Nikon D850 (ES) vs Nikon Df: read noise comparison

The Nikon D850 (ES) was measured at 30 ISO settings from ISO 32 to ISO 25600. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (64) read noise is 1.16 DN, or 4.3 electrons at the sensor. A second gain (dual gain) kicks in at ISO 400, cutting input-referred read noise by about 1.3 stop. From ISO 2500 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 59,127 electrons; unity gain is around ISO 230.

The Nikon Df was measured at 31 ISO settings from ISO 50 to ISO 204800. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 2.08 DN, or 15.7 electrons at the sensor. From ISO 10000 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 123,451 electrons; unity gain is around ISO 750.