[Shiraz (Ray)]

M&T

The chip has variable (inverse) gain that is controlled by a "true" gain number that sets the on-board conversion ratio (a higher gain number gives more ADU per electron). The translation between the gain number and the (inverse) gain is provided on the website charts - 200 is 20"db" gain although it is not specified "referred to what" - anyway, from the charts, a gain number of 200 corresponds to an (inverse) gain of ~0.6e/ADU with 12 bits output.

Then to make it a bit more complicated, the (hardware or the software?) changes the data from 12 bits to 16 bits by padding the bottom 4 bits with zeros. This is effectively an additional "true" gain of 16x, so the (inverse) gain in 16 bit ADU terms is ~0.6/16 e/ADU. ie gain 200 corresponds to an (inverse) gain of ~0.0375 e/ADU. At this setting, the well depth is only ~2000e, but the read noise has dropped to <1.5e.

I really hope this is some help - it was bad enough that everyone started calling the e/ADU conversion ratio a "gain". But then ZWO introduced a "true" gain number and also neglected to mention the hidden additional true gain of converting from 12 bits to 16 bits. Aaaargh.

if you are thinking about incorporating the 1600 into your acquisition software, perhaps be aware that it uses a streaming mode of USB3, which apparently puts heavy demands on the PC and doesn't tolerate faults. I am out of my depth on the details, but as far as I could tell, none of the standard acquisition packages worked properly when the 1600 was first released and the SGpro developers in particular had to modify some memory management? aspects of their package to make it work reliably.