Pentax Q vs Pentax Q7: read noise comparison

Input-referred read noise at base ISO: Pentax Q 2.1 e⁻ (ISO 125), Pentax Q7 3.2 e⁻ (ISO 100).

Pentax Q

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 Q7

The Pentax Q7 was measured at 22 ISO settings from ISO 100 to ISO 12800. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 1.27 DN, or 3.2 electrons at the sensor. From ISO 2000 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 10,402 electrons; unity gain is around ISO 250.

Pentax Q vs Pentax Q7 read noise table

ISO	Pentax Q	Pentax Q7
100	–	1.266
125	1.042	1.505
160	1.240	1.803
200	1.434	2.173
250	1.647	2.585
320	1.945	3.074
400	2.362	3.655
500	2.828	4.532
640	3.411	5.352
800	4.112	6.409
1000	5.098	7.516
1250	6.320	8.877
1600	7.835	10.629
2000	9.646	12.467
2500	11.632	15.889
3200	14.420	19.427
4000	18.126	23.752
5000	22.627	29.243
6400	30.065	35.753
8000	–	44.632
10000	–	57.680
12800	–	75.061

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