I suppose piers can be too massive, too. If a pier is much heavier than the load it carries then it will efficiently shield the latter from ground vibrations, but any vibrations generated in the mount (or wind grabbing hold of the scope) will reflect right back. It will then be entirely up to the damping capabilities of the mount-scope combo to kill them. I don't think mounts with scopes and counter-weights attached are very good at that.
I reckon the best pier would be:
- statically rigid, i.e. not flex with shifting static loads
- matched to the load in mass, so it can eagerly take up vibrations produced by the load, instead of reflecting them
- turn the received vibrations into heat as quickly as possible, transferring as little as possible back to the load
- isolate the load from ground vibrations
Number 1 seems to be what most people go for. Here bigger (heavier) is better.
Number 4 can be achieved with large mass and/or soft, absorbent suspension, which conflicts with 2 and 1, respectively. Therefore I think 4 is best kept off the pier and left to a very massive base.
Number 2 is probably the least intuitive to grasp. Matching a pier to the load is not easily done without experimentation. A super-massive pier will reflect vibrations coming from the top just as badly as a light-weight insert ("rat cage").
Number 3 is hard, vibration absorption is not easily achieved without violating number 1, rigidity. Spoiling the modes of the pier by welding on ribs etc is a bit of a cheat, but effective if it makes the pier oscillate at a variety of frequencies each at a lower amplitude. It also seems obvious that the pier should be dead at the resonant frequencies of the mount/scope/counter-weights contraption. How does one determine those? The often cited lead shot fill sounds like a good broadband dampener, and the large mass still wouldn't lead to reflections at the pier head since the lead shot is only loosely coupled to the pier. All energy not dissipated here will go right back into the load, the super-massive base will mostly reflect it.
I would conclude that it is impossible to design and build a good universal pier. Too much depends on the intended load and its dynamic properties. Some things should be avoided for sure, though, such as guitar-string piers (unspoilt metal tubes), super-massive piers and rat cages.
Just my 2 cents…
Cheers
Steffen.