Here are results from a side-by-side comparison of the Leica M10-P ($8,795) vs. the new Leica M10 Monochrom ($8,295) by Onasj (see all previous posts by Onasj):
Test conditions:
You can download all the files (JPGs, DNGs, 100% enlargement matrixes) here.
Summary: as expected, for monochrome images the M10M handily beats the M10P in terms of much lower noise AND much more detail. In terms of background noise, after scaling the M10P or M10M images up or down to the same size (41 MP or 24 MP), I see about a 1.5-stop noise advantage for the M10M. In terms of “usable” high-ISO image quality for monochrome images, I would set my personal threshold around ISO 18,000 for the M10P, and around 50,000 for the M10M (also a 1.5-stop advantage for the M10M). But the surprise, for me, was that in terms of capturing subject detail, the combination of higher resolution, lack of a Bayer CFA, and (my guess) a better sensor even on a per-unit-area basis together resulted in the M10M at ISO 25,000 capturing as much or more detail in the subject than the M10P did at any ISO. Of course, if you are shooting street photography, kids running, dreamy portraits, etc. the subject detail capture level difference probably won’t matter. But if your goal is to capture subject detail and black and white is acceptable, this is the most capable M body to date in my opinion.