DOF Question, non-mathematically

[Pere Casals]

...that depth of field given how much the negative is to be enlarged...

I'd add that it also depends on the CoC we want to tolerate in the print itself !!!

We may want 6 lp/mm on a 2m print to view it with the nose on it, or perhaps we can tolerate 2 lp/mm because the print anyway has to be viewed from at least 1m far...

Why am I mistaken?

I guess this is a rethoric question

It would be hard to find mistakes from you, Dan, possibly some are there, but they are well hidden !