TREN
Canon EOS 5D Mark II read noise vs ISO
The Canon EOS 5D Mark II was measured at 22 ISO settings from ISO 50 to ISO 25600. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.
At base ISO (100) read noise is 6.77 DN, or 27.1 electrons at the sensor. From ISO 1250 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 6400 don't change analog gain (digital push). Full well at base ISO is about 61,399 electrons; unity gain is around ISO 400.
Canon EOS 5D Mark II read noise table
| ISO | Read noise (DN) | log₂ |
|---|---|---|
| 50 | ○ 6.821 | 2.77 |
| 100 | 6.774 | 2.76 |
| 125 | 8.515 | 3.09 |
| 160 | 5.426 | 2.44 |
| 200 | 6.869 | 2.78 |
| 250 | 8.574 | 3.10 |
| 320 | 5.938 | 2.57 |
| 400 | 7.413 | 2.89 |
| 500 | 9.383 | 3.23 |
| 640 | 6.821 | 2.77 |
| 800 | 8.574 | 3.10 |
| 1000 | 11.004 | 3.46 |
| 1250 | 9.918 | 3.31 |
| 1600 | 12.381 | 3.63 |
| 2000 | 15.562 | 3.96 |
| 2500 | 19.562 | 4.29 |
| 3200 | 24.420 | 4.61 |
| 4000 | 30.910 | 4.95 |
| 5000 | 38.319 | 5.26 |
| 6400 | 49.867 | 5.64 |
| 12800 | ○ 97.006 | 6.60 |
| 25600 | ○ 194.012 | 7.60 |