Tamron Company, Ltd.

Toru Nara

Dayong Li

The present invention is directed to high magnification compact zoom lenses that are reduced in diameter of groups of lens pieces closer to the imaging plane to provide downsized lightweight zoom lenses of magnification as high as 20 diameters, with an image stabilizer or vibration compensating mechanism being also reduced in dimensions. An exemplary improved high magnification zoom lens has four groups of lens pieces, namely, the first or leading lens group Gof positive refractivity in the foremost position closer to the subject, the second lens group Gof negative refractivity, the third lens group Gof positive refractivity, and the fourth lens group Gof positive refractivity in the rearmost position closer to the imaging plane, all arranged in this order. In displacing the entire lens optics of the zoom lens from the wide-angle end to the telephoto end, the second lens group Gare moved toward the imaging plane and the fourth lens group Gare moved to compensate for a varied position of the resultant image while the first and third lens groups, Gand G, have their respective positions fixed along the optical axis. The zoom lens satisfies the requirements as defined in the following formulae: f/f&#x3e;2.0 and v&#x3e;65 where fis a focal length of the third lens group G, fis the focal length of the fourth lens group, vis an average of Abbe contrasts of all the convex lens pieces in the fourth lens group G

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Saitama, Japan

Toru Nara