Sony a700 vs Sony a77: read noise comparison

Input-referred read noise at base ISO: Sony a700 6.3 e⁻ (ISO 200), Sony a77 4 e⁻ (ISO 100).

Sony a700

The Sony a700 (DSLR-A700) was measured at 19 ISO settings from ISO 100 to ISO 6400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (200) read noise is 1.28 DN, or 6.3 electrons at the sensor. From ISO 250 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 3200 don't change analog gain (digital push). Full well at base ISO is about 19,384 electrons; unity gain is around ISO 980.

Sony a77

The Sony a77 (SLT-A77V) was measured at 26 ISO settings from ISO 50 to ISO 16000. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 3.39 DN, or 4 electrons at the sensor. From ISO 250 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 5000 don't change analog gain (digital push). Full well at base ISO is about 18,921 electrons; unity gain is around ISO 120.

Sony a700 vs Sony a77 read noise table

ISO	Sony a700	Sony a77
50	–	2.949
64	–	3.411
80	–	4.000
100	1.021	3.387
125	1.338	3.918
160	1.495	4.757
200	1.283	5.657
250	1.505	6.774
320	1.840	8.225
400	2.329	9.918
500	2.713	12.210
640	3.605	15.032
800	4.317	18.507
1000	5.169	22.943
1250	6.821	29.651
1600	8.815	37.271
2000	10.196	46.851
2500	13.269	58.081
3200	17.030	74.028
4000	20.252	93.054
5000	26.355	115.360
6400	33.359	112.206
8000	–	144.007
10000	–	181.019
12800	–	227.544
16000	–	286.026

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