I remember the kit. It convinced me I needed to spend more on a decent enlarger lens!

I don't think you can separate all the variables. You CAN test one thing at a time, with all other variables kept equal.

At some point, you have to just accept what you have, learn its characteristics and limitations, live within them, and not fret over how good something else is (or might be). There are plenty of folks who obsess over every last bit of performance on a test target, rather than getting out and making images.

In the real world, some of the most compelling photos are made with lenses that aren't particularly sharp, with cameras that aren't the "best on the market" (whatever that means). They tell stories, move minds, sell products, change hearts, or cause us to linger and take a longer look.

And we don't friggin' CARE whether they were made on film or with a digital camera, or whether they were made with a Nikon or a Canon (or any other brand) camera. We're too caught up in what we SEE to care about the technology.

The medium IS NOT the message. Marshall McLuhan was full of it. If you use any medium appropriately, you will make your point. Great gear just makes it easier and more fun.

Yes, I have seen those definitions in many places. My problem is that a line, whether black or white, must have a width. Then does a line pair mean: one dark + one white or "left side of dark + entire white to left side of next dark." Now think of film silver bromide grain size - light dissociates sone molecules and the film developes grain-wise. A grain will have many, several, few, no dissociated AgBr molecules, so a grain will be either nearly clear to very dark. So to my mind the resolution limit is grain size. Now in digital what is the grain size equivalency in pixels.

Which means, of course, that viewing an image of even the most carefully rendered test pattern under high magnification is bound to give you lines with jagged edges. It reinforces the claims that there are some comparisons that, by their very nature, are, at best, subjective. Just as you cannot definitively compare ppi to dpi without other factors, you can only estimate any comparisons between film and digital without introducing other variables. In the end, it follows the rule of apples and oranges.

This does raise an interesting question, however. Has anyone ever counted the number of grains in a film negative or slide? I'm sure there's some way to do in using an electron microscope and a computer.