Apple iPhone XS Max read noise vs ISO

The Apple iPhone XS Max was measured at 19 ISO settings from ISO 25 to ISO 2000. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (25) read noise is 1.88 DN, or 4.7 electrons at the sensor. From ISO 125 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 200 don't change analog gain (digital push). Full well at base ISO is about 8,980 electrons; unity gain is around ISO 60.