TREN
Canon PowerShot G1 X read noise vs ISO
The Canon PowerShot G1 X was measured at 22 ISO settings from ISO 100 to ISO 12800. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.
At base ISO (100) read noise is 12.64 DN, or 18.5 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 23,197 electrons; unity gain is around ISO 150.
Canon PowerShot G1 X read noise table
| ISO | Read noise (DN) | log₂ |
|---|---|---|
| 100 | 12.641 | 3.66 |
| 125 | 16.000 | 4.00 |
| 160 | 19.835 | 4.31 |
| 200 | 12.467 | 3.64 |
| 250 | 15.455 | 3.95 |
| 320 | 19.973 | 4.32 |
| 400 | 14.723 | 3.88 |
| 500 | 18.507 | 4.21 |
| 640 | 23.588 | 4.56 |
| 800 | 20.112 | 4.33 |
| 1000 | 25.634 | 4.68 |
| 1250 | 32.900 | 5.04 |
| 1600 | 30.910 | 4.95 |
| 2000 | 39.124 | 5.29 |
| 2500 | 49.180 | 5.62 |
| 3200 | 58.892 | 5.88 |
| 4000 | 74.543 | 6.22 |
| 5000 | 93.701 | 6.55 |
| 6400 | 117.784 | 6.88 |
| 8000 | ▼ 144.007 | 7.17 |
| 10000 | ▼ 178.527 | 7.48 |
| 12800 | ▼ 202.251 | 7.66 |