Patent ID: 6995921

Claim:
A zoom lens apparatus, comprising: a first optical lens group having a negative focal length arranged at a first position closest to a subject; a second optical lens group having a positive focal length arranged at a second position second closest to the subject; an aperture diaphragm which is disposed to a subject side of the second optical lens group closer to the subject in a manner such that the aperture diaphragm is movable integrally with the second optical lens group; and a third optical lens group having a positive focal length arranged at a third position third closest to the subject, wherein at least the first and second optical lens groups are moved to change a magnification of the zoom lens apparatus, wherein the second optical lens group comprises a three-group and four-lens structure which comprises: a positive lens arranged at a first sub-position closest to the subject in the second optical lens group and such that a greater-curvature surface of the positive lens faces the subject; a negative meniscus lens arranged at a second sub-position second closest to the subject in the second optical lens group and such that a concave of the negative meniscus lens faces the subject; a positive meniscus lens conjoined with the negative meniscus lens and arranged at a third sub-position third closest to the subject in the second optical lens group; and a positive lens arranged at a fourth sub-position fourth closest to the subject in the second optical lens group, wherein the zoom lens system satisfies an inequality condition 0.15<(N 22 −N 23 )<0.40, wherein N22 is a refractive index of the negative meniscus lens of the second optical lens group and N23 is a refractive index of the positive meniscus lens of the second optical lens group conjoined with the negative meniscus lens.