Close focusing zoom lens

A zoom lens comprising a first group of positive power movable axially for focusing,

• a second negative group,
• a third positive group and a fourth positive group,
• said second and third groups being movable axially of said lens for varying the equivalent focal length thereof,
• and
• 0.55>F.sub.1 /F.sub.L >0.4
• where F.sub.1 is the equivalent focal length of the first group, F.sub.L is the longest equivalent focal length of the lens, and
• 1.5>K.sub.1 /K.sub.M >1.0
• 4.0>.vertline.K.sub.2 /K.sub.M .vertline.>2.2
• 1.7>K.sub.3 /K.sub.M >1.0
• 1.3>K.sub.4 /K.sub.M >0.4
• where K.sub.1, K.sub.2, K.sub.3, and K.sub.4 are the powers of said first, second, third, and fourth groups, and K.sub.M is the geometric mean of the powers of the lens at the extremes of its focal lengths said fourth group having a telephoto ratio of less than 0.9

A zoom lens comprising a front focusing group of positive power movable axially, a second negative group, a third group, said second and third groups being movable axially of said lens for varying the equivalent focal length, and a fourth positive group, said first group comprising a positive doublet and a positive singlet, said doublet and singlet having the following relationship

• 2.0>K.sub.S /K.sub.D >0
• where K.sub.S is the power of the singlet and K.sub.D is the power of the doublet, and
• 0.55>F.sub.1 /F.sub.L >0.50
• where F.sub.1 is the equivalent focal length of the first group, F.sub.L is the longest equivalent focal length of the lens, and said fourth group has a telephoto ratio less than 0.9.