| 摘要 |
PROBLEM TO BE SOLVED: To obtain a zoom lens which possesses four or five lens groups as a whole, in which the refracting power of each lens group and the moving condition of each lens group due to variable power are appropriately set, whose viewing angle is wide and whose variable power ratio is high and an optical apparatus using it. SOLUTION: This zoom lens comprises the front group of negative refracting power and the back group of positive refracting power arranged in this order from an object side, and the front group comprises one lens group that is the first group of the negative refracting power, and the back group possesses four lens groups which are the second group of the positive refracting power, the third group of the negative refracting power and the fourth group and the fifth group of the positive refracting power. Variable power is performed by changing a gap between respective lens groups, and the fourth group incorporates the biconvex positive lens of the positive refracting power, and the fifth group incorporates a negative lens whose concave surface is faced to the object side and a positive lens whose convex surface is faced to an image side, arranged in this order from the object side, and intervals DiW and Dit between an i-st group and an i+1-st group at a wide angle end and a telephoto end and an optical entire length TLW and the focal distance fW of an entire system at the wide angle end are respectively and properly set.
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