| 摘要 |
There is provided a zoom lens system including at least a first lens group GR1 having a positive refractive power, a second lens group GR2 having a negative refractive power, a third lens group GR3 having a positive refractive power, a fourth lens group GR4 having a negative refractive power, a fifth lens group GR5 having a positive refractive power, and a sixth lens group GR6 having a negative refractive power, arranged sequentially from the object side. Zoom ratio is varied by changing the distance between the adjacent lens groups. The distance, taken as DW(i-j), between the i- and j-th lens groups at the wide angle end during at-infinity imaging and that, taken as DT(i-j), between the i- and j-th lens groups at the telephoto end during at-infinity imaging meet the following conditions (1), (2), (3), (4) and (5) <?in-line-formulae description="In-line Formulae" end="lead"?>DW(1-2)<DT(1-2) (1)<?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>DW(2-3)>DT(2-3) (2)<?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>DW(3-4)>DT(3-4) (3)<?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>DW(4-5)<DT(4-5) (4)<?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>DW(5-6)<DT(5-6) (5)<?in-line-formulae description="In-line Formulae" end="tail"?> and focusing is made by moving the fourth lens group GR4 axially of the lenses.
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