As the fractional gradient / Delta-X speeds don't change as quickly with development as the fixed density speeds (which aren't supposed to be used beyond the ISO parameters), the overall negative density will tend to increase and decrease in comparison to the fixed density negatives. This is one of the primary arguments against the idea of the just black printing approach for anything other than normally processed negatives.
Originally Posted by markbarendt
How will Delta-X change the example? It wouldn't. The ISO standard uses Delta-X Criterion. That's why the US agreed to the change.
Apart from the greater tendency of what Jones calls "first choice prints" is more likely under certain printing conditions, I can't see a problem attempting to peg a certain density at a certain point on the curve. As long as the photographer has customized it to their materials and personal preference. A specific target negative density; however, shouldn't be considered universally applicable. Take the two quad example. What makes it a correct exposure for the ISO is not the negative density at the metered exposure point, but that the metered exposure was at 8/ISO and the exposure fell at the correct ratio from the speed point.
In the scientific photography papers, phrases like "greater tendency" and "more likely" are used a lot. Most methodologies will work adequately. The question is always about the one which has better results most often. This doesn't mean that in certain situations another method will work better. Just that in most situations, one method tends to have a higher consistancy. The question of fixed density vs fractional gradient is about what is more accurate over the greatest number of situations. It's all one big normal distribution curve. Advocating one approach over another is only about what is more likely.
Last edited by Stephen Benskin; 04-04-2013 at 12:01 PM. Click to view previous post history.