TREN
Canon EOS 1D Mark III read noise vs ISO
The Canon EOS 1D Mark III was measured at 18 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 4.86 DN, or 21.3 electrons at the sensor. From ISO 1600 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 67,078 electrons; unity gain is around ISO 440.
Canon EOS 1D Mark III read noise table
| ISO | Read noise (DN) | log₂ |
|---|---|---|
| 50 | ○ 4.790 | 2.26 |
| 100 | 4.857 | 2.28 |
| 125 | 5.776 | 2.53 |
| 160 | 6.916 | 2.79 |
| 200 | 5.098 | 2.35 |
| 250 | 6.190 | 2.63 |
| 320 | 7.516 | 2.91 |
| 400 | 5.979 | 2.58 |
| 500 | 7.413 | 2.89 |
| 640 | 9.126 | 3.19 |
| 800 | 8.574 | 3.10 |
| 1000 | 10.483 | 3.39 |
| 1250 | 12.996 | 3.70 |
| 1600 | 13.833 | 3.79 |
| 2000 | 17.630 | 4.14 |
| 2500 | 21.556 | 4.43 |
| 3200 | 26.538 | 4.73 |
| 6400 | ○ 54.948 | 5.78 |