[gars]

Originally Posted by !MiKrofT

That's cause it's not Ring USM. They use Micro USM. A cheaper, slower, noisier alternative.

http://forums.dpreview.com/forums/re...ssage=15260787

Yes, the Micro USM is noisy, but after it focuses, you can definitely hear the buzz of the IS. I love how well the IS works on it though - especially if you're shooting at 300mm - the picture just stabilizes in the viewfinder.

It's definitely a great lens!