Thanks, dnmilikan.

That's one point not clear to me:

I do the exposure series and looking at the negative I obtain my personal EI.
Now, if I print the test strip and there is no difference in paper between -0.5, base, +0.5 frames it doesn't matter.

My viewpoint is that I should use as minimum density the one that gives first dark gray above black on a normal grade paper print - not in the negative.

i can't see what's wrong with this idea.

Jorge O