Leica Q3 vs Leica S: read noise comparison

The Leica Q3 was measured at 14 ISO settings from ISO 50 to ISO 102400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (50) read noise is 1.56 DN, or 6.3 electrons at the sensor. From ISO 25600 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 51200 don't change analog gain (digital push). Full well at base ISO is about 31,135 electrons; unity gain is around ISO 200.

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.