Keck, Mahin & Cate
Zoom lens
 A zoom lens includes, from the image side to the subject side, a first lens group having a negative overall power and a second lens group having a positive overall power. The lens groups are movable relative to each other in opposite directions so as to increasingly and decreasingly change an axial air spacing between the two lens groups, thereby continuously varying the focal length of the zoom lens. The zoom lens satisfies the following conditions: EQU 2.5<bf.sub.w /f.sub.w, and EQU 0.68<f.sub.1 /f.sub.2 <0.98, where bf.sub.w is the axial distance measured from the rearmost surface of the second lens group to a conjugate point at a long conjugate length of the second lens group for the wide-angle end, f.sub.w is the overall focal length of the zoom lens for the wide-angle end, f.sub.1 is the overall focal length of the first lens group, and f.sub.2 is the overall focal length of the second lens group. 
Fuji Photo Optical Company, Ltd.
G
G02B
inventional
Hiroshi
Yamada