For this test, because it is a test about the dark current. If the exposure time is short, we usually think the dark current is not the main noise. the main noise should be read noise and other noise. That is why I suggest that use the 2 second to make the test.
But for bias field, usually, we want to use it to calibrate the read noise. So it should not a long exposured image. Also consider the fluctuations of the circuit, I suggest that you can use 0.1ms instead of 32μS to make the bias field. It should be better.
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