Gardyloo

DPI is a metric more suited to printing than scanning; however an older post I saw somewhere says my version of the Wolverine unit (the current one is rated at 20mp, mine is - I think - 12 mp) says it was the equivalent of 4000 dpi, so the current one... maybe 6667 dpi? Don't know if it's linear. Certainly it's way higher than any printer can manage, and unless you're blowing up a (35mm equivalent) image to some giant screen or poster, or cropping the bejeezus out of it then blowing it up, then standing three feet from it, you're unlikely to sense a difference between a 1000 dpi and a 4000 dpi image. Like I say, I've found the limiting sharpness factor to be the grain in the slide/negative.

There's evidently a large body of literature comparing the likes of Kodachrome 25 (which for many was the gold standard of film resolution) to digital equivalents. Most go off into deep weeds over contrast measurements, digital compression ratios... yada yada. For me, I just wanted a way to archive something like 10,000 images before the dyes on the slides fade or the silverfish eat all the mounting cardboard.