| 摘要 |
A zoom lens system comprising: a first lens unit having negative optical power; a second lens unit having positive optical power; and a third lens unit having positive optical power, wherein the first to third lens units are individually moved along an optical axis to vary magnification in zooming, each lens unit includes at least one lens element that satisfies the conditions: nd≦1.67, vd<59 and 0.000<PgF+0.002×vd−0.664 (nd, vd and PgF: a refractive index to the d-line, an Abbe number to the d-line and a partial dispersion ratio, of the lens element), and the condition: 0.31<Ir/√(|fG1×fG2|) (Ir=fT×tan(ωT), fT and ωT: a focal length of the entire system and a half value of maximum view angle, at a telephoto limit, fG1 and fG2: a focal length of each of the first lens unit and the second lens unit) is satisfied; an imaging device; and a camera are provided. |
| 主权项 |
1. A zoom lens system having a plurality of lens units, each lens unit being composed of at least one lens element, the zoom lens system, in order from an object side to an image side, comprising:
a first lens unit having negative optical power; a second lens unit having positive optical power; and a third lens unit having positive optical power, wherein the first lens unit is located object-side-most among the plurality of lens units in the entire zoom lens system, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit, the second lens unit, and the third lens unit are individually moved along an optical axis to vary magnification, each of the first lens unit, the second lens unit, and the third lens unit includes at least one lens element that satisfies the following conditions (1), (2) and (3), and the following condition (4) is satisfied:
nd≦1.67 (1)vd<59 (2)0.000<PgF+0.002×vd−0.664 (3)0.31<Ir/√(|fG1×fG2|) (4) where nd is a refractive index to the d-line of the lens element, vd is an Abbe number to the d-line of the lens element, PgF is a partial dispersion ratio of the lens element, which is the ratio of a difference between a refractive index to the g-line and a refractive index to the F-line, to a difference between a refractive index to the F-line and a refractive index to the C-line, Ir is a maximum image height (Ir=fT×tan(ωT)), fT is a focal length of the entire system at a telephoto limit, ωT is a half value (°) of maximum view angle at a telephoto limit, fG1 is a focal length of the first lens unit, and fG2 is a focal length of the second lens unit. |
