TREN
Pentax Q read noise vs ISO
The Pentax Q was measured at 18 ISO settings from ISO 125 to ISO 6400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.
At base ISO (125) read noise is 1.04 DN, or 2.1 electrons at the sensor. From ISO 800 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 8,427 electrons; unity gain is around ISO 260.
Pentax Q read noise table
| ISO | Read noise (DN) | log₂ |
|---|---|---|
| 125 | ▼ 1.042 | 0.06 |
| 160 | ▼ 1.240 | 0.31 |
| 200 | ▼ 1.434 | 0.52 |
| 250 | ▼ 1.647 | 0.72 |
| 320 | ▼ 1.945 | 0.96 |
| 400 | ▼ 2.362 | 1.24 |
| 500 | ▼ 2.828 | 1.50 |
| 640 | ▼ 3.411 | 1.77 |
| 800 | ▼ 4.112 | 2.04 |
| 1000 | ▼ 5.098 | 2.35 |
| 1250 | ▼ 6.320 | 2.66 |
| 1600 | ▼ 7.835 | 2.97 |
| 2000 | ▼ 9.646 | 3.27 |
| 2500 | ▼ 11.632 | 3.54 |
| 3200 | ▼ 14.420 | 3.85 |
| 4000 | ▼ 18.126 | 4.18 |
| 5000 | ▼ 22.627 | 4.50 |
| 6400 | ▼ 30.065 | 4.91 |