| 摘要 |
PROBLEM TO BE SOLVED: To make a zoom system which is made small-sized and simple and has stable high image forming performance from an infinite distance to a short distance and the depth of which is reduced when the lens system is stored by making the total thickness of individual lens groups small. SOLUTION: A zoom lens of an electronic image pickup unit having the zoom lens and an electronic imaging element comprises a negative 1st group G1, a positive 2nd group G2, and a positive 3rd group G3. The 2nd group G2 comprises two lens elements, the image-side lens element of which is in a meniscus shape which is concave to the image plane side. The 3rd group G comprises one positive lens element. The 2nd group G2 moves only to the object side during power variation from a wide-angle end to a telephoto end when focused or an object at infinity, and the 3rd group G3 moves by a quantity different from that of the 2nd group G2 when the power is varied. In the focusing operation, the 3rd group G3 moves and all refracting surfaces of the 3rd group G3 meets a condition (1) concerning an aspherical surface deviation quantity. COPYRIGHT: (C)2003,JPO
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