Patent ID: 8218248

Claim:
A zoom lens comprising: in order from an object side, a first lens group having negative refractive power; a second lens group having positive refractive power; and a third lens group having positive refractive power, and a light adjusting unit disposed between the second lens group and the third lens group, wherein the first lens group comprises: a negative lens having an aspherical surface at least on the image side; and a positive lens having large curvature on the object side, wherein the second lens group comprises: a front group comprising a positive lens having an aspherical surface on the object side, the front group having positive refractive power as a whole; and a rear group comprising a doublet lens comprising a positive lens and a negative lens, the rear group having an overall negative refractive power, the rear group being spaced apart from the front group by a predetermined air gap, and wherein the zoom lens satisfies Inequalities, 1.6<|β2 T |<2.7 3.0<|β2 T/β 2 W|< 4.6 0.2 <|CrG 4 R/fT|< 0.45 2.0 <|fG 45 /fG 3|<7.0 35< vdG 3− vdG 2<75 [Inequalities] where β 2T denotes magnification of the second lens group at a tele-position, and β 2W denotes magnification of the second lens group at a wide position, and fT denotes the focal length of the zoom lens at the tele-position, and CrG 4 R denotes the radius of curvature of the contact surface of the doublet lens, and fG 45 denotes the focal length of the rear group, and fG 3 denotes the focal length of the front group, and vdG 3 denotes an Abbe number of the positive lens of the front group with respect to a d-line, and vdG 2 denotes an Abbe number of the positive lens of the first lens group with respect to the d-line.