Sony a7R IV vs Sony a7R VI: read noise comparison

The Sony a7R IV (ILCE-7RM4) was measured at 34 ISO settings from ISO 50 to ISO 102400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 1.35 DN, or 2.9 electrons at the sensor. A second gain (dual gain) kicks in at ISO 320, cutting input-referred read noise by about 1.1 stop. From ISO 400 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 12800 don't change analog gain (digital push). Full well at base ISO is about 34,452 electrons; unity gain is around ISO 220.

The Sony a7R VI (ILCE-7RM6) was measured at 34 ISO settings from ISO 50 to ISO 102400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 0.66 DN, or 1.5 electrons at the sensor. From ISO 16000 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 32000 don't change analog gain (digital push). Full well at base ISO is about 35,938 electrons; unity gain is around ISO 230.