TREN
Pentax K-r read noise vs ISO
The Pentax K-r was measured at 9 ISO settings from ISO 100 to ISO 25600. Values were derived by Bill Claff from DxOMark lab data.
At base ISO (100) read noise is 0.90 DN. From ISO 12800 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise.
Pentax K-r read noise table
| ISO | Read noise (DN) | log₂ |
|---|---|---|
| 100 | 0.895 | -0.16 |
| 200 | 1.474 | 0.56 |
| 400 | 2.713 | 1.44 |
| 800 | 4.377 | 2.13 |
| 1600 | 10.056 | 3.33 |
| 3200 | 21.112 | 4.40 |
| 6400 | 32.447 | 5.02 |
| 12800 | 49.867 | 5.64 |
| 25600 | 128.890 | 7.01 |