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  1. #11

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    Quote Originally Posted by jdef
    Unless I've read it wrong, Kirk's question has to do with measuring low SBR scenes, and not developing film.
    Jay, you're right. I was asking about how to meter in those situations.

    And if anyone is interested, I've gotten Xtol 1+1 at 20C with Fuji Acros to process to an SBR of 2.8 with a bit of base+fog, and to SBR of 3.0 with B+F of only 0.10 - so processing the film to those levels is definitely not a problem for me! Someday I'll try Xtol undiluted and save some time!

    So I guess the bottom line is I would just have to guess with the incident meter/BZTS metering, or use the spot meter as I did.

  2. #12
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    Kirk,

    I don't want to take this thread off in a different direction, but the idea of how to address short luminance ranges would make for an excellent new thread. After all, there's more choices on how to deal with different luminance ranges than just processing and each choice has a distintive aestetic influence.

  3. #13

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    Quote Originally Posted by Kirk Keyes
    Last year, I was in Death Valley, trying to take photos of patterns in the sand. I've got one of those newer Minolta Flashmeter VIs that can do both incident and reflected measurements. I used the spot meter while there and some of the scenes were only about 3-4 stops (reflected) between the darker and lighter portions of the scene. Using Acros and Xtol, I was able to develop the film enough to expand it out to where it prints well.

    Today, I was flipping through my copy of the BTZS book (3rd Ed.), and I thought back to the Death Valley stuff. So I was looking for a description of how to meter scenes of low contrast using BZTS. Using an incident meter, it looks to me that the BZTS system can't measure scenes that have SBR's less than 5. It also seems that it can't differentiate between a 5 SBR scene and a 3 or 4 SBR scene.

    I know you can determine development times for SBR ranges this low, but how do you actually measure them with and incident meter. Does photographer's discretion (i.e. override meter readings) kick in here?

    Kirk

    The important thing to understand about the scene you describe is that neither a reflected reading nor an incident reading will give you the correct exposure to reproduce the tonal values as you want them without interpretation. In other words, whether you use the Zone system or BTZS you have to make interpretative decisions as to how you want to the tones in the scene to reproduce on your print. You understand this with the Zone system and know how to accomplish what you want so no point to comment further about this.

    But what about BTZS. If you use an incident meter the reading will suggest an SBR of 5, and the reading will be the same regardless of where you point the meter. Such a reading if developed for an SBR of 5, will give you an overexposed and underdeveloped print. You will have a lot of detail in the shadows, with good separation, but muddy blacks. You can do one of two things to approximate an SBR that will suggest better exposure and development. One option is to go to one of the shadow areas of the scene and take a meter reading at that spot, note how much this EV values differs from the EV value of the first reading, and subtract from the SBR of 5 to give you a new SBR value, which could be 3 or 4. If there is not a real shadow area large enough to use for the reading you can simulate the shadows by shading the cone of the meter, take a reading, and then do the same calculation as above. Base exposure on an average of the shadow (or shaded) reading and the reading taken in full light. Or you could just double the EFS of the film and make the exposure based on the shadow reading.

    Development is another issue. Most developer/film combinations will easily allow for development of SBR values of 5 or less with regular silver gelatin printing, where the desired CI is about 0.60 and the exposure scale of the process is about 1.10. However, with AZO #2 and alternative processes, where the desired CI for the negative is 0.75 or even higher, and the exposure scale of the process is 1.5 or higher, the practical reality is that very few films are capable of development for a SBR of less than 5. So in a scene such as the one described by Kirk, unless you happen to be using one of the films that will allow a CI of up to 1.15 or 1.20 you are just as well off to expose and develop for the SBR of 5 and make adjustment with the process for more contrast. And the problem is not the developer, but the fact that most films have a maximum CI so that no matter how long you develop, or high much energy your developer has, the film reaches a point beyond which further contrast is not possible.



    Sandy
    Last edited by sanking; 04-13-2005 at 06:59 PM. Click to view previous post history.

  4. #14

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    Quote Originally Posted by Kirk Keyes
    Mark - where do you live?
    I live in North eastern AZ. The only thing I have found to combat the very low SBR is early morning, or late afternnot light. Shooting rock art is a PIA and have yet to get one that looks good.
    Technological society has succeeded in multiplying the opportunities for pleasure, but it has great difficulty in generating joy. Pope Paul VI

    So, I think the "greats" were true to their visions, once their visions no longer sucked. Ralph Barker 12/2004

  5. #15

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    Quote Originally Posted by Kirk Keyes
    Jay, you're right. I was asking about how to meter in those situations.

    And if anyone is interested, I've gotten Xtol 1+1 at 20C with Fuji Acros to process to an SBR of 2.8 with a bit of base+fog, and to SBR of 3.0 with B+F of only 0.10 - so processing the film to those levels is definitely not a problem for me! Someday I'll try Xtol undiluted and save some time!

    So I guess the bottom line is I would just have to guess with the incident meter/BZTS metering, or use the spot meter as I did.

    Possibly we are not using the same terminology...I can go understand that might be the case...but how in the world did you determine your SBR numbers of 2.8 and 3.0?

    Your terminology indicates that you are processing to the stated SBR...that is erroneous if that is what you are intending to say. SBR is a measurement of the lighting contrast in the scene when the exposure is made...not something to be processed "to".

    The correct termininology consistant with BTZS procedure would be developing to a desired CI based on the SBR of the exposure.
    Last edited by Donald Miller; 04-13-2005 at 06:19 PM. Click to view previous post history.

