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Thread: BTZS film testing question

  1. #1

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    BTZS film testing question

    I ordered film testing in View Camera Store, just received the data yesterday and there are few things I do not get. First, I had the impression that one SBR unit is more or less equal to one Zone. However, with Zone System the test results go only to N-1 and with SBRs I have SBR 9 with the same developing time. If SBR 7 is the "same" as N why there is this difference with N- development?
    Also I am very much surprised by effecive film speed. I was testing FP4+ with Pyrocat HD, 1+1+100 and 2+2+100 dilutions, as I am printing both on Azo and bromide papers. Even with 2+2+100 and the longest developing time I got only about ASA 64 and with shorter developing times in 1+1+100 dilution the film speed was about ASA 10-20. Do you think it is correct?
    I would be most greatfull if someone of you clarifies this to me.
    Jan

  2. #2

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    Re: BTZS film testing question

    SBRs and N development are not the same. They both do the same thing - get you to a correctly exposed and developed negative, but are different ways to measure. Something like inches and millimeters.
    juan

  3. #3

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    Re: BTZS film testing question

    Quote Originally Posted by j.e.simmons
    SBRs and N development are not the same. They both do the same thing.
    juan
    This is what I understand but I thought if SBR is 9 it means that there are two stops to compensate - the same as N-2, I thought one SBR unit = one stop = one zone and it does not matter how do you measure the light. So they both would be inches. Am I rigth?
    Jan

  4. #4

    Re: BTZS film testing question

    Quote Originally Posted by Jan_6568
    I ordered film testing in View Camera Store, just received the data yesterday and there are few things I do not get. First, I had the impression that one SBR unit is more or less equal to one Zone. However, with Zone System the test results go only to N-1 and with SBRs I have SBR 9 with the same developing time. If SBR 7 is the "same" as N why there is this difference with N- development?
    Also I am very much surprised by effecive film speed. I was testing FP4+ with Pyrocat HD, 1+1+100 and 2+2+100 dilutions, as I am printing both on Azo and bromide papers. Even with 2+2+100 and the longest developing time I got only about ASA 64 and with shorter developing times in 1+1+100 dilution the film speed was about ASA 10-20. Do you think it is correct?
    I would be most greatfull if someone of you clarifies this to me.
    Jan
    Expose as recommended from the test data with real photographs. Proof all of the negatives and then you will be in a position to ascertain the validity of the data. I would bet that it will be spot on. Check back with us and let us know how this iteration goes for you. I invested in the Metrolux and the software myself and BTZS has allowed me to achieve optimal results to the point where I am concentrating more on the image and less and less on the technical aspects of the process and that is the best scenario for any photographer IMO.

    Cheers!

  5. #5

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    Re: BTZS film testing question

    Quote Originally Posted by Jan_6568
    I ordered film testing in View Camera Store, just received the data yesterday and there are few things I do not get. First, I had the impression that one SBR unit is more or less equal to one Zone. However, with Zone System the test results go only to N-1 and with SBRs I have SBR 9 with the same developing time. If SBR 7 is the "same" as N why there is this difference with N- development?
    Also I am very much surprised by effecive film speed. I was testing FP4+ with Pyrocat HD, 1+1+100 and 2+2+100 dilutions, as I am printing both on Azo and bromide papers. Even with 2+2+100 and the longest developing time I got only about ASA 64 and with shorter developing times in 1+1+100 dilution the film speed was about ASA 10-20. Do you think it is correct?
    I would be most greatfull if someone of you clarifies this to me.
    Jan
    As for film speed something is definitley wrong, either with the exposing or development procedure or with the developer. I consistently get an EFS of aroudn 125 with FP4+ and Pyrocat 1:1:100.

    If I were you I would expose a sheet of film outside with the sun out. Rate the film at EFS 125. Take an incident reading in the sun and another in the shadows (open shadows, not deepest) and average the readings for your basic exposure. Develop the film for about 12-14 minutes with constant or intermittent agitation. When dry, look at the shadow detail. If you have some detail in the shadows the film and developer combination are giving rated fim speeed. If that is the case, something is wrong with the testing. If not, something is probably wrong with the developer.



    Sandy King

  6. #6

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    Re: BTZS film testing question

    Quote Originally Posted by Jan_6568
    This is what I understand but I thought if SBR is 9 it means that there are two stops to compensate - the same as N-2, I thought one SBR unit = one stop = one zone and it does not matter how do you measure the light. So they both would be inches. Am I rigth?
    Jan
    You may be right, depending on your methods, but you probably are not. I have not found an SBR to equal a Zone or N. In my experience, they measure the same thing, but use a different scale. Also, if you read Phil Davis deeply, you'll find where he talks about how Zone placement makes a difference - if you place a scene on Zones III to VIII, for instance, you should develop differently than if you placed the scene on Zones II to VII, even though both measure the same contrast range.

