TREN
Canon EOS 1D X Mark II read noise vs ISO
The Canon EOS 1D X Mark II was measured at 31 ISO settings from ISO 100 to ISO 409600. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.
At base ISO (100) read noise is 2.22 DN, or 15.1 electrons at the sensor. From ISO 5000 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 51200 don't change analog gain (digital push). Full well at base ISO is about 108,359 electrons; unity gain is around ISO 680.
Canon EOS 1D X Mark II read noise table
| ISO | Read noise (DN) | log₂ |
|---|---|---|
| 100 | 2.219 | 1.15 |
| 125 | 2.567 | 1.36 |
| 160 | 2.071 | 1.05 |
| 200 | 2.362 | 1.24 |
| 250 | 2.828 | 1.50 |
| 320 | 2.412 | 1.27 |
| 400 | 2.848 | 1.51 |
| 500 | 3.434 | 1.78 |
| 640 | 3.138 | 1.65 |
| 800 | 3.864 | 1.95 |
| 1000 | 4.659 | 2.22 |
| 1250 | 4.790 | 2.26 |
| 1600 | 5.816 | 2.54 |
| 2000 | 7.311 | 2.87 |
| 2500 | 7.621 | 2.93 |
| 3200 | 9.514 | 3.25 |
| 4000 | 11.632 | 3.54 |
| 5000 | 13.086 | 3.71 |
| 6400 | 16.111 | 4.01 |
| 8000 | 20.252 | 4.34 |
| 10000 | 25.457 | 4.67 |
| 12800 | 32.000 | 5.00 |
| 16000 | 40.224 | 5.33 |
| 20000 | 50.914 | 5.67 |
| 25600 | 63.119 | 5.98 |
| 32000 | 79.341 | 6.31 |
| 40000 | 100.427 | 6.65 |
| 51200 | 123.640 | 6.95 |
| 102400 | ▼ 216.767 | 7.76 |
| 204800 | ▼ 349.706 | 8.45 |
| 409600 | ▼ 617.374 | 9.27 |