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you don't actually Have to expose lots of short subs with a 1600 - but you Can if you choose to, without losing SNR - simply because it has such low read noise..
This actually gives the 1600 higher dynamic range after stacking than any other affordable chip that I am aware of.
To put some numbers on it, compare two representative chips:
a CCD with 10e RN and 100,000e well depth
a CMOS with 2e RN and 10,000e well depth
the sky-limited sub length scales with the square of the RN, so the sky-limited subs with the CMOS will only need to be 1/25 as long as those from the CCD - ie, for a given exposure there will be 25x as many of them. Now, the maximum signal for a stack of N CCD subs will be N*100,000e and for 25*N CMOS subs will be N*25*10,000 - ie after stacking, the two systems will provide the same SNR, but the CMOS will give 2.5x the final dynamic range. Put another way, a star could 2.5 times a bright before saturation on the CMOS cf the CCD.
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