifically discussing subject ranges, it seems that SBR could be used without all of the terminology debate. When I give an SBR value, I always include the related paper ES, and if I don't it's an error of omission and not a misunderstanding of the term.

    Jay
    I think if you are discussin subject ranges then it is going to get too confusing trying to figure out if you mean this from the actual subject or a film test. While it might be obvious to you in the general context of the message, it might no be to all of us. Why not use the terminilogy as we all learned it from Phil so that we are all in the same page?

  2. #32
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    Quote Originally Posted by Jorge
    Why not use the terminilogy as we all learned it from Phil so that we are all in the same page?
    Some of us aren't into BTZS as much as others. Why not use the terms that are used in the real world - like the recognize international terms? Like I've said before, it's fine for Davis to use any term he wishes within the BTZS community, but the use outside of the community can create confusion. That's why there are accepted terms and definitions of those terms. Those who decide on these issues don't chose them haphaserdly. There are frequently extended debates. A somewhat relevant example is with the subcommittee on colorimetry in the 1930s. It took more than 6 years for them to agree color was a psychophysical phenomenon.

  3. #33

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    Quote Originally Posted by jdef
    Jorge, take this exchange for example-




    Do you find the information provided confusing?

    Jay
    The first one yes, the second one no.

    In the first one you mixed SBR and CI interchangeably and it was confusing. The second paragraph is perfect, although I am a bit skeptical about a developer than can make HP5 get a G bar of 1.41. Without trying to piss you off, that is too big a slope for HP5 and makes me think there must be a mistake in your numbers somewhere, specially for a non staining developer, whatever this developer is....

  4. #34

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    Quote Originally Posted by Stephen Benskin
    Some of us aren't into BTZS as much as others. Why not use the terms that are used in the real world - like the recognize international terms? Like I've said before, it's fine for Davis to use any term he wishes within the BTZS community, but the use outside of the community can create confusion. That's why there are accepted terms and definitions of those terms. Those who decide on these issues don't chose them haphaserdly. There are frequently extended debates. A somewhat relevant example is with the subcommittee on colorimetry in the 1930s. It took more than 6 years for them to agree color was a psychophysical phenomenon.
    I can only respond that most of us here are familiar with the BTZS, and not familiar with the more rigorous terms you are using. I dont know about anybody else here, but I cannot "place" units like meter/candle/second as well as log units.
    OTOH one would hope that a discussion like this would encourage someone to try a more methodological approach to exposing and printing. The BTZS does that very well, they would have to read 10 or more books to understand the terminology you use. In my case, tha alphabet soup you use is totally confusing. The BTZS has 4 important basic abreviations, SBR, G bar, ES and DR that are easily correlated... LESR, LER, etc, etc. are unfamiliar and do not "register" with me, I get stuck thinking "now, what the hell was LESR?"....

    Bottom line Beskin, you are the only one using this terminology in this forum, the rest of us are using the BTZS one. Right or wrong that is the way it is...

  5. #35

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    Quote Originally Posted by Jorge
    OTOH if you say " I develop this film to a G bar of .76" then regardless of the ES we are individually using, we all can relate the results to our own experience.
    THis still has the problem of not matching the development to the printing process. We do know exactly how much development was given, but it will print completely different in regular silver, AZO,... But that's OK is we just mention our target material.

    I do have to wonder how we did determine that the film was developed to a G-bar of 0.76 though... unless that particualr sheet of film contained a step wedge with a proper, full range of exposure.

  6. #36
    Stephen Benskin's Avatar
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    Quote Originally Posted by Jorge
    Bottom line Beskin, you are the only one using this terminology in this forum, the rest of us are using the BTZS one. Right or wrong that is the way it is...
    Jorge my name is included with all the posts. It's Benskin. While I don't think "because everyone else is doing it" is a good argument, I am more than capable of coverting the BTZS terms, but I cannot personally use something I feel is incorrect. So please give me the same consideration and allow me the right to use the terminology I am most familiar with. Maybe we can both learn something new. Thanks.

    I cannot "place" units like meter/candle/second as well as log units


    BTZS mostly uses relative log-H if I'm not mistaken. Meter Candle Seconds is the antilog of log-H. Meter Candle Seconds are used in calculating film speed and, well, exposure, i.e. B&W film speed equation is 0.8 / Hm where Hm is in mcs.

  7. #37

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    Quote Originally Posted by jdef
    In the interest of concensus and precision, how do we refer to SBR values as a function of development, If everytime I give SBR data derived from a film test someone remarks that SBR only applies to the scene? Is there no way to discuss this data without getting into these kinds of terminology debates? Should there be some differentiation of the terms used for SBR in the scene and SBR as derived from a film test?
    Jay, as we know, I'm no expert on BTZS, but I'll give it a try anyway!

    Just keep in mind that all those BTZS graphs we are looking at where there is a SBR value given on the graph, located next to the amount of development, calculated with G-bar, the exposure scale (ES) of the printing material has been used in the calculation of the SBR. So the SBR values on the graphs, have the ES incorporated into it, they are inseparable.

    So it is consitent to label the graphs with the SBR - but when we talk about it, we need to make sure we mention the ES as well.

  8. #38

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    Quote Originally Posted by Kirk Keyes
    THis still has the problem of not matching the development to the printing process. We do know exactly how much development was given, but it will print completely different in regular silver, AZO,... But that's OK is we just mention our target material.

    I do have to wonder how we did determine that the film was developed to a G-bar of 0.76 though... unless that particualr sheet of film contained a step wedge with a proper, full range of exposure.
    Sorry, but you are wrong, at least when we talk about the BTZS. Once again, to use the numbers you posted in the other thread. For an ES of 1.05 you had an SBR of 2.6, for an ES of 1.45 you had an SBR of 3.6, yet for both the G bar was 1.31. with the relation G=ES/SBR, you can adjust wichever way you want.

  9. #39

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    Quote Originally Posted by Stephen Benskin
    Some of us aren't into BTZS as much as others. Why not use the terms that are used in the real world - like the recognize international terms? Like I've said before, it's fine for Davis to use any term he wishes within the BTZS community, but the use outside of the community can create confusion. That's why there are accepted terms and definitions of those terms. Those who decide on these issues don't chose them haphaserdly. There are frequently extended debates. A somewhat relevant example is with the subcommittee on colorimetry in the 1930s. It took more than 6 years for them to agree color was a psychophysical phenomenon.
    What you apparently fail to understand, or refuse to recognize, is that there *is* no internationally accepted term for SBR as it is explained and used in Davis’ BTZS system. SBR, as Davis uses the term is not the same as LSLR. SBR only has meaning within the specific reference of the BTZS system of exposure and development with an incident meter. It is based on an assumption, i.e. that the subject luminance range can be estimated by adding the illuminance range (which is the difference between readings measured with an incident meter in the most brightly lit area the scene and in the shadow areas of the scene) to the 5-stop luminance range. It can not be called the same thing as LSLR because, as you yourself have correctly stated, LSLR can only be measured directly with a reflectance meter, not with an incident meter.

    BTZS and the Zone System are both closed, self referencing systems. Each has a language with meaning only within the context of the system. What, for example, would the concept of zonal placement mean to someone who, though a master of sensitometry, knew nothing about the Zone System?

    Sandy

  10. #40

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    Quote Originally Posted by Jorge
    with the relation G=ES/SBR, you can adjust wichever way you want.
    I was trying to point out that, better explained with your equation, rearrainged a bit, that SBR=(ES/G).

    So I think what I was trying to say was "you have to state both ES and G to correlate it with SBR". (Thanks for reminding me of the formula.)

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