| 主权项 |
1. An imaging lens comprising:
a first lens group having positive refractive power; a second lens group having positive refractive power; and a third lens group having negative refractive power, arranged in this order from an object side to an image plane side, wherein said first lens group includes a first lens having positive refractive power, a second lens having negative refractive power, and a third lens having positive refractive power, said second lens group includes a fourth lens having positive refractive power and a fifth lens having positive refractive power, said third lens group includes a sixth lens and a seventh lens, and said first lens has an Abbe's number νd1, said second lens has an Abbe's number νd2, said third lens has an Abbe's number νd3, said fourth lens has an Abbe's number νd4, and said fifth lens has an Abbe's number νd5 so that the following conditional expressions are satisfied:
40<νd1<75,20<νd2<35,40<νd3<75,40<νd4<75,20<νd5<35. |
