Patent attributes
A telescopic zoom lens system includes first through fourth lens groups, wherein upon zooming from the short to long focal length extremities, the first and fourth lens groups remain stationary, the second lens group moves toward the image side, and the third lens group moves toward the image side and thereafter moves toward the object side. The first lens group includes positive first and second sub-lens groups, the second sub-lens group being a focusing lens group and including a negative meniscus lens element having a convex surface on the object side and a positive lens element having a convex surface on the object side. The following condition (1) is satisfied:2.7<flR/ft<3.5; (1)wherein flR and ft designate the focal lengths of the second sub-lens group and the entire zoom lens system at the long focal length extremity, respectively.
