Originally Posted by
Donald Qualls
Just to eliminate the silly stuff -- that sounds awfully similar to results I read about a photography student getting some years ago when testing Tri-X (the ISO 320 sheet version): EI 16. What eventually turned out to be the case was that he was loading it backward in the holders, and exposing through the antihalation layer resulted in loss of about 4.5 stops of speed.
Now, I presume, Jorge, that you aren't making that mistake (especially not with enough sheets to get completely through a test series) -- but I can easily see how a batch of film could have gotten notched on the wrong corner, i.e. upside down when the notches were cut. Shouldn't be terribly hard to check to be sure the emulsion is on the correct side on some of the developed negatives (which wouldn't even require sacrificing a sheet to look for the light and dark sides)...
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