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Pentax 645Z vs Pentax K-01: read noise comparison

Pentax 645Z

The Pentax 645Z was measured at 34 ISO settings from ISO 100 to ISO 204800. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 1.19 DN, or 3.5 electrons at the sensor. From ISO 640 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 2500 don't change analog gain (digital push). Full well at base ISO is about 48,430 electrons; unity gain is around ISO 290.

Pentax K-01DxO

The Pentax K-01 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 0.70 DN. From ISO 800 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise.

Pentax 645Z vs Pentax K-01 read noise table

ISOPentax 645ZPentax K-01
1001.1890.697
1251.474–
1601.670–
2002.0991.028
2502.585–
3203.010–
4003.7581.705
5004.691–
6405.426–
8006.8212.868
10008.574–
12509.987–
160012.5535.278
200016.336–
250019.427–
320019.97313.833
400025.992–
500031.125–
640038.58627.474
800050.213–
1000059.714–
1280059.71458.081
1600077.708–
2000092.411–
25600119.428119.428
32000154.343–
40000184.823–
51200213.783–
64000276.282–
80000328.557–
102400424.612–
128000548.748–
160000652.575–
204800837.532–

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Data: Photons to Photos · © William J. Claff