| 摘要 |
A zoom lens system of the present invention comprises, from the object side, a first positive lens unit, a second negative lens unit, a third positive lens unit, a fourth positive lens unit and a fifth negative lens unit, wherein all of the lens units move toward the object during zooming from the shortest focal length condition toward the longest focal length condition, and said zoom lens system meets the following conditions. -0.30<f2/f1<-0.10 (1) 1.25< beta 5T/ beta 5W<2.00 (2) 0.25<( beta 5Tx beta 2W)/( beta 2Tx beta 5W)<0.65 (3) -1.20<f12W/fw<-0.60 (4) where, f1: focal length of the first lens unit; f2: focal length of the second lens unit; fw: shortest focal length of the entire system; beta 5W: horizontal magnification of the fifth lens unit in the shortest focal length condition; beta 5T: horizontal magnification of the fifth lens unit in the longest focal length condition; beta 2W: horizontal magnification of the second lens unit in the shortest focal length condition; beta 2T: horizontal magnification of the second lens unit in the longest focal length condition; and f12W: combined focal lengths of the first lens unit and the second lens unit in the shortest focal length condition.
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