Patent ID: 8369020

Claim:
A zoom lens comprising: a first variable refractive power element formed of different media and configured to change a refractive power thereof in a positive direction by changing a shape of an interface between the different media during zooming from a wide angle end to a telephoto end; and a second variable refractive power element formed of different media and configured to change a refractive power thereof in a negative direction by changing a shape of an interface between the different media during zooming from a wide angle end to a telephoto end, wherein an imaging magnification of at least one of the first and second variable refractive power elements increases during zooming from the wide angle end to the telephoto end, and wherein the following conditional expression is satisfied −0.0150<{Σ(Δφ1 j/ν 1 j )+Σ(Δφ2 j/ν 2 j )}· ft< 0.0075, where j is an integer equal to or greater than 1 indicative of the order of the medium of the variable refractive power element counted from the side of the variable refractive power element on which light is incident, and where Δφ1j is the amount of change in the refractive power of each of the media of the first variable refractive power element during zooming from the wide angle end to the telephoto end, ν1j is the Abbe number of each of the media of the first variable refractive power element, Δφ2j is the amount of change in the refractive power of each of the media of the second variable refractive power element during zooming from the wide angle end to the telephoto end, ν2j is the Abbe number of each of the media of the second variable refractive power element, and ft is the focal length of the zoom lens at the telephoto end.