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  1. #11

    Join Date
    Dec 2004
    Shooter
    ULarge Format
    Posts
    194
    My guess is that the ND-filter is indeed a 4-stop filter, when the negatives are not way underexposed. In that case it's Kirk made the right analyses.
    The underexposure is probably caused by not compensating for the reciprocity factor of your film. Starting with F11 and 1/30, closing down to F22 would give 1/8. Adding a red filter (2.5 stops) would give something like F16.5 at 1/2 sec. Adding the ND filter for 4 stops should give F16.5 at 8 sec, or F22 at 12 sec. This time should be compansated for to about 20 sec. using TMax100.

  2. #12

    Join Date
    Jan 2005
    Location
    Wilmington NC
    Shooter
    Multi Format
    Posts
    18
    Thank all for responding. Did a very simple test this morning...tmax 100/120 at F16 metered without filters at 1/125. My red filter is optimum at -2 stops or F16 at 1/30. Adding ND filter (bayonet mount) to red and assuming the -4 stop assumption; F16 at 2 sec. Bracketed roll, same image (contrasty sunny and shadow) went from -4 stop to -12. -6 stops (using both filters) was detailed but would be difficult to print (underexposed). -12 was still detailed though overexposed. I found -10 to be dead on. Which would make it a -8 filter in my test...I guess. Dev in Rodinal at 1:50 for 13 min.

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