TREN
Pentax K-5 read noise vs ISO
The Pentax K-5 was measured at 11 ISO settings from ISO 80 to ISO 51200. Values were derived by Bill Claff from DxOMark lab data.
At base ISO (80) read noise is 1.13 DN. From ISO 25600 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise.
Pentax K-5 read noise table
| ISO | Read noise (DN) | log₂ |
|---|---|---|
| 80 | 1.133 | 0.18 |
| 100 | 1.485 | 0.57 |
| 200 | 2.676 | 1.42 |
| 400 | 4.563 | 2.19 |
| 800 | 8.398 | 3.07 |
| 1600 | 13.929 | 3.80 |
| 3200 | 46.851 | 5.55 |
| 6400 | 93.701 | 6.55 |
| 12800 | 196.720 | 7.62 |
| 25600 | 349.706 | 8.45 |
| 51200 | 604.668 | 9.24 |