I mean in nightscapes no one really is doing darks/flats and biases or rarely. These are fast exposure times, so dark current is not a factor, and is not relevant to many second exposures. But if the Canon 7D2 is so low in dark current then why is the DPR studio comparison tool show it to no less noisy than many other cameras? That's why we might be interested in dark current On a warm night, the dark current could even become the main source of image noise. Thus the dark current is a significant contributor to image noise. So you would be accumulating dark current at the same rate as photons from the background sky. Now if the sensor temperature is 20C then the dark current will also be around 0.1e/pix/sec even on the very low dark current Canon 7D2. The blue pixels will accumulate skyglow electrons much slower, at say 0.1e/pix/sec. If the pixel size is 4microns, the lens (or telescope) is F5.6, the sensor QE is 50% and you are imaging under a dark sky of 21.6 mags/square_arcsec then your green pixels will accumulate electrons from the background skyglow at a rate of approximately 0.2electrons/pixel/sec.
#Dark noise art full
Let's suppose you are doing full colour astro-imaging with a DSLR. Why are we interested in dark current? Here's why, by means of an example. What we are interested in here is the end result, the accumulated noise from various electronic components and this is where the DPR Studio review tool is handy. I am not sure why you are concentrating on dark current in the first place. All these cameras have incredibly low dark current.