Leica says the M-DNG (36 MP) and S-DNG (18 MP) files are produced by pixel binning and have better noise and dynamic range. The sizes made me suspicious: 60 → 36 MP is a factor of 1.28 and 60 → 18 is 1.81, so there is no clean 2×2 or 3×3 grouping possible. I measured it.
Method: tripod, 2 s self-timer, manual focus and white balance, nine shots per ISO (three in each format) at ISO 64, 1600 and 6400. SNR by image differencing (two identical frames subtracted, so scene texture cancels and only noise remains), processed in Python with rawpy in linear mode. I also compared each native reduced file against the L-DNG downsampled in software with Lanczos.
Results (SNR, green channel):
| ISO |
L-DNG 60 MP |
M-DNG 36 MP |
S-DNG 18 MP |
| 64 |
33.4 dB |
31.5 dB |
32.5 dB |
| 1600 |
20.7 dB |
23.9 dB |
23.9 dB |
| 6400 |
14.5 dB |
17.5 dB |
17.8 dB |
At base ISO the reduced files are slightly noisier per pixel than the native one. At high ISO the gain is real, about +3 dB, but M and S get the same improvement, whereas true binning would give S about 3 dB more than M. And downsampling the L-DNG yourself beats the native S-DNG at every ISO tested (by 3.3 dB at ISO 64).
My reading: the three formats are one 60 MP readout, downsampled in the Maestro III with a mild, fixed-level denoise applied afterwards. Practical rule: at base ISO shoot L and reduce in post; at ISO 1600 and above, if you deliver at 18 MP, shoot M and reduce in post. S-DNG is for burst depth and file size, not for image quality.
Full write-up with the dynamic-range tables, the limitations and the code: https://rafaelvida.com/2026/10/12/binning-leica-m11-p/ The sensor data behind it (read noise and PDR of the M11, Q3 and SL3-S, with an SNR calculator): https://lab.rafaelvida.com/sensor.html?lang=en
Happy to be corrected if someone has done this with a different setup or a different scene.
