"Bob Monaghan" wrote in message
...

Hi again Mike ;-)

No, I'm going the reverse way. I am saying that 6 MP is interpolated to
make a decent 8x10" print, and that the underlying data is circa 40 lpmm
....

Hi, Bob. Yes, I'm good with all that, even PopPhoto's 100+ lpmm. No problems
with that here. Farther in the thread, I think we individually satisfied
ourselves that these are all reasonable numbers, and matches our personal
experiences.

How can that be? The total system resolution is given by:

1/R = 1/R1 + 1/R2 + ...

Reasonable ranges for the combined resolution for the enlarger + paper --
about 60 lpmm to 80 lpmm -- gives results that are in line with what I've
seen. It also matches very well with what I see in film scans: about 3400
dpi is required to match that same total system resolution.

In short, all three systems -- 6 MP dSLR, scanned 35mm, and optical prints
from 35mm -- produce roughly equal quality results when printed at 8x10.
Optical prints on a well aligned enlarger will do slightly better, and
direct digital trails slightly behind very carefully scanned film. I find
the convergence of accepted industry data, information theory, and personal
experience quite satisfying.

What do you think? Is this horse well and truly flogged at last?