Canon EOS 1D Mark III vs Canon EOS 1D X: read noise comparison

Input-referred read noise at base ISO: Canon EOS 1D Mark III 21.3 e⁻ (ISO 100), Canon EOS 1D X 30.7 e⁻ (ISO 100).

Canon EOS 1D Mark III

The Canon EOS 1D Mark III was measured at 18 ISO settings from ISO 50 to ISO 6400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 4.86 DN, or 21.3 electrons at the sensor. From ISO 1600 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 67,078 electrons; unity gain is around ISO 440.

Canon EOS 1D X

The Canon EOS 1D X was measured at 31 ISO settings from ISO 50 to ISO 204800. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 5.31 DN, or 30.7 electrons at the sensor. From ISO 10000 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 51200 don't change analog gain (digital push). Full well at base ISO is about 82,802 electrons; unity gain is around ISO 580.

Canon EOS 1D Mark III vs Canon EOS 1D X read noise table

ISO	Canon EOS 1D Mark III	Canon EOS 1D X
50	4.790	5.242
100	4.857	5.315
125	5.776	5.352
160	6.916	5.389
200	5.098	5.028
250	6.190	4.959
320	7.516	5.028
400	5.979	5.134
500	7.413	5.315
640	9.126	5.540
800	8.574	5.464
1000	10.483	5.696
1250	12.996	6.063
1600	13.833	6.453
2000	17.630	6.916
2500	21.556	7.890
3200	26.538	8.815
4000	–	11.632
5000	–	12.996
6400	54.948	15.242
8000	–	19.562
10000	–	22.471
12800	–	26.723
16000	–	34.535
20000	–	43.111
25600	–	53.817
32000	–	66.718
40000	–	83.865
51200	–	103.968
102400	–	198.088
204800	–	362.039

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