Sony RX100 III read noise vs ISO

The Sony RX100 III (DSC-RX100M3) was measured at 23 ISO settings from ISO 80 to ISO 12800. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (125) read noise is 3.58 DN, or 2.7 electrons at the sensor. From ISO 1000 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 5000 don't change analog gain (digital push). Full well at base ISO is about 11,621 electrons; unity gain is around ISO 90.