Patent ID: 7515355

Claim:
A compact zoom lens that has a multi-layer telescopic structure with four groups of lenses, or first to fourth lens groups, comprising a fixed barrel, a second-lens-group sliding frame, a first cam barrel, and a linearly movable barrel underlaying the fixed barrel one over another in this order, a second cam barrel overlaying the fixed barrel, the fixed barrel being formed with longitudinal guide grooves in which third-lens-group guide studs are fitted, the guide studs being implanted in and extending outward from a third-lens-group holding frame; the first cam barrel being provided with third-lens-group and fourth-lens-group guide cams, the third-lens-group guide studs being engaged with the third-lens-group guide cams while fourth-lens-group guide studs are engaged with the fourth-lens-group guide cams, and the first cam barrel having its end closer to an object formed with recesses that extend along the optical axis; the second-lens-group sliding frame having studs implanted therein and extending outward therefrom to cooperatively work with the second cam barrel, and also having second-lens-group studs implanted therein and extending inward therefrom; the linearly movable barrel being provided with apertures, longitudinal guide grooves, and second-lens-group guide cams, the third-lens-group guide studs being fitted in the apertures, the fourth-lens-group guide studs being fitted in the longitudinal guide grooves, the second-lens-group studs being engaged with the guide cams, and studs protruding outward being located ahead of the fixed barrel so as to guide a first-lens-group sliding frame; and the second cam barrel having its outer surface provided with first-lens-group guide cams and its inner surface formed with longitudinal guide grooves, first-lens-group sliding studs implanted in the first-lens-group sliding frame being engaged with the first-lens-group guide cams while the studs implanted in the second-lens-group sliding frame to cooperatively work with the second cam barrel are fitted in the longitudinal guide grooves.