I got a 16-35 f4 L yesterday, and I noticed a slight buzzing noise it makes. With IS off it is extremely silent, however when you switch IS on it makes a slight buzzing noise after it locks focus.
Is this normal?
No other IS lens I own makes that little buzzing noise after I lock focus. Doesn't matter if I use it in low light or bright sunlight; it still makes that buzzing sound.

