| 摘要 |
A compact and lightweight, high variable power zoom lens especially suitable for single-lens reflex digital cameras, which is 75 degrees or even wider in field angle at the wide-angle end, approximately 3 to 4 in F-number at the wide-angle end and approximately 6 to 7 at the telephoto end, and about 15x in variable power ratio. The zoom lens of four groups of lens pieces respectively exerting positive, negative, positive, and positive refractivities varies the power from the wide-angle end to the telephoto end as a result of the 1st and 2nd lens groups being split more, the 2nd and 3rd lens groups coming closer to each other, and the 3rd and 4th lens groups also coming closer to each other. The 3rd lens group has the leading set of lens pieces of positive refractivity closer to objects and the trailing set of lens pieces of negative refractivity, and the trailing set alone are moved to be orthogonal to the optical axis to compensate for defocus in the imaging plane caused by a tremor of the user's hand(s). The 2nd lens group are displaced closer to objects for the focusing.
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