Canon PowerShot G3 X vs Canon PowerShot G5: read noise comparison

The Canon PowerShot G3 X was measured at 8 ISO settings from ISO 125 to ISO 12800. Values were derived by Bill Claff from DxOMark lab data.

At base ISO (125) read noise is 4.69 DN. From ISO 1600 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise.

The Canon PowerShot G5 was measured at 4 ISO settings from ISO 50 to ISO 400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (50) read noise is 3.05 DN, or 6.1 electrons at the sensor. From ISO 100 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 7,951 electrons; unity gain is around ISO 100.