Pentax MX-1 vs Pentax Q7: read noise comparison

Input-referred read noise at base ISO: Pentax MX-1 4.2 e⁻ (ISO 100), Pentax Q7 3.2 e⁻ (ISO 100).

Pentax MX-1

The Pentax MX-1 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 1.84 DN, or 4.2 electrons at the sensor. From ISO 400 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 1000 don't change analog gain (digital push). Full well at base ISO is about 8,824 electrons; unity gain is around ISO 230.

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 MX-1 vs Pentax Q7 read noise table

ISO	Pentax MX-1	Pentax Q7
100	1.840	1.266
125	1.828	1.505
160	2.250	1.803
200	2.549	2.173
250	2.969	2.585
320	3.531	3.074
400	4.228	3.655
500	5.169	4.532
640	6.190	5.352
800	7.727	6.409
1000	9.063	7.516
1250	2.621	8.877
1600	3.918	10.629
2000	6.543	12.467
2500	17.148	15.889
3200	23.918	19.427
4000	31.341	23.752
5000	15.562	29.243
6400	24.761	35.753
8000	37.792	44.632
10000	26.173	57.680
12800	44.324	75.061

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