Zoom lens of the retrofocus type having four lens groups

摘要

Zoom lens of the retrofocus-type comprising a negative first lensgroup (Gl), a positive second lens-group (G2), a negative third lensgroup (G3) and a positive fourth lens group (G4), in that order from the object side, wherein upon zooming from the short focal-length to the long focal-length, the distance between said first lens-group (Gl) and said second lens-group (G2) decreases, the distance between said second lens-group (G2) and said third lens-group (G3) increases and the distance between said third lens-group (G3) and said fourth lens-group (G4) decreases, wherein said third lens-group (G3) includes a cemented doublet consisting of a positive lens (31) and a negative lens (32) and wherein the following inequalities are fulfilled: (1) -2.50 < fl/f2 < -1.57 (2) f3/f3B < -0.1 wherein fl denotes the focal-length of said first lens-group (Gl), f2 denotes the focal-length of said second lens-group (G2), f3 denotes the focal-length of said third lens-group (G3) and f3B denotes the focallength of the bonding surface in the cemented doublet (31, 32) within said third lens-group (G3). Upon zooming from the short focal-length to the long focal-length, the first lens-group (Gl) monotonically moves towards the image-side, the second lens-group (G2) and the fourth lens-group (G4) become integral with each other and monotonically move towards the object-side and the third lens-group (G3) remains stationary.