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

Input-referred read noise at base ISO: Canon EOS 1D Mark III 21.3 e⁻ (ISO 100), Canon EOS 1D Mark IV 16.9 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 Mark IV

The Canon EOS 1D Mark IV was measured at 26 ISO settings from ISO 50 to ISO 102400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (100) read noise is 5.03 DN, or 16.9 electrons at the sensor. From ISO 5000 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 12800 don't change analog gain (digital push). Full well at base ISO is about 48,272 electrons; unity gain is around ISO 340.

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

ISO	Canon EOS 1D Mark III	Canon EOS 1D Mark IV
50	4.790	5.063
100	4.857	5.028
125	5.776	6.233
160	6.916	4.287
200	5.098	5.205
250	6.190	6.498
320	7.516	4.959
400	5.979	6.021
500	7.413	7.568
640	9.126	6.233
800	8.574	7.516
1000	10.483	9.580
1250	12.996	9.063
1600	13.833	11.392
2000	17.630	14.420
2500	21.556	15.348
3200	26.538	19.427
4000	–	23.752
5000	–	25.107
6400	54.948	32.000
8000	–	39.397
10000	–	47.835
12800	–	56.886
25600	–	110.661
51200	–	218.275
102400	–	333.144

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