On vacation in France, a private waterfall at our disposal. A perfect chance to try my recently purchased tripod to see if I can create some of those silky water shots.
Sat there for an hour playing with settings thinking I was great. Checked them later and they where pretty much all blurred.
Two mins googling and a link with disabling image stabilisation on the lens. Bingo. On the Tamron its actually VC (I forget the acronym). Tried a couple of test shots and it appears problem solved.
Back to the waterfall tomorrow afternoon.
I also found that VC doesn't actually work in the timed (10 seconds) shot mode. But it does seem to make a difference when the d30 takes the picture. So turn it off.
Not sure what other lens do this. I'll hopefully find out soon when I buy my bosses 'L's.