TREN
Zeiss ZX1 read noise vs ISO
The Zeiss ZX1 was measured at 29 ISO settings from ISO 80 to ISO 51200. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.
At base ISO (100) read noise is 2.73 DN, or 7.4 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 6400 don't change analog gain (digital push). Full well at base ISO is about 41,603 electrons; unity gain is around ISO 270.
Zeiss ZX1 read noise table
| ISO | Read noise (DN) | log₂ |
|---|---|---|
| 80 | ○ 3.681 | 1.88 |
| 100 | 2.732 | 1.45 |
| 125 | 3.387 | 1.76 |
| 160 | 4.377 | 2.13 |
| 200 | 4.659 | 2.22 |
| 250 | 5.856 | 2.55 |
| 320 | 7.516 | 2.91 |
| 400 | 11.959 | 3.58 |
| 500 | 14.825 | 3.89 |
| 640 | 19.293 | 4.27 |
| 800 | 25.107 | 4.65 |
| 1000 | 31.341 | 4.97 |
| 1250 | 39.124 | 5.29 |
| 1600 | 37.531 | 5.23 |
| 2000 | 46.851 | 5.55 |
| 2500 | 58.485 | 5.87 |
| 3200 | 75.584 | 6.24 |
| 4000 | 94.353 | 6.56 |
| 5000 | 117.784 | 6.88 |
| 6400 | 150.123 | 7.23 |
| 8000 | ○ 188.706 | 7.56 |
| 10000 | ○ 235.568 | 7.88 |
| 12800 | ○ 294.067 | 8.20 |
| 16000 | ○ 364.557 | 8.51 |
| 20000 | ○ 455.087 | 8.83 |
| 25600 | ○ 576.030 | 9.17 |
| 32000 | ○ 704.277 | 9.46 |
| 40000 | ○ 843.357 | 9.72 |
| 51200 | ○ 1,016.927 | 9.99 |