Panasonic Lumix S1R II read noise vs ISO

The Panasonic Lumix S1R II (Lumix DC-S1RM2) was measured at 29 ISO settings from ISO 80 to ISO 51200. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (80) read noise is 1.99 DN, or 8 electrons at the sensor. A second gain (dual gain) kicks in at ISO 400, cutting input-referred read noise by about 1.8 stop. From ISO 20000 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 64,192 electrons; unity gain is around ISO 320.