Abstract: A zoom lens guide system employs air bearings to reduce mechanical shift of the zoom lens components, thus reducing measurement error. The air bearings provide greater stiffness, resulting in the reduction of mechanical shift. Orifice type or porous media air bearings can be used to provide a thin film between an external surface of the bearing and an inner surface of a barrel of the system, the bearing being mounted about a lens housing within the barrel. Guide pins include feed tubes connect the air bearings to an air supply while engaging a guide slot in the barrel and a cam slot in a zoom ring to effect selective axial motion of a lens housing.