Originally posted by jslifoaw Also, IBIS had one key disadvantage prior to mirrorless - the optical viewfinder image is not stabilized.
I don't regard that as a disadvantage. I'd rather see what I should be compensating, compared to not knowing how much and how I'm shaking the camera.
A stabilised image may support better AF, but this could be solved by moving the AF unit as well. It is also not clear to me under which conditions a stabilised image on the AF sensor would lead to better results.
Originally posted by jslifoaw You can tell IBIS is likely to be less effective at long focal lengths - in live view, you can hear the sensor bouncing around a lot.
The fact that the compensation range is exceed more often does not imply that the stabilisation is less effective (within the supported range).
Both lens-based and sensor-based stabilisation systems will reach their limits at some point; perhaps a lens-based solution allows more acceleration with less effort, but it just appears to be a question of how much effort to put into a sensor-based solution.