Leica M9-P vs Leica Q2: read noise comparison

The Leica M9-P was measured at 6 ISO settings from ISO 80 to ISO 2500. Values were derived by Bill Claff from DxOMark lab data.

At base ISO (80) read noise is 9.58 DN. Read noise keeps falling across the measured range, so the camera isn't fully ISO-invariant there.

The Leica Q2 was measured at 11 ISO settings from ISO 50 to ISO 51200. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (50) read noise is 2.50 DN, or 8.8 electrons at the sensor. From ISO 800 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 1600 don't change analog gain (digital push). Full well at base ISO is about 55,703 electrons; unity gain is around ISO 180.