| 摘要 |
PROBLEM TO BE SOLVED: To provide a high performance zoom lens which can reduce variations in image angles and aberrations when focusing while reducing its size. SOLUTION: This zoom lens is built by arranging a 1st group G1 having positive refracting power, a 2nd group G2 having negative refracting power, a 3rd group G3 having positive or negative refracting power, and a 4th group G4 having positive refracting power in this order from the side of an object. The 1st group G1 comprises a negative lens group G11 fixed when focusing, a 1st positive lens group G12 moving on the optical axis when focusing, and a 2nd positive lens group G13 fixed when focusing all arranged in this order from the side of the object. The 1st positive lens group G12 is composed of three lenses of a negative lens G121, a 1st positive lens G122, and a 2nd positive lens G123 arranged in this order from the side of the object. It changes its magnification by moving the 2nd group G2 and the 3rd group G3 on the optical axis, and focuses by moving the 1st positive lens group G12 in the 1st group G1 on the optical axis. COPYRIGHT: (C)2005,JPO&NCIPI
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