Hope you don't mind, but I played a little with your image and it appears shadow detail isn't all that bad. The image just appears to have been printed heavy. The negative should have even more and would be a better way to evaluate the exposure.
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That is an incredible mischaracterization of the ISO standard. What made Jones' testing unique is that for the first time instead of basing a method on what was assumed important from a sensitometric perspective, Jones began with the end result of the photographic process and worked backward. From L.A. Jones and C.N Nelson's
A Study of Various Sensitometric Criteria of Negative Film Speeds, "These series of prints were judged by 200 observers, each observer being requested to choose the first excellent print in each series. In this way, a statistical psychophysical evaluation of the effective camera speeds was obtained. It was recognized, of course, that such a method is much too complicated and laborious to permit of its application in practice and that for such a purpose, it is desirable or, in fact, imperative to find a sensitometric method to which will yield results in close agreement with those obtained by the direct psychophysical method." The results from various sensitometric methods were compared to the judged prints or to the print speeds and their correlation graphed. This is from the testing done in the 50s which lead to the 1960 standard and the use of the Delta-X Criterion, which is a short hand version of the fractional gradient method, as the speed method.
The "laboratory" aspect is to control the desired variables and limit the undesirable variables. Instead of laboratory, why not use scientific?
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That is quite a declarative statement. Where is the proof? What method did you use to compare to the ISO speeds and what is the level of confidence of its accuracy?
You refer to the Zone System a number of times so I am going to use its testing method as an example. Zone System speed point is four stops down from the metered exposure. The EI is determined when the exposure falls at 0.10 about Fb+f.
The metered exposure for a given speed setting, creates an exposure of 8/EI at the film plane. The black and white speed point of 0.8/EI or 0.8/H
m falls 10X to the left, or Δ1.0 log-H. Four stops is equal to Δ1.20 log-H. That means, testing the same film will result in film speeds 2/3 of a stop different between the two methodologies.
Many Zone System users recommend rating the film at ½ the ISO speed. The third of a stop discrepancy from the 2/3 stop can easily be attributed to inaccuracies in testing or simply rounding. When adjusting for the difference in methodologies, any Zone System test resulting in speeds ½ to 1 stop below the ISO speed actually indicates the film is achieving ISO speeds.
That’s why it’s important to state the testing method or more precisely the interpretation method. With ISO speeds, simply using ISO before the speed indicates the standards were followed.