TREN
Canon PowerShot G1 X Mark III read noise vs ISO
The Canon PowerShot G1 X Mark III was measured at 25 ISO settings from ISO 100 to ISO 25600. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.
At base ISO (100) read noise is 3.10 DN, or 5.4 electrons at the sensor. From ISO 5000 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 27,947 electrons; unity gain is around ISO 180.
Canon PowerShot G1 X Mark III read noise table
| ISO | Read noise (DN) | log₂ |
|---|---|---|
| 100 | 3.095 | 1.63 |
| 125 | 4.056 | 2.02 |
| 160 | 3.458 | 1.79 |
| 200 | 4.317 | 2.11 |
| 250 | 5.579 | 2.48 |
| 320 | 5.657 | 2.50 |
| 400 | 7.062 | 2.82 |
| 500 | 9.126 | 3.19 |
| 640 | 10.411 | 3.38 |
| 800 | 12.906 | 3.69 |
| 1000 | 16.223 | 4.02 |
| 1250 | 18.252 | 4.19 |
| 1600 | 23.264 | 4.54 |
| 2000 | 29.243 | 4.87 |
| 2500 | 32.447 | 5.02 |
| 3200 | 41.355 | 5.37 |
| 4000 | 51.984 | 5.70 |
| 5000 | 54.948 | 5.78 |
| 6400 | 70.035 | 6.13 |
| 8000 | 88.035 | 6.46 |
| 10000 | 110.661 | 6.79 |
| 12800 | 140.070 | 7.13 |
| 16000 | 171.255 | 7.42 |
| 20000 | ▼ 207.937 | 7.70 |
| 25600 | ▼ 250.732 | 7.97 |