FujiFilm X-T100 vs FujiFilm X-T20: read noise comparison

The FujiFilm X-T100 was measured at 19 ISO settings from ISO 200 to ISO 12800. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (200) read noise is 2.22 DN, or 2.7 electrons at the sensor. From ISO 640 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 18,751 electrons; unity gain is around ISO 240.

The FujiFilm X-T20 was measured at 22 ISO settings from ISO 100 to ISO 51200. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (200) read noise is 2.17 DN, or 3.4 electrons at the sensor. A second gain (dual gain) kicks in at ISO 800, cutting input-referred read noise by about 1.2 stop. From ISO 1600 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 25600 don't change analog gain (digital push). Full well at base ISO is about 24,261 electrons; unity gain is around ISO 320.