Canon EOS 60Da vs Canon EOS 650D: read noise comparison

The Canon EOS 60Da was measured at 20 ISO settings from ISO 100 to ISO 12800. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 5.98 DN, or 14.2 electrons at the sensor. From ISO 2500 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 6400 don't change analog gain (digital push). Full well at base ISO is about 33,926 electrons; unity gain is around ISO 240.

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.