| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens which is small and also has high resolution while obtaining a high variable magnification ratio which can fully cover a sufficient wide viewing angle at a wide angle end and a regular photographing area in a zoom lens in which a positive 1st lens group G1, a negative 2nd lens group G2 , an aperture diaphragm, a positive 3rd lens group G3 are arranged successively from an object side and the 1st lens group G1 and the 3rd lens group G3 are moved so that the interval between the 1st lens group G1 and the 2nd lens group G2 becomes large and the interval between the 2nd lens group G2 and the 3rd lens group G3 becomes small in response to the variable magnification from the wide angle end. SOLUTION: The 3rd lens group G3 is constituted by arranging successively 4 sheets of 3 groups of the cemented lens of a positive lens, a positive lens and a negative lens and a positive lens from the object side and both surfaces of the surface of the most object side and the surface of the most image side of the 3rd lens group G3 are aspherical surfaces of the shape such as that positive refractive power becomes weak gradually as it separates from an optical axis and (the maximum image height/the radius of curvature of the surface of the most image side of the 3rd lens group G3) is larger than -0.5 and smaller than 0. COPYRIGHT: (C)2005,JPO&NCIPI
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