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Compact zoom lens system

Image Number 5 for United States Patent #5412508.

A zoom lens system consists of five lens elements arranged in two groups. Counting from the object side, the first three elements form a front lens group with positive refracting power and the last two elements form a rear lens group with negative refracting power. An airspace is reserved between the front lens group and the rear lens group and it is made variable for zooming. The first lens element in the front lens group is a negative meniscus lens element having its concave lens surface directed toward the object side. Both the second and third lenses in the front lens group are positive lens element. The fourth lens in the rear lens group is positive meniscus lens element, and the fifth lens is a lens element with negative refracting power. In the lens composition, both the front lens group and the rear lens group at least include an aspherical surface respectively.

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