FujiFilm X-H2S (ES) vs FujiFilm X-M1: read noise comparison

The FujiFilm X-H2S (ES) was measured at 20 ISO settings from ISO 160 to ISO 12800. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (160) read noise is 3.89 DN. A second gain (dual gain) kicks in at ISO 500, cutting input-referred read noise by about 1.2 stop. From ISO 2500 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise.

The FujiFilm X-M1 was measured at 16 ISO settings from ISO 200 to ISO 6400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (200) read noise is 0.67 DN, or 4.6 electrons at the sensor. From ISO 800 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 2500 don't change analog gain (digital push). Full well at base ISO is about 26,061 electrons; unity gain is around ISO 1350.