| 摘要 |
PROBLEM TO BE SOLVED: To obtain a compact zoom lens whose variable power ratio is about 3, whose whole length is shortened and which is provided with high optical performance all over a whole variable power range by properly setting the lens constitution of respective lens groups and effectively utilizing an aspherical surface lens as the so-called zoom lens constituted of two groups. SOLUTION: This zoom lens is provided with the 1st lens group L1 having positive refractive power and the 2nd lens group L2 having negative refractive power. Then, a variable power action is executed to a telephoto end from a wide angle end by moving both lens groups to an object side while reducing a gap between them. The group L2 is provided with at least one aspherical surface. Then, when the focal distances of a whole system at the wide angle end and at the telephoto end are defined as (fW) and (fT), that of the group L2 is defined as f2, the lateral magnification of the group L2 at the wide angle end when an object distance is infinite is defined asβ2W and that at the telephoto end when the object distance is infinite is defined asβ2T, a conditional expression I: 0-31<|f2|/√(fW.fT)<0.36 and a conditional expression II: 2.95<β2T/β2W<3.1 are satisfied.
|
