| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a zoom lens making higher variable power ratio, securing an image angle to be wide on a telephoto end, being small sized and having high performance and furthermore, maintaining performance well when image shifting. <P>SOLUTION: The zoom lens includes: a first lens group G1 having positive refractive power; a second lens group G2 having negative refractive power; a diaphragm SP fixed to an image surface; a third lens group G3 having positive refractive power; a fourth lens group G4 having positive refractive power; and a fifth lens group G5 having negative refractive power in this order from the object side. In this case, when varying power from a wide angle end to a telephoto end, the zoom lens has the first lens group, the third lens group and the fifth lens group G5 fixed in the direction of the optical axis, a second lens group has varying power effect by moving from the object side to the image side. The fourth lens group is moved in the direction of the optical axis so that variation in an image surface position along with movement of the second lens group is compensated as well as having a focusing function. The first lens group is composed of at least one piece of a negative lens and three pieces of positive lenses and a biconcave negative lens and a positive lens are bonded together on the most object side of the first lens group. <P>COPYRIGHT: (C)2013,JPO&INPIT |
