Perhaps I'm accidentally inventing the ISO standard for myself, or at least confirming it, albeit probably with the safety factor.
Originally Posted by Stephen Benskin
Film speed as a target net density versus a reference point is an interesting issue when it comes to flare as well. I'm always told flare increases film speed. Well, in a way yes, but if the toe is flattened by flare, I haven't gained anything. In fact I've effectively lost "speed" because local contrast has been flattened in the shadows.