Phase One IQ250 vs Phase One IQ4 150MP: read noise comparison

Input-referred read noise at base ISO: Phase One IQ250 2.5 e⁻ (ISO 200), Phase One IQ4 150MP 3.5 e⁻ (ISO 100).

Phase One IQ250

The Phase One IQ250 was measured at 7 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 5.86 DN, or 2.5 electrons at the sensor. From ISO 3200 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 27,950 electrons; unity gain is around ISO 90.

Phase One IQ4 150MP

The Phase One IQ4 150MP 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 4.17 DN, or 3.5 electrons at the sensor. From ISO 20000 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Full well at base ISO is about 54,029 electrons; unity gain is around ISO 80.

Phase One IQ250 vs Phase One IQ4 150MP read noise table

ISO	Phase One IQ250	Phase One IQ4 150MP
50	–	4.199
64	–	4.141
80	–	4.056
100	5.979	4.170
125	–	4.112
160	–	4.199
200	5.856	7.568
250	–	7.674
320	–	7.727
400	7.464	6.821
500	–	6.727
640	–	7.062
800	11.632	12.906
1000	–	13.642
1250	–	13.361
1600	19.973	25.813
2000	–	26.173
2500	–	25.634
3200	35.753	50.213
4000	–	49.867
5000	–	49.522
6400	65.345	95.670
8000	–	103.250
10000	–	97.006
12800	–	181.019
16000	–	177.294
20000	–	184.823
25600	–	372.217

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