    I found it much easier to put Zones aside and concentrate on SBRs alone until I figured out more of what I was doing.

    Maybe it's easier to think of SBR and N as being something like Celsius and Fahrenheit - measuring the same thing with different scales.

    Try Michael and Sandy's suggestions to test your film speed question. I haven't used FP4+ with BTZS yet.
    juan

  7. #7

    Re: BTZS film testing question

    One thing that has not been mentioned is that the VCS does seem to understand the use of staining developers very well. They might have read your negatives with the visible channel instead of the blue channel for silver. I know they do not have a UV densitometer which is what would have been more appropiate for the 2:2:100 for the Azo readings.

    If the readings were taken correctly then I think the most likely reason for the problem is a mistake in processing. There is no way that a 1:1:100 would give you a 10 to 20 EI with FP4.

  8. #8

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    Re: BTZS film testing question

    Quote Originally Posted by Jorge Gasteazoro
    One thing that has not been mentioned is that the VCS does seem to understand the use of staining developers very well. They might have read your negatives with the visible channel instead of the blue channel for silver. I know they do not have a UV densitometer which is what would have been more appropiate for the 2:2:100 for the Azo readings.

    If the readings were taken correctly then I think the most likely reason for the problem is a mistake in processing. There is no way that a 1:1:100 would give you a 10 to 20 EI with FP4.
    I was talking to Fred about reading 2+2+100 negatives and he said it is all right to read the blue channel (he was quoting Dick Arentz). As the 2+2+100 test were done some time ago (I only received 1+1+100 yesterday) I am not sure about 1+1+100 readings. However, I did some field tests based on 2+2+100 results. The film speed for normal development VCS gave me was ASA64 but I rated FP4 ASA100, developed according to the test results and I would say the negatives were a little overexposed. I had some detailes where I placed zone II. When I tried rating FP4 ASA 80 for N+1 development the negative was really overexposed, at least one stop.

    I do agree it is very strange to get so low speed. I think the processing was correct, as I processed other FP4 negatives (rated as 100, as I usually do) along the test negs. and they were fine. This would suggest that my Pyrocat was fine (I use premixed one in a liquid form I get from Formulary). I basically did what Sandy suggested, but I will repeat the field test exactly as he says.

    Jan

  9. #9

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    Re: BTZS film testing question

    Quote Originally Posted by j.e.simmons
    You may be right, depending on your methods, but you probably are not. I have not found an SBR to equal a Zone or N. In my experience, they measure the same thing, but use a different scale. Also, if you read Phil Davis deeply, you'll find where he talks about how Zone placement makes a difference - if you place a scene on Zones III to VIII, for instance, you should develop differently than if you placed the scene on Zones II to VII, even though both measure the same contrast range.
    Juan,
    I think (or I hope , I understand what happenes to the Zones when you develop N+ or N-, but as far as I understand the effect Phil Davis describes depends on the zone span you use for measuring. So before the measurement is done the "test data" do not know wheteher I used Zone III and VII or II and VIII thus it is not possible to consider this effect a priori. I am not sure if I am right - if not correct me please.

    Jan

  10. #10

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    Re: BTZS film testing question

    Quote Originally Posted by Jorge Gasteazoro
    One thing that has not been mentioned is that the VCS does seem to understand the use of staining developers very well. They might have read your negatives with the visible channel instead of the blue channel for silver. I know they do not have a UV densitometer which is what would have been more appropiate for the 2:2:100 for the Azo readings.

    If the readings were taken correctly then I think the most likely reason for the problem is a mistake in processing. There is no way that a 1:1:100 would give you a 10 to 20 EI with FP4.
    Jorge,

    I am curious why you suggest that the reading for AZO should be made in UV mode and not Blue?

    AZO does indeed have considerable sensitivity in both the UV and Blue wavelengths and it seems to me that one could make a case for plotting curves in either mode. I have considered both and done some testing both ways, without reaching any conclusions as to which is best. I may have been confused in results because in fact the RD-40 flood that I used for the tests actually puts out a lot of UV light, a fact I did not anticpate or cover for. I verified this by printing with the RD-40 through a UV cut-off filter that eliminated all blue light from the equation, and the resulting printing was almost as fast as with the RD-40 with no filter. Exposures are also extremely fast on AZO with a 20 watt BLB spiral fluorescent.

    And yet, some folks use a 300 watt RD-40 flood to print AZO!! What gives? Are these folks just grossly over-exposing their negatives? Not MAS of course because he is exposing through Super-XX film that is over fifteen years old and has a very high B+F. But why would anyone using in-date film with normal B+F need a 300 watt bulb to print AZO?


    Sandy
    Last edited by sanking; 8-Sep-2006 at 14:03.

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