| 摘要 |
PROBLEM TO BE SOLVED: To obtain a small-sized zoom lens having a good performance over the whole zooming region and the whole object distance by using a diffraction optical element, and to obtain an optical instrument using the zoom lens. SOLUTION: The zoom lens which has a 1st lens group having a negative refractive power, a 2nd lens group having a positive refractive power and a 3rd lens group having a negative refractive power in this order from an object side, and wherein each lens group is shifted to the object side at zooming from a wide angle end to a telephoto end, is provided with one or more diffraction optical parts. COPYRIGHT: (C)2004,JPO
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