Sony a99 vs Sony DSC-R1: read noise comparison

Input-referred read noise at base ISO: Sony a99 4.3 e⁻ (ISO 100), Sony DSC-R1 10.5 e⁻ (ISO 200).

Sony a99

The Sony a99 (SLT-A99V) was measured at 28 ISO settings from ISO 50 to ISO 25600. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 1.31 DN, or 4.3 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 6400 don't change analog gain (digital push). Full well at base ISO is about 51,834 electrons; unity gain is around ISO 330.

Sony DSC-R1

The Sony DSC-R1 was measured at 5 ISO settings from ISO 200 to ISO 3200. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (200) read noise is 12.91 DN, or 10.5 electrons at the sensor. From ISO 200 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 12,866 electrons; unity gain is around ISO 160.

Sony a99 vs Sony DSC-R1 read noise table

ISO	Sony a99	Sony DSC-R1
50	1.141	–
64	1.301	–
80	1.495	–
100	1.310	–
125	1.495	–
160	1.729	–
200	2.042	12.906
250	2.428	–
320	2.868	–
400	3.458	26.173
500	4.228	–
640	5.205	–
800	6.453	49.522
1000	8.112	–
1250	10.126	–
1600	12.729	99.044
2000	16.000	–
2500	20.112	–
3200	25.457	192.672
4000	32.000	–
5000	40.504	–
6400	50.563	–
8000	63.558	–
10000	80.449	–
12800	101.125	–
16000	128.000	–
20000	162.017	–
25600	200.854	–

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