The disclosed pivoting device is used with a frame structure that supports optical units, such as surgical microscopes and the like, for viewing a predetermined observation point, the frame structure being adjustable in height and in relation to three coordinate axes. The pivoting device carries the optical unit and permits adjustment of the unit about three axes of rotation to any desired position over a spherical surface. The pivoting device includes counterbalancing apparatus that adjusts synchronously with the movement of the optical unit. With this apparatus, it is easy to move the optical unit, and minor adjustments in the position of the optical unit do not require an adjustment of the frame structure. In addition, since the pivoting device's three primary axes of rotation all intersect at the observation point, focus of the optical unit relative to the observation point is not changed by such minor spatial adjustments of the unit.