TREN
Canon EOS 5D Mark III read noise vs ISO
The Canon EOS 5D Mark III was measured at 28 ISO settings from ISO 50 to ISO 102400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.
At base ISO (100) read noise is 6.45 DN, or 27.7 electrons at the sensor. From ISO 8000 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 25600 don't change analog gain (digital push). Full well at base ISO is about 61,512 electrons; unity gain is around ISO 430.
Canon EOS 5D Mark III read noise table
| ISO | Read noise (DN) | log₂ |
|---|---|---|
| 50 | ○ 6.498 | 2.70 |
| 100 | 6.453 | 2.69 |
| 125 | 8.056 | 3.01 |
| 160 | 5.464 | 2.45 |
| 200 | 6.727 | 2.75 |
| 250 | 8.456 | 3.08 |
| 320 | 5.979 | 2.58 |
| 400 | 7.311 | 2.87 |
| 500 | 9.318 | 3.22 |
| 640 | 6.774 | 2.76 |
| 800 | 8.574 | 3.10 |
| 1000 | 10.778 | 3.43 |
| 1250 | 9.318 | 3.22 |
| 1600 | 11.632 | 3.54 |
| 2000 | 14.420 | 3.85 |
| 2500 | 14.320 | 3.84 |
| 3200 | 18.126 | 4.18 |
| 4000 | 22.471 | 4.49 |
| 5000 | 27.096 | 4.76 |
| 6400 | 34.297 | 5.10 |
| 8000 | 42.518 | 5.41 |
| 10000 | 47.505 | 5.57 |
| 12800 | 59.714 | 5.90 |
| 16000 | 74.028 | 6.21 |
| 20000 | 92.411 | 6.53 |
| 25600 | 114.563 | 6.84 |
| 51200 | ○ 218.275 | 7.77 |
| 102400 | ▼ 380.038 | 8.57 |