Cam mechanism for a zoom lens

Described is a cam mechanism for a zoom lens (10) comprising a cam ring (31) having a plurality of arranged on its inner peripheral surface and / or the outer circumferential surface of cam grooves (CG1, CG2, CG3) having different reference profiles; having and a plurality of movable frames (35, 36, 37) along an optical axis (Z1) are guided linearly and a plurality of cam followers (CF1, CF2, CF3), with the cam grooves (CG1, CG2, CG3) are engaged, wherein each of the cam grooves (CG1, CG2, CG3) is provided with a Vario portion which is formed so that with rotation of the cam ring (31) the associated socket (35, 36, 37) along the optical axis (Z1) (between a wide-angle limit position W) and a telephoto limit position (T) is moved, and (a zoom boundary portion CG1-W, CG2 W, CG3-W), which is connected to one end of the zoom portion and is formed to a movement of the associated socket (35, 36, 37) along the optical axis (Z1) from the wide-angle limit position (W) and the telephoto limit position (T) is prevented, when the cam ring (31) within the zoom boundary portion (CG1-W, CG2 W, CG3-W) rotates.