High zoom ratio lens

A high zoom ratio lens, including first to fourth lens groups each comprised of a plurality of lenses, the lens groups having respective refractive powers of positive, negative, positive, and positive levels in order from the closest to an object, in zooming from a wide-angle end to a telephoto end, the first and second lens group having a space (air-filled) widened therebetween, the second and third lens groups having a space (air-filled) narrowed therebetween, and the third and fourth lens groups having space (air-filled) narrowed therebetween while the first, third, and fourth lens groups move toward the object, and in focusing, the second lens group alone moving, under the conditions described as follows:

• 0.05<|f2|/(fT−fW)<0.07 (1) 0.3<f1/(fT−fW)<0.5 (2) 0.2<f4/(fT−fW)<0.3 (3) 0.37<Z2/Z<0.47 (4)
• where fW is a focal length of the entire optics at a wide-angle end, fT is a focal length of the entire optics at a telephoto end, f2 is a focal length of the second lens group, f1 is a focal length of the first lens group, f4 is a focal length of the fourth lens group, Z2 is equal to β2T/β2W where β2W is an imaging magnification of the second lens group at the wide-angle end (β2W<0), β2T is an imaging magnification of the second lens group at the telephoto end (β2T<0), and Z is equal to fT/fW.