TREN
Leica M MONOCHROM (Typ 246) read noise vs ISO
The Leica M MONOCHROM (Typ 246) was measured at 18 ISO settings from ISO 320 to ISO 25600. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.
At base ISO (320) read noise is 0.97 DN, or 12.1 electrons at the sensor. From ISO 800 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 12800 don't change analog gain (digital push). Full well at base ISO is about 51,239 electrons; unity gain is around ISO 3970.
Leica M MONOCHROM (Typ 246) read noise table
| ISO | Read noise (DN) | log₂ |
|---|---|---|
| 320 | 0.973 | -0.04 |
| 400 | 1.021 | 0.03 |
| 500 | 1.133 | 0.18 |
| 640 | 1.357 | 0.44 |
| 800 | 1.404 | 0.49 |
| 1000 | 1.625 | 0.70 |
| 1250 | 2.071 | 1.05 |
| 1600 | 2.621 | 1.39 |
| 2000 | 3.340 | 1.74 |
| 2500 | 4.056 | 2.02 |
| 3200 | 5.134 | 2.36 |
| 4000 | 6.635 | 2.73 |
| 5000 | 8.515 | 3.09 |
| 6400 | 10.928 | 3.45 |
| 8000 | 13.642 | 3.77 |
| 10000 | 17.509 | 4.13 |
| 12800 | 21.857 | 4.45 |
| 25600 | ○ 46.527 | 5.54 |