Phase One IQ3 100MP vs Phase One IQ3 80MP: read noise comparison

The Phase One IQ3 100MP was measured at 9 ISO settings from ISO 50 to ISO 12800. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 3.10 DN, or 2.3 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 3200 don't change analog gain (digital push). Full well at base ISO is about 48,513 electrons; unity gain is around ISO 80.

The Phase One IQ3 80MP was measured at 7 ISO settings from ISO 50 to ISO 3200. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (50) read noise is 20.25 DN. A second gain (dual gain) kicks in at ISO 1600, cutting input-referred read noise by about 1.5 stop. From ISO 1600 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise.