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  1. #31

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    Quote Originally Posted by Jorge
    Hmm...seems to me you have modified the BTZS method to fit your particular way of working. Other than using Phil's formula to translate "zone" readings into SBR readings I have not heard of another useful method.

    Is this how you ar egtting your SBR readings? by converting zone readings with Phil's formula?
    A few points.

    I use reflected readings for calculating N values but only incident readings for calculating SBR values. Calculating SBR values from reflected readings or N values from incident readings might work with some subjects but with most scenes it would involve some type of conversion factor that would make exposure determination very complicated and prone to misinterpretation. Which is one of the reasons I use the Expo/Dev program for figuring exposures -- you choose either the SBR or N system and the program does the rest.

    About the SBR of 4, there is no such thing. All subjects that are evenly illuminated (assuming no glare or flare) will fit into a five-stop luminance range, which is two stops less than the normal SBR of 7. Thus, for all practical considerations an SBR of less than five is impossible. Even a real five is highly unusual as in even the flattest of lighting situations I rarely encounter scenes with SBRs of less than 5.5.

    Finally, one of the dangers in working with either the N system of SBR sysem is misinterpretation which can lead to an exaggeration of the difference in luminance in the scene and to inflated values, both high and low. A typical example with the SBR system, for example, would be in an outdoor scene in full sun but with some deep shadwos( as in say a recess in a boulder). If you were to meter the deepest shadows of the recess your readings would provide a SBR that is greater than it should be and this will cause you to both over-expose and under-develop your film.

  2. #32

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    Yes I do modify my readings a bit (because I use a spot meter to get to my SBRs) in order to avoid wrong exposure. It depends on the absolute values that I get. To give one example: I would expose differently for an EV range of 11 - 15 as opposed to 7 - 11. If I were to give both scenes the same exposure I find that I overexpose (still, better than underexposure) on the latter. I would give the first one an SBR of 9 and the second one an SBR of 7. I adjust my SBRs based on the overall level of contrast in a scene. It is not fool proof but that just makes it more fun.

    Sandy, how do you avoid this misinterpretation of inflated values? Is it simply a matter of careful selection of the high and low areas?
    Francesco

  3. #33

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    In any case, my original mistake was using an extremely low dilution of Pyrocat HD on Classic 200 for a scene that really did not need it. I also underestimated the time needed for the film to develop at such an extreme dilution. So far it seems that Classic 200 likes the 2:2:100 dilution much more than the others I have tried (1:2:100, 1:1:100). Does this mean that Classic 200 is an excellent film for PtPd?
    Francesco

  4. #34

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    Just tried Classic 200 (rated 200) on a neg exposed for SBR = 10 and Pyrocat 2:2:100. I used very gentle agitation on BTZS tubes for 5 mins and the results were stunning! Also did SBR = 9, 6m30s and had same success.

    Thinking of giving Classic 400 a shot using the same guidelines. Any thoughts or experiences?
    Francesco

  5. #35

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    Quote Originally Posted by Francesco
    Just tried Classic 200 (rated 200) on a neg exposed for SBR = 10 and Pyrocat 2:2:100. I used very gentle agitation on BTZS tubes for 5 mins and the results were stunning! Also did SBR = 9, 6m30s and had same success.

    Thinking of giving Classic 400 a shot using the same guidelines. Any thoughts or experiences?

    For the same conditions try increasing development time with the Classic 400 about 15%.

  6. #36

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    Thanks Sandy. Will do. I will expose for the rated film speed of 400. I love the way Pyrocat allows for the use of the rated film speed.
    Francesco

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