Quote Originally Posted by Photo Engineer View Post
Donald, the tone scale is the total length of the sensitometric curve from where the curve starts to rise above dmin (toe) to where it levels off at dmax (shoulder). If the dmax is lowered, then the shoulder is closer to the toe and the tone scale is shorter. That is the definition I learned at EK with all of the diagrams and technobabble removed.

PE
Perhaps Donald is referring to the exposure range...

I hear people often (just this last weekend actually) say pt-pd has a "longer" tonal scale, much like they say that Azo has a "longer" tonal scale. They seems to be confusing either the exposure range of the paper, or they percieving something that is not backed up by math/physics/optics.