Delta-X was adopted for the ISO standard. W speed is more of a historic footnote for being the runner up. As the paper says, W speed "is of particular interest in the mathematical theory of the shape of the sensitometric curve and its relation to speed." It's worth knowing for that, but it has never been used as a film speed method. Seriously, film speed can be a confusing topic and W speed will only add to the confusion unnecessarily.
Originally Posted by ic-racer
Last edited by Stephen Benskin; 03-01-2013 at 02:30 PM. Click to view previous post history.