Medium-and-long-focus zoom lens

The invention discloses a medium-long-focus zoom lens which comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and a seventh lens which are sequentially arranged along an optical axis from an object side to an image side, the seventeen lenses sequentially comprise a front fixing group, a zoom group, a rear fixing group and a compensation group, and the front fixing group is fixed in position and has positive diopter; the zoom group can move along the direction of an optical axis to adjust the focal length of the lens and has negative diopter, the rear fixing group is fixed in position and has positive diopter, and the compensation group can move along the direction of the optical axis to compensate the offset of the image surface position of the lens in the zooming process and has negative diopter. And an aperture diaphragm is arranged between the sixth lens and the seventh lens. According to the long-focus zoom lens, the full-glass lens and the F #