>>2594712First, it's important to remember that Canon's sensors are *not* of the isoless/iso-invariant variety, in explaining why- because that's why this isn't really an issue on other sensors anymore.
ISO 160 is your native, which means that ISO 100 is 'simulated', it's ISO 160 pulled down. Being non-isoless, any pushing/pulling has at least *some* degradation in IQ.