Tom has great advice, but he doesn't comment on Vanguard Ball head quality at all. He seems to cover all the other brands.
Can anyone with the Vanguard B-300 comment on movement while tightening, or does the tip of a long lens move during a 1/2 second exposure? Is this a ball head that a professional could use and be happy with? Like Tom mentions, I've already bought one ball head that doesn't get the job done and I really only want to buy one more.