Originally posted by Matus 5/4
The zooms mentioned are about 2 pounds each. The body is under 3 pounds, so weight is less than 5 pounds. At 45 degrees, tripod legs form an equilateral tetrahedron, which can handle handle forces better than any other geometric structure! The problem is mechanical vibration that can be caused by the wind, tripod design, or distribution of weight on the tripod head. You're right that top heavy is not a good thing. What photographers generally do is install a hook under the center column and attach a sand bag or a bean bag with some heft. That will dampen or eliminate vibrations altogether. You want to bring the tripod weigh up to 5 or 6 pounds this way.
This may seem like a dumb idea if you've got to carry another 3 pounds, but if you're going to get camera shake, why bring a camera at all! Also, a bean bag or sand bag makes an excellent camera rest, with excellent vertical and horizontal stability, enough for slower than normal speeds (but not very slow speeds called for with small apertures).
Some photographers make it their mission in life to eliminate vibrations that rob images of their sharpness and will carry a 15 pound tripod (like my big boy Gitzo with Majestic geared head). Rock steady, rock on!