Quote Originally Posted by TheFlyingCamera View Post
I'm assuming you're already using a tripod. If not, that's the first step. Second, if you already are using a tripod, try a gimbal head for your long lens - the camera/lens combo will mount to the gimbal head via the lens' tripod mounting block, and the whole assembly will be mounted at more or less the balance point, instead of at one extreme, which will tend to induce vibration and motion.
Actually, the theory that the exact balance point will allow vibrations to resonate for a longer period, so most long lenses are designed with the tripod mount slightly in front of or behind the balance point.

More information here:

http://www.tripodhead.com/

http://www.the-digital-picture.com/r...II-Review.aspx