Canon EOS R vs Canon EOS R1: read noise comparison

The Canon EOS R was measured at 27 ISO settings from ISO 100 to ISO 40000. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 2.73 DN, or 11.4 electrons at the sensor. From ISO 5000 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 66,292 electrons; unity gain is around ISO 420.

The Canon EOS R1 was measured at 34 ISO settings from ISO 50 to ISO 409600. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (200) read noise is 1.96 DN, or 6.9 electrons at the sensor. A second gain (dual gain) kicks in at ISO 1600, cutting input-referred read noise by about 1.5 stop. From ISO 3200 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 55,647 electrons; unity gain is around ISO 700.