Canon EOS 650D vs Canon EOS 6D Mark II: read noise comparison

The Canon EOS 650D was measured at 9 ISO settings from ISO 100 to ISO 25600. Values were derived by Bill Claff from DxOMark lab data.

At base ISO (100) read noise is 9.99 DN. Read noise keeps falling across the measured range, so the camera isn't fully ISO-invariant there.

The Canon EOS 6D Mark II was measured at 30 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 7.31 DN, or 36.5 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 40000 don't change analog gain (digital push). Full well at base ISO is about 79,343 electrons; unity gain is around ISO 500.