I have been using a Bogen Ball Head for a few years. I has the squeeze head
that pivots in all directions. One advantage it has is that you can track a
flying bird which you can't do with the others. A disadvantage mentioned
previously is that when used with a group of birders, most don't know how to
use it. Some try to physically move the head which doesn't work.

Hugh Jennings
Bellevue, WA
hughbirder at aol.com