| 摘要 |
A small sized zoom optical system is provided to decrease an assembly time of the optical system by properly adjusting Abbe numbers for lenses in a second lens group or a movement of the second lens group during a zooming process. A small sized zoom optical system includes first to third lens groups(10-1-30-1), which are sequentially arranged from an object side. The first lens group has a negative refractive power. The second lens group has a positive refractive power. The third lens group has a positive refractive power. The second lens group is composed of coupling lenses, which are formed by coupling two lenses with each other. A relation, 10 <= v1-v2 <= 23, is satisfied, where v1 and v2 are Abbe numbers of first and last lenses in the second lens group from the object side.
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