Nikon Coolpix P7800 vs Nikon D100: read noise comparison

The Nikon Coolpix P7800 was measured at 8 ISO settings from ISO 80 to ISO 6400. Values were derived by Bill Claff from DxOMark lab data.

At base ISO (80) read noise is 1.28 DN. From ISO 3200 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise.

The Nikon D100 was measured at 12 ISO settings from ISO 200 to ISO 6400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (200) read noise is 2.73 DN, or 16 electrons at the sensor. From ISO 400 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 1600 don't change analog gain (digital push). Full well at base ISO is about 23,964 electrons; unity gain is around ISO 1170.