seems the 0.4e- read noise is a canard - because you get that at ISO 409600 as per sensorgen... at which the full well is a measly 55e-
who uses ISO 409600?
all sensorgen numbers: if we assume (measured) ISO 1600 equivalent here are some numbers:
Olympus E-PL5 (Sony IMX109) - ISO 3200, measured ISO 1668, read noise 2.1e-, full well 1463e-, DR 9.4, QE 60%
Sony A6000 - ISO 3200, measured ISO 2510, read noise 2.5e-, full well 1064e-, DR 8.7, QE 61%
Sony A7S - ISO 3200, measured ISO 2627, read noise 4.1e-, full well 5453, DR 10.4, QE 65%
Canon 6D - ISO 3200, measured ISO 2400, read noise 2.3e-, full well 2481, DR 10.1, QE 47%
So the A7S is not "head and shoulders" above the 6D - it actually has almost double the read noise; but it also has double the full well.
It also looks to me that, if you stick with ISO 3200, the A6000 is actually a "better" deal than the A7S with its lower read noise. Of course the full well is only 20% so you'll get a lot of saturated stars.
It seems that at ISO below 12800, the 6D actually has lower read noise. And I fail to see the benefit of ultra-high ISO because the full well is very shallow at those gain levels..
Edited by orlyandico, 27 January 2015 - 04:19 AM.