| 摘要 |
PROBLEM TO BE SOLVED: To provide a simply constituted zoom lens having a desired zooming ratio and a desired optical performance. SOLUTION: The zoom lens is equipped with a 1st lens group L1 having positive refractive power, a 2nd lens group L2 having negative refractive power, a 3rd lens group L3 having positive refractive power and a 4th lens group L4 having positive refractive power in this order from an object side to an image side, wherein at least the 2nd lens group is shifted at zooming. The 2nd lens group L2 is constituted of: a negative lens 21 where the face on the image side has a larger absolute value of the refractive power than that of the face on the object side; a negative lens 22 having a concave face on the object side; and a positive lens 23 having a convex face on the object side in this order from the object side to the image side. The negative lens 22 and the positive lens 23 are arranged leaving a distance. Provided that the Abbe's number of the material of the positive lens 23 is expressed byν23 and refractive indexes of the materials of the negative lens 21 and the negative lens 22 by N21 and N22, respectively, the following conditions are satisfied;ν23<20.0 and 1.65<(N21+N22)/2. COPYRIGHT: (C)2005,JPO&NCIPI
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