FujiFilm X-S1 vs FujiFilm X-T1: read noise comparison

The FujiFilm X-S1 was measured at 14 ISO settings from ISO 100 to ISO 3200. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 1.69 DN, or 3.4 electrons at the sensor. From ISO 320 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 7,773 electrons; unity gain is around ISO 200.

The FujiFilm X-T1 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 1.88 DN, or 3.8 electrons at the sensor. From ISO 320 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 1600 don't change analog gain (digital push). Full well at base ISO is about 31,158 electrons; unity gain is around ISO 410.