This is the method that we measure the dark current of a camera.
Here is as an example,
1. Capture a dark1 with 1s exopsure, gain 0 at -5C.
2. Capture a dark2 with 201s exopsure, gain 0 at -5C.
3. Calculate the Average ADU difference of this two image.
Assume the dark1: Average ADU 639
dark2: Average ADU 647
We can see in 100 second the ADU increases 8ADU, and when gain=0, 1 ADU=3.5e,
then we need to convert the ADU to the number of electrons,
As ASI183 is 12bit, the image it outputs is 16bit fit file, it has been convert to 16bit, so we have to convert it back,
3.5e/2^4=0.21875e,
0.21875 x 8=1.75e, then we will get 1.75e/200sec=0.0875e
The data is not precise, just want to show the methods.