Patent ID: 8520313

Claim:
A zoom lens configured to zoom from a wide angle end to a telephoto end, comprising: a first refractive power variable element whose refractive power is changed in a positive direction by changing a shape of a boundary surface of different media when zooming from the wide-angle end to the telephoto end, and a second refractive power variable element whose refractive power is changed in a negative direction by changing a shape of a boundary surface of different media when zooming from the wide-angle end to the telephoto end, wherein, when zooming from the wide-angle end to the telephoto end, imaging magnifications of the first refractive power variable element and the second refractive power variable element are increased, and wherein the following conditional expression is satisfied; 0.05<Δφ1min·√( fw·ft )<0.5 −0.5<Δφ2min·√( fw·ft )<−0.05 wherein, in zooming from the wide-angle end to the telephoto end, when a plurality of the first refractive power variable elements are provided, an amount of change of a refractive power of the first refractive power variable element having a smallest amount of change in the refractive power is Δφ1min, or, when only one first refractive power variable element is provided, the amount of change of the refractive power of the first refractive power variable element is Δφ1min, and when a plurality of the second refractive power variable elements are provided, an amount of change of a refractive power of the second refractive power variable element having a smallest amount of change in the refractive power is Δφ2min, or when only one second refractive power variable element is provided, the amount of change of the refractive power of the second refractive power variable element is Δφ2min.