Pentax K-1 vs Pentax K-1 II: read noise comparison

Input-referred read noise at base ISO: Pentax K-1 3.1 e⁻ (ISO 100), Pentax K-1 II 3.3 e⁻ (ISO 100).

Pentax K-1

The Pentax K-1 was measured at 30 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 1.20 DN, or 3.1 electrons at the sensor. From ISO 320 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 51200 don't change analog gain (digital push). Full well at base ISO is about 41,653 electrons; unity gain is around ISO 250.

Pentax K-1 II

The Pentax K-1 II was measured at 40 ISO settings from ISO 100 to ISO 819200. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 1.11 DN, or 3.3 electrons at the sensor. From ISO 160000 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 204800 don't change analog gain (digital push). Full well at base ISO is about 48,634 electrons; unity gain is around ISO 300.

Pentax K-1 vs Pentax K-1 II read noise table

ISO	Pentax K-1	Pentax K-1 II
100	1.197	1.110
125	1.444	1.357
160	1.659	1.548
200	2.042	1.919
250	2.532	2.378
320	2.928	2.751
400	3.605	3.387
500	4.595	4.199
640	5.352	2.412
800	6.727	2.949
1000	8.634	3.864
1250	10.196	4.287
1600	13.086	5.278
2000	17.630	7.210
2500	19.973	9.000
3200	25.992	10.928
4000	34.060	15.032
5000	40.224	16.795
6400	51.984	22.785
8000	68.594	33.128
10000	79.341	34.776
12800	103.968	49.180
16000	138.141	72.505
20000	158.683	73.009
25600	206.500	101.829
32000	266.871	150.123
40000	315.173	148.056
51200	404.501	209.383
64000	–	321.795
80000	–	292.036
102400	809.002	418.766
128000	–	634.730
160000	–	600.491
204800	1,606.828	891.444
256000	–	873.098
320000	–	955.426
409600	–	1,260.692
512000	–	1,595.729
640000	–	1,937.526
819200	–	2,256.702

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