Focus adjusting apparatus of zoom lens

摘要

A focus adjusting apparatus in a zoom lens in which a position of a zooming optical system in a zoom lens barrel is varied in an optical axis direction in accordance with an axial position of a rotatable cam ring. The apparatus includes a back focus adjusting mechanism for adjusting the axial position of the cam ring, an axially movable member which is movable together with the cam ring in the optical axis direction in accordance with the axial movement of the cam ring upon back focus adjustment, and a detecting mechanism provided between the axially movable member and the cam ring for detecting an angular position of the cam ring.