Acratech Ultimate Ballhead with Quick Release
Description (from B&H): The Acratech Ultimate Ballhead is the most efficient design ever created for combining low mass with incredible stopping power. Available with or without an installed Arca-type quick release clamp, it is an ideal head for those that do not require the progressive tension control of the heavier (and more expensive) Arca-Swiss B1. It can be combined with a Wimberley Sidekick to give exceptional gimbal-type control of all but the largest of 35mm & medium format supertelephoto lenses.
The innovative design of the Acratech gives the photographer full access to 25% of a sphere at any time, and it is entirely capable of providing support in any direction so long as your tripod legs are not overwhelmed. It may seem odd that such a small device would work well on a large tripod such as a 1500 series Gitzo, but in fact it does just that.
Occasionally it is necessary to reorient the controls of the Acratech to access a particular angle, because the clamp is mounted at a 45° angle to the ballhead. Thus, if one needs to point straight down on one shot and then five degrees backward on the next, one must reorient the clamp 180°. This is quickly mastered and not a detriment to ownership, as the benefits of traveling with such a lightweight design are realized every time it is carried.