Panasonic Lumix S5 II read noise vs ISO

The Panasonic Lumix S5 II (Lumix DC-S5M2) was measured at 37 ISO settings from ISO 50 to ISO 204800. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 1.18 DN, or 6.6 electrons at the sensor. A second gain (dual gain) kicks in at ISO 640, cutting input-referred read noise by about 1.7 stop. From ISO 20000 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 88,605 electrons; unity gain is around ISO 560.