An optical assembly includes a light path and at least one optic to be
positioned in the path. A support arrangement supports the optic having a
foot arrangement including at least one foot that receives a direct
manipulation with the foot slidingly engaged against a support surface to
move the optic relative to the light path. Movement of the foot may move
the optic along a predetermined path. The foot defines a footprint for
engaging the support surface and receives the direct manipulation in a
way which changes the footprint on the support surface to move the optic
responsive to changes in the footprint. A movement arrangement may
selectively bias the foot against the support surface during a movement
mode, intended to permit movement of the foot against the support
surface, and in a locked mode, intended to lock the foot against the
support surface.