| 摘要 |
A zoom lens having an effective focal length fw for the wide angle mode comprises a first lens group, a second lens group and a third lens group. The first lens group has a negative effective power and an effective focal length f 1 , wherein 2.1<|f 1 /fw|<2.6. The first lens group comprises a first lens and a second lens. The first lens has a first negative power and at least a first concave aspheric lens surface. The second lens has a first positive power. The second lens group has a first positive effective power and an effective focal length f 2 , wherein 1.5<|f 2 /fw|<1.8. The second lens group comprises a third lens and a fourth lens. The third lens has a second positive power and at least a second aspheric lens surface. The fourth lens has a third positive power. The third lens group has a second positive effective power.
|
