Sony a9 II vs Sony a900: read noise comparison

The Sony a9 II (ILCE-9M2) was measured at 37 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 1.80 DN, or 10.1 electrons at the sensor. A second gain (dual gain) kicks in at ISO 640, cutting input-referred read noise by about 1.8 stop. From ISO 5000 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 51200 don't change analog gain (digital push). Full well at base ISO is about 89,315 electrons; unity gain is around ISO 560.

The Sony a900 (DSLR-A900) was measured at 19 ISO settings from ISO 100 to ISO 6400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (200) read noise is 1.44 DN, or 6.6 electrons at the sensor. From ISO 250 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 3200 don't change analog gain (digital push). Full well at base ISO is about 74,744 electrons; unity gain is around ISO 920.