| 摘要 |
PROBLEM TO BE SOLVED: To realize high image quality in a zoom lens whose variable power ratio is about 5. SOLUTION: This zoom lens is constituted of a 1st positive lens group G1, a 2nd negative lens group G2, a 3rd positive lens group G3, a 4th positive lens group G4 and a 5th lens group G5 having weak refractive power, in this order from object side, and performs zooming by moving the 2nd and the 4th lens groups G2 and G4. The 5th lens group G5 is constituted of at least two groups of lenses, including a positive lens group including at least one positive lens and a negative lens group including at least one negative lens, where the zoom lens satisfies (1) 0.8<β5<1.05, and (2) 0.8<|fG2/fw|<1.3. Andβ5 is the image forming magnification of the 5th lens group, where the subject distance is infinity, fG2 is the focal distance of the 2nd lens group, and (fw) is the focal distance of a lens entire system at a short focal distance end.
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