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Thread: BTZS testing procedure

  1. #1
    45-57-617
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    BTZS testing procedure

    Evenin' all,

    In the BTZS procedure Mr Davis calls for development times for the film of 4, 5.6, 8, 11 and 16 mins.

    Can I use times around my previously determined 'normal' instead ?

    I determined that Pyrocat-HD at 1.5:1.5:100 and 20 C, FP4 @ ISO 64 and 4.5ml per sq inch for 12mins15secs with slow constant agitation (4-6 rpm on the tank) produced a CI of around 0.47. I would like to use this 12min15secs as the mid-point of the BTZS tests.

    That is 6:07mins, 8:40mins, 12:15mins, 17:20mins and finally, 24:30mins

    Can I do that or do I need to use Phil Davis times? Perhaps it doesn't matter a whit coz the software would sort it all out ...

    Hmmmm...

    If I were to use other chemistries would I go ahead and find a CI of 0.47 for each film and developer combination prior to doing BTZS testing for that combo ? I'm going to give the EcoPro XTOL replacement a try and also some Rodinal at 1:50 both with FP4 at this stage.

    Cheers,

    Steve

  2. #2
    Claes Uhnér
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    Re: BTZS testing procedure

    With the caveat that I have not tested this myself - I believe that you can use whatever development times you like in plotter for windows.

  3. #3

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    Re: BTZS testing procedure

    Quote Originally Posted by uhner View Post
    With the caveat that I have not tested this myself - I believe that you can use whatever development times you like in plotter for windows.
    Correct, Winplotter will allow any combination of times you want to use. For most film testing I use a standard similar to what Phil Davis recommended, but if you know in advance that the film/developer combination is going to produce low contrast or high contrast it makes sense to adjust the times to either compress or expand the range so that you can learn as much as possible from the tests.

    Simple B&W transmission densitometers can be purchased for not much money on ebay. If you plan to test film you should really do it the right way, otherwise one just winds up expending a lot of time and energy to no good end.

    Sandy
    http://www.sandykingphotography.com/
    For discussion and information about carbon transfer please visit the carbon group at groups.io
    [url]https://groups.io/g/carbon

  4. #4
    45-57-617
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    Re: BTZS testing procedure

    Thanks guys,

    I have the Xrite 361T with Stouffer and an 811 is on the way. I appreciate the fact that I am whistlin' Dixie without some reference!

    If the software is going to do a fair amount of interpolation would one go to the extremes that Phil Davis does? Given that my 'N' is 12:15 and my 'N-1' is 11:15 and my 'N+1' is 13:20 it seems to me that the idea of dropping to 6:07 and expanding to 24:30 is rather extreme.

    Furthermore, if one is using a very active developer this would be even more the case would it not ? Take a Rodinal for example. I'm not sure there would be much left after 24 mins in Rodinal going by what I understand is a very active developer.

    What happens with a developer that oxidises on agitation ? The oxidisation would play around with things would it not ?

    Cheers,

  5. #5

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    Re: BTZS testing procedure

    Quote Originally Posted by swmcl View Post
    Thanks guys,

    I have the Xrite 361T with Stouffer and an 811 is on the way. I appreciate the fact that I am whistlin' Dixie without some reference!

    If the software is going to do a fair amount of interpolation would one go to the extremes that Phil Davis does? Given that my 'N' is 12:15 and my 'N-1' is 11:15 and my 'N+1' is 13:20 it seems to me that the idea of dropping to 6:07 and expanding to 24:30 is rather extreme.

    Furthermore, if one is using a very active developer this would be even more the case would it not ? Take a Rodinal for example. I'm not sure there would be much left after 24 mins in Rodinal going by what I understand is a very active developer.

    What happens with a developer that oxidises on agitation ? The oxidisation would play around with things would it not ?

    Cheers,
    Great that you have those densitometers. I actually got this thread confused with another one where someone was trying to do BTZS testing but did not have a densitoemeter.

    The information derived from testing at the extremes can be useful in providing exposure and development information for a very wide range of subject brightness. Oxidation is of course a factor.

    Sandy
    http://www.sandykingphotography.com/
    For discussion and information about carbon transfer please visit the carbon group at groups.io
    [url]https://groups.io/g/carbon

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