I can't speak to your particular lens as I don't own it, but I have several that make that noise that loud, and all of my stabilized lenses make it to some degree. Shortly after taking the photo, the IS system shuts off to save power, and the click is the sound of it re-caging and centering itself (there's a mechanical pin or lever, depending on the module design, that holds the IS system centered when not in use). If you hold the shutter at the half position in between shots, the IS system should stay powered up (and eat your battery) and not have that noise. There's a felt recoil, even, in my 55-200 when this happens, and it's much louder than yours. But this varies model to model.
You can see it do it, by the way, if you look through the viewfinder (if it's not visible, try it after having about six shots of espresso). Zoom all the way in on a small target, and when you half press the shutter, the image in the viewfinder will stabilize, and you can watch the shakes re-appear a second or two after you release the shutter.
You can see it do it, by the way, if you look through the viewfinder (if it's not visible, try it after having about six shots of espresso). Zoom all the way in on a small target, and when you half press the shutter, the image in the viewfinder will stabilize, and you can watch the shakes re-appear a second or two after you release the shutter.
