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Olympus System OM-1 Mark II (HR) vs Olympus System OM-3 Astro: read noise comparison

Input-referred read noise at base ISO: Olympus System OM-1 Mark II (HR) 7.8 e⁻ (ISO 200), Olympus System OM-3 Astro 3.9 e⁻ (ISO 200).

Olympus System OM-1 Mark II (HR)

The Olympus System OM-1 Mark II (HR) was measured at 12 ISO settings from ISO 80 to ISO 1600. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (200) read noise is 1.97 DN, or 7.8 electrons at the sensor. From ISO 1000 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 60,830 electrons; unity gain is around ISO 790.

Olympus System OM-3 Astro

The Olympus System OM-3 Astro was measured at 30 ISO settings from ISO 80 to ISO 102400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (200) read noise is 0.76 DN, or 3.9 electrons at the sensor. From ISO 16000 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 19,956 electrons; unity gain is around ISO 1040.

Olympus System OM-1 Mark II (HR) vs Olympus System OM-3 Astro read noise table

ISO	Olympus System OM-1 Mark II (HR)	Olympus System OM-3 Astro
80	2.346	0.973
100	2.028	0.807
200	1.972	0.758
250	2.282	0.871
320	2.585	1.035
400	3.010	1.214
500	3.434	1.444
640	4.084	1.670
800	4.823	2.085
1000	3.945	1.682
1250	4.891	2.014
1600	5.856	2.479
2000	–	3.053
2500	–	3.655
3200	–	4.500
4000	–	5.426
5000	–	6.774
6400	–	8.282
8000	–	10.126
10000	–	12.996
12800	–	16.111
16000	–	15.348
20000	–	19.698
25600	–	24.933
32000	–	30.065
40000	–	38.854
51200	–	48.503
64000	–	60.969
80000	–	76.639
102400	–	94.353

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