| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a zoom lens which has a half field angle of≥38 degrees at a wide angle end, and a variable magnification ratio of >9 times. <P>SOLUTION: The zoom lens includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a fourth lens group G4 having a positive refractive power, which are disposed in that order from an object side, with an aperture stop S disposed between the second and third lens groups. The respective lens groups are moved independently for zooming. The positions of the first and third lens groups G1 and G3 at the telephoto end are closer to the object than those at the wide angle end. The first lens group G1 has a negative meniscus lens and a positive lens, which are disposed in that order from the object side. The second lens group G2 has a negative lens, a negative lens, and a positive lens, which are disposed in that order from the object side. The zoom lens satisfies the following condition (1): 0.3<¾(β2t/β2w)/(ft/fw)¾<0.8 whereinβ2w is an imaging magnification of the second lens group G2 at the wide angle end,β2t is an imaging magnification of the second lens group at the telephoto end, fw is a focal length of the entire system at the wide angle end, and ft is a focal length of the entire system at the telephoto end. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
