[erick]

Testing the shadow tells you the film speed. The "official" film speed tests use the shadow too. The meter relates film speed to gray Zone V.

It made more sense to me, now.

When building the density x exposure graph, many of us use a 21-step Stouffer wedge, each step is a half f/stop. This gives plenty of information about everything from the shadow to the highlight. When done, you have a graph that tells you the density you get for the exposure.

I didn't know this "21-step Stouffer wedge" method, but I will do some research, then.

There isn't a scientific way to match a paper to print on or to pick paper grade based on density of a negative. But developing your negatives so that they "fit" on a middle grade of paper gets you a negative that is possible to make a good print from.

Maybe I was looking for something too scientific, in fact. But I guess the average system will work in most of the cases. Only through massive experimentation it is possible to have a more accurate control over the final result.