Patent ID: 7859767

Claim:
A zoom lens comprising, in an order from an object side to an image side, a first lens group having a positive refracting power, a second lens group having a negative refracting power, and a rear group including at least one lens group, wherein a zooming operation is performed by changing a spacing of the lens groups, wherein said zoom lens includes an aperture stop and, when said second lens group is taken as a first focus group and a sub-lens group constituting a portion of one lens group of said rear group that moves during the zooming operation is taken as a second focus group and another portion of that one lens group does not move during any focusing, each of said first focus group and said second focus group includes a positive lens and a negative lens, and wherein when mean Abbe numbers of materials of the positive lens and the negative lens of said first focus group are denoted by Vmp and Vmn, respectively, mean Abbe numbers of materials of the positive lens and the negative lens of said second focus group are denoted by Vsp and Vsn, respectively, a difference of a distance from said aperture stop to a surface vertex of said first focus group which is closest to the object side as said zoom lens is focused from infinity to a shortest photographic distance is denoted by ΔXm, a difference of a distance from said aperture stop to a surface vertex of said second focus group which is closest to the object side as said zoom lens is focused from infinity to the shortest photographic distance is denoted by ΔXs, a relation Δ Xm *( Vmn−Vmp )*Δ Xs *( Vsn−Vsp )>0 is satisfied.