  6. #16

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    Quote Originally Posted by jdef
    Unless I've read it wrong, Kirk's question has to do with measuring low SBR scenes, and not developing film. Regarding film/developer combinations for extreme expansion development, I think there is some mythology at work in some of the admonitions bandied about. I can get an SBR of 3.3 with HP5+ and Defehr Rapid Universal developer in 3 min/70F, with very low B+F.

    Jay
    What do you mean that you can get an SBR of 3.3 with HP5+ and your developer? I remember you saying that you had read the BTZS book. Where does it express developing film to a given SBR?...SBR is a measurement of scene contrast and the correct terminology is to develop for the SBR inherent in the exposure. Never have I heard of anyone who is knowledgeable in BTZS express a SBR in tenths...

    Do you have a densitometer to measure these results that you are claiming? I would be interested in seeing the curves that you have plotted for this degree of expansion.

  7. #17

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    Quote Originally Posted by Donald Miller
    What do you mean that you can get an SBR of 3.3 with HP5+ and your developer? I remember you saying that you had read the BTZS book. Where does it express developing film to a given SBR?...SBR is a measurement of scene contrast and the correct terminology is to develop for the SBR inherent in the exposure. Never have I heard of anyone who is knowledgeable in BTZS express a SBR in tenths...

    Do you have a densitometer to measure these results that you are claiming? I would be interested in seeing the curves that you have plotted for this degree of expansion.
    Donald,

    Although Davis does not give any examples in Beyond the Zone System, at least so far as I can recall, of SBRs below 5, some of his examples of metering for unusual lighting conditions appear to recognize that they are possible with incident metering. I have discussed the issue with a number of fairly knowledgeable persons who use BTZS, including Dick Arentz who uses both Zone System and BTZS, and many of us believe that BTZS does in theory allow for SBR values below 5, as in the situation Kirk described. And in fact, Davis' own plotter program does graph SBR values below 5.

    Sandy

  8. #18

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    Quote Originally Posted by Donald Miller
    The correct termininology consistant with BTZS procedure would be developing for a given SBR.
    I've made a spread sheet that performs the calculations as layed out in the book.

    Thanks for the correction on the terminology. And your sentence above is exactly the kind of terminology I was trying to convey in the "CI of blank film" thread recently. You CAN develop film to a given SBR, just as you can develop film to a given CI. Even if the film didn't recieve a full range of exposure, like in the case of low contrast scenes - say 3 or 4 SBR, or even scenes with no contrast, such as a blank sheet of film.

  9. #19

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    Quote Originally Posted by sanking
    ...and many of us believe that BTZS does in theory allow for SBR values below 5, as in the situation Kirk described. And in fact, Davis' own plotter program does graph SBR values below 5.

    Sandy
    Most cetainly! There is no believe required. It's just a matter of making development tests out to times that allow the film to expand out to cover such low contrast ranges. (THat is, if possible - it is not with all film and paper combinations. I'm using regular silver paper and those are what I am discussing here).

    I may be mistaken, and feel free to correct me, but when I was flipping through my 3rd ed. BTZS book, I saw several graphs that have values down to 3 SBR. And look at the graphs at the bottom of this BTZS web site page:
    http://www.btzs.org/Articles/PSP.htm

    If I remember how to read these, the 16 min development for this film yields a film would match a SBR of 3.4. The G-bar at this point is 0.98. The instances I gave for the Acros above both had gradients greater than 1.00, and hence SBRs of around 3.

    It's just a matter of making an accurate meter reading for these situations. The film testing part is simple.

  10. #20

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    Quote Originally Posted by sanking
    Donald,

    Although Davis does not give any examples in Beyond the Zone System, at least so far as I can recall, of SBRs below 5, some of his examples of metering for unusual lighting conditions appear to recognize that they are possible with incident metering. I have discussed the issue with a number of fairly knowledgeable persons who use BTZS, including Dick Arentz who uses both Zone System and BTZS, and many of us believe that BTZS does in theory allow for SBR values below 5, as in the situation Kirk described. And in fact, Davis' own plotter program does graph SBR values below 5.

    Sandy
    Sandy,

    I have no doubt that this is true. I have made a number of photographs where the SBR was below 5. My concern with the posts that preceded were that the terminology in two cases indicated development "to" a certain SBR...Those statements indicated something apart from my understanding of BTZS. My understanding is that SBR is a measurement of the inherent contrast in a given exposure. That this inherent contrast (SBR) is the determining factor for the degree of development the negative receives to achieve the CI that the printing material/process requires.

    I have difficulty believing that anyone metering a scene will arrive at a 2.8 SBR or a 3.4 SBR or any other numerical value expressed in whole and decimals. The terminology is still indicative of a misunderstanding on someone's part. I don't know who it is that is misunderstanding.

    In addition, Kirk Keyes posted the following after your post and I quote:

    I've made a spread sheet that performs the calculations as layed out in the book.

    Thanks for the correction on the terminology. And your sentence above is exactly the kind of terminology I was trying to convey in the "CI of blank film" thread recently. You CAN develop film to a given SBR, just as you can develop film to a given CI. Even if the film didn't recieve a full range of exposure, like in the case of low contrast scenes - say 3 or 4 SBR, or even scenes with no contrast, such as a blank sheet of film.


    I would like your thoughts on the information as it is presented here. Either I am missing something by a mile or this makes absolutely no sense.

    I look forward to your response to this.

    Donald Miller

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