Quote Originally Posted by Stephen Benskin View Post
... the closest agreement over the greatest range of conditions with the print judgment speed.

Attachment 65821
Again, Nice graph.

So the 0.1 density is the poorest of all and yet is the basis of traditional Zone System tests.

This is where I come to the conclusion for myself... I base my EI speed on 0.1 density of the curve that meets ISO conditions closest...

Then I take Stephen's example in the Delta-X Criterion paper as proof of "approximate invariance of speed" (my quotes), to justify not changing my speed regardless of the developing time I choose.

I do the tests for any particular film/developer combination - to find the closest ISO curve and take its speed. The rest of the curve family gives me Time/CI which I use to fit development time to shooting conditions.