Patent ID: 9606337
Date: 2017-03-28
CPC Classifications: G02B

Claim:
1. A zoom lens consisting of, in order from an object side, 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, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power, wherein, during magnification change, the first lens group and the fifth lens group are fixed relative to an image plane, and the second lens group, the third lens group, and the fourth lens group are moved to change distances therebetween, during magnification change from a wide-angle end to a telephoto end, the second lens group is moved from the object side toward the image plane side, and the fourth lens group is moved from the image plane side toward the object side, the fifth lens group comprises at least two negative lenses, and the condition expression (1) below is satisfied: where LABnd is an average value of a refractive index LAnd with respect to the d-line of an LA negative lens, which is the first negative lens from the image plane side of the fifth lens group, and a refractive index LBnd with respect to the d-line of an LB negative lens, which is the second negative lens from the image plane side of the fifth lens group.