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Thread: BTZS film testing question

  1. #1

    BTZS film testing question

    Hi,
    I did a test on TMAX 100, developed in HC 110. I followed the BTZS procedure, and plotted the data in the "Plotter" software as per instruction. I ended up with a very narrow SBR range 3.1 to 4.3, and a chart of EFS versus N numbers, ranging only from N + 2 to N+3.
    Can anyone help me out as to why the narrow ranges?

    I did a simlar test with the same film, but with D-76, and the SBR range is quite a bit wider, 4 to 11.3, and it plots the N ranges from N-4 to N+2.

    Fred

  2. #2
    よろしくお願いします! Andrew O'Neill's Avatar
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    Re: BTZS film testing question

    You are exposing the film under an enlarger, correct? I witnessed the same thing until I made an in-camera exposure of a target (zone board) in my darkroom. Much better contrast range. I should add that at the same time Xtol came out and I switched to it.

  3. #3

    Re: BTZS film testing question

    Hi Andrew,
    Yes, I used my enlarger to expose the film. What kind of lighting in your darkroom did you use on the step tablet? Can you light it with the enlarger, or did you use the ambient light source in the dark room? Perhaps it helps to place the step tablet on a light table?

    Fred

  4. #4

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    Re: BTZS film testing question

    For BTZS testing the correct way is to expose the step wedges is under the enlarger or using a sensitometor [Jorge knows the name as he has one]. In camera will introduce a miriad of problems. Uneven light coverage and flare. You will not get correct BTZS information. Phil Davis never recommended that as it could not be relied on to give reliable information. The problem with your results is probably due to the developer dilution, usually too high [strong] and as such the 4 minute step wedge is producing a too short SBR. This is then reflected on each of the next step wedges as development time increases.

    Cut your dilution in half and do the tests again . HC110 is a very aggressive developer and will give you possibly the results you want at a higher dilution.
    I would recommend D76. I hated it until I tested it with BTZS methods and suddenly found what a wonderful developer it really is.

    The other question? Have you established your own personal speed point based on your system?

    If you want an ExpoDev file for a particular film developer combination and have the ExpoDev software Phil Davis did extensive tests that are extremely accurate.

    I am happy to talk to you or others on Skype about BTZS testing or methods. Just PM me and we can make a time.

  5. #5
    よろしくお願いします! Andrew O'Neill's Avatar
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    Re: BTZS film testing question

    I gave up on the step tablet and made a Zone Board as outlined in Gordon Hutchings' book, The Book Of Pyro. I use a 500W daylight balanced bulb which sits in a reflector at the top of the board. My spot metre is used to spread the zones out one stop apart. It really is a neat way to test film for EI and all you N's. Night or day, rain or shine.

  6. #6
    よろしくお願いします! Andrew O'Neill's Avatar
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    Re: BTZS film testing question

    Personally I never did understand why you would want to test your film "outside" of the camera. Isn't "inside" the camera better? I mean, you do photography with film "inside" your camera...

  7. #7
    よろしくお願いします! Andrew O'Neill's Avatar
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    Re: BTZS film testing question

    I should add that a colleague of mine tapes his step tablet to the film (which has been loaded into a holder) and does his tests "in camera". Focus the camera at infinity toward a daylight balanced bulb and make your exposures. You will have to test to see what the correct exposure would be first.

  8. #8

    Re: BTZS film testing question

    Quote Originally Posted by Andrew O'Neill View Post
    Personally I never did understand why you would want to test your film "outside" of the camera. Isn't "inside" the camera better? I mean, you do photography with film "inside" your camera...
    No it is not, you are testing for film behavior under controlled conditions (or at least as controlled as possible). Once you have the information you can adjust it to take into account flare, shutter errors, etc. In fact, I dont know why you test in camera.....testing is supposed to be about one variable at the time, not 4 or 5.

  9. #9

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    Re: BTZS film testing question

    Quote Originally Posted by Andrew O'Neill View Post
    I gave up on the step tablet and made a Zone Board as outlined in Gordon Hutchings' book, The Book Of Pyro. I use a 500W daylight balanced bulb which sits in a reflector at the top of the board. My spot metre is used to spread the zones out one stop apart. It really is a neat way to test film for EI and all you N's. Night or day, rain or shine.
    Andrew the OP was asking about BTZS testing. You seem to be unaware of the true methodology involved. The Hutchins zone board may work well for you which I have no doubt but the presumption that any testing method can be applied to another process doesn't do justice to any system.

    BTZS requires that you use the system as intended. And when you do it is truly remarkable.

    I suppose it is like trying to use a workshop manual for a Volkswagen to repair a Porche - they are both cars, with engines and wheels but that is where the similarities end. Both do their tasks very well but no the same.

  10. #10

    Re: BTZS film testing question

    Quote Originally Posted by Fred Braakman View Post
    Hi,
    I did a test on TMAX 100, developed in HC 110. I followed the BTZS procedure, and plotted the data in the "Plotter" software as per instruction. I ended up with a very narrow SBR range 3.1 to 4.3, and a chart of EFS versus N numbers, ranging only from N + 2 to N+3.
    Can anyone help me out as to why the narrow ranges?

    I did a simlar test with the same film, but with D-76, and the SBR range is quite a bit wider, 4 to 11.3, and it plots the N ranges from N-4 to N+2.

    Fred
    Most likely you made a mistake mixing the HC110 solution. HC110 is a very energetic developer as sold and if you mix it according to Kodak's suggestions you get what you got. The same thing happened to me. Did you make sure you were using the stock and not the concentrate? If you are using the concentrate and if I recall correctly my best solution was 1:64 (one part concnetrate to 64 parts of water)...try this and see if it helps. You enlarger exposures are probably correct since you have obtained accurate result with other film/developer combination.

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