| 摘要 |
PROBLEM TO BE SOLVED: To provide a high variable power zoom lens system having superior optical characteristics and a variable power ratio larger than 13 times, a focal distance of about 350 mm at a long focal distance end, an F value of about 5.6, and a field angle of about 60 degrees at a short focal distance end.SOLUTION: The high variable power zoom lens system includes a first lens group G1 of positive refractive power, a second lens group G2 of negative refractive power, a third lens group G3 of positive refractive power, and a fourth lens group G4 of positive refractive power which are arranged, in this order starting from an object side. When the magnification from the short focal distance end to the long focal distance end is changed, the distance between the lens groups increases between the first lens group G1 and the second lens group G2, and the distance between the lens groups decreases between the second lens group G2 and the third lens group G3. The third lens group G3 includes a 3a-th group G3a of positive refractive power and a 3b-th group G3b of negative refractive power, both of which are arranged in this order starting from the object side. The 3a-th group G3a has a positive lens which is the closest to the object side, and a cemented lens composed of a positive lens and a negative lens which is the closest to an image side, and satisfies a predetermined conditional expression. |
