Foot for optical or photographic supports

A foot for optical or photographic supports, including a telescopic rod having several telescopic members and, for each pair of adjacent telescopic members, an expanding stop mechanism mounted on one telescopic member of the pair and acting on the other telescopic member of the pair in order to block their relative sliding motion in a first direction of two directions of relative sliding motion and to release the relative sliding motion in the other of the two directions, and also means for the release on command of the stop mechanism for releasing on command the relative sliding motion in the first direction, the stop mechanism including a radially expandable ring and an expander body for the ring for pressing the elements of the ring radially against an inner shell of the other telescopic member as a consequence of a relative movement between the ring and the expander body, the foot wherein the ring comprises a plurality of barrel rollers having an outer shell with a curvature coinciding substantially with the curvature of the inner shell of the other telescopic member.