For anybody who has seen this lens... Does the lens get bigger when it zooms like say the Canon 28-70/2.8L ? There are advantages and disadvantages for it doing so. The advantage would be that the lens hood can be optimum at all focal lengths because it zooms out to 28mm making the hood more shallow. This I believe is particularly feasible to do on a mid-range zoom like this. The disadvantage of course would be weather sealing. From the photo it looks like the Nikon is fixed length - is that right?