Originally Posted by
Stephen Benskin
Sorry, I spent around two hour writing a post and when I went to upload it, the site had logged me off and I lost 95% of it. All that survives is the bit of intro below. Not really in the mood to redo tonight.
For any speed or contrast methodology to be relevant, the psychophysical nature of the photography must be considered. This is what Jones did in with The First Excellent Print test. He established a criterion of excellence for the photographic image, and established the definition of exposure.
Jones concluded negative density is not a practical criteria for determining quality. Contrast is, or more accurately, film gradient. More specifically quality is determinant by the gradient of the toe in relation to the overall gradient of the film. This conclusion came after comparing various speeds methods with the test print judgement speeds under the greatest number of conditions with the greatest number of emulsions and degree of processing to determine the method that most accurately corresponded to the results from the prints judged to be excellent.
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