Leica Q2 MONOCHROM vs Leica S: read noise comparison

The Leica Q2 MONOCHROM was measured at 11 ISO settings from ISO 100 to ISO 102400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 1.68 DN, or 10.3 electrons at the sensor. From ISO 3200 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 96,875 electrons; unity gain is around ISO 610.

The Leica S was measured at 5 ISO settings from ISO 100 to ISO 1600. Values were derived by Bill Claff from DxOMark lab data.

At base ISO (100) read noise is 7.26 DN. From ISO 200 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise.