Zoom lens and camera device incorporating the same
AssigneeTamron Co., Ltd.
InventorYoshito Iwasawa
Life of this patent
Estimating the term…
Abstract
Provided are: a zoom lens which exhibits a large variable-power ratio, an increased degree of freedom with respect to aberration correction, and which has been achieved having a sufficient reduction in size in the optical axis direction; and an imaging device equipped therewith. The zoom lens includes at least, from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group, and a fifth lens group, in that order. In the zoom lens, prescribed conditions are satisfied.
Claims9
A zoom lens comprising at least five lens groups, namely, the first lens group of positive refractive power, the second lens group of negative refractive power, the third lens group of positive refractive power, the fourth lens group, and the fifth lens group serially arranged in order on the closest to an object first basis, meeting the requirements defined in the formulae as follows:
- 2.0<βrt<3.5 (1)
- −0.8<frt/ft<−0.3 (2)
- where βrt is a composite lateral magnification of all of the lens groups behind the third lens group and closer to the image plane than the same while the zoom lens takes an operative posture at its telephoto end, frt is a composite focal length of all of the lens groups behind the third lens group and closer to the image plane while the zoom lens takes an operative posture at its telephoto end, and ft is a focal length of the zoom lens at the telephoto end.
Dependencies are inferred from the claim text.