TREN
Nikon D3X read noise vs ISO
The Nikon D3X was measured at 20 ISO settings from ISO 50 to ISO 6400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.
At base ISO (100) read noise is 2.06 DN, or 5.9 electrons at the sensor. From ISO 200 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 46,773 electrons; unity gain is around ISO 280.
Nikon D3X read noise table
| ISO | Read noise (DN) | log₂ |
|---|---|---|
| 50 | ○ 2.056 | 1.04 |
| 64 | ○ 2.056 | 1.04 |
| 80 | ○ 2.056 | 1.04 |
| 100 | 2.056 | 1.04 |
| 125 | 2.770 | 1.47 |
| 160 | 3.458 | 1.79 |
| 200 | 2.828 | 1.50 |
| 250 | 3.555 | 1.83 |
| 320 | 4.724 | 2.24 |
| 400 | 5.979 | 2.58 |
| 500 | 7.111 | 2.83 |
| 640 | 8.877 | 3.15 |
| 800 | 11.236 | 3.49 |
| 1000 | 13.929 | 3.80 |
| 1250 | 17.509 | 4.13 |
| 1600 | 21.706 | 4.44 |
| 2000 | ○ 27.096 | 4.76 |
| 2500 | ○ 34.060 | 5.09 |
| 3200 | ○ 42.814 | 5.42 |
| 6400 | ○ 86.823 | 6.44 |