TREN
Pentax K-30 read noise vs ISO
The Pentax K-30 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 0.59 DN, or 5.5 electrons at the sensor. From ISO 3200 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 38,618 electrons; unity gain is around ISO 940.
Pentax K-30 read noise table
| ISO | Read noise (DN) | log₂ |
|---|---|---|
| 100 | 0.586 | -0.77 |
| 125 | 0.678 | -0.56 |
| 160 | 0.758 | -0.40 |
| 200 | 0.908 | -0.14 |
| 250 | 1.072 | 0.10 |
| 320 | 1.240 | 0.31 |
| 400 | 1.505 | 0.59 |
| 500 | 1.892 | 0.92 |
| 640 | 2.204 | 1.14 |
| 800 | 2.751 | 1.46 |
| 1000 | 3.506 | 1.81 |
| 1250 | 4.084 | 2.03 |
| 1600 | ◆ 4.532 | 2.18 |
| 2000 | ◆ 5.776 | 2.53 |
| 2500 | ◆ 6.681 | 2.74 |
| 3200 | ◆ 7.160 | 2.84 |
| 4000 | ◆ 9.063 | 3.18 |
| 5000 | ◆ 11.236 | 3.49 |
| 6400 | ◆ 14.520 | 3.86 |
| 8000 | ◆ 18.636 | 4.22 |
| 10000 | ◆ 22.162 | 4.47 |
| 12800 | ◆ 28.443 | 4.83 |
| 16000 | ◆ 36.252 | 5.18 |
| 20000 | ◆ 43.713 | 5.45 |
| 25600 | ◆ 56.493 | 5.82 |