Patent ID: 7738185

Claim:
A zoom lens, comprising: four lens groups including a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power, sequentially arranged from an object side, wherein when a positional state of lenses is varied from a wide-angle-end state to a telephoto-end state, the second lens group is moved to an image side, the fourth lens group is moved for compensating a variation in a position of an image plane caused by the movement of the second lens group, and the first lens group and the third lens group are fixed along the optical axis; and an aperture stop disposed at the object side of the third lens group, wherein the third lens group includes a negative sub-lens group having a negative refractive power, and a positive sub-lens group disposed at the image side of the negative sub-lens group with an airspace interposed therebetween, the positive sub-lens group having a positive refractive power, and wherein the first lens group includes four lenses including cemented lenses of a negative lens and a positive lens, a positive lens, and a positive lens, sequentially arranged from the object side, and the following conditional expression (1) is satisfied: 0.4 <Da/TL< 0.5 (1) where Da is a distance between the aperture stop and the image plane, and TL is an overall optical length comprising the distance between a lens surface closest to the object side and the position of the image plane, along the optical axis.