Patent attributes
A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, the distance between the negative first lens group and the positive second lens group decreases, and the distance between the positive second lens group and the positive third lens group increases. The negative first lens group includes a negative first lens element, a negative second lens element having a weaker negative refractive power, and a positive third lens element, in this order from the object. The second lens element of the negative first lens group satisfies the following condition:0<(ra−rb)/(ra+rb)<0.3 (1)whereinra designates a radius of curvature of the object-side surface of the second lens element of the negative first lens group; andrb designates a radius of curvature of the image-side surface of the second lens element of the negative first lens group.
