| 摘要 |
The object of the present invention is to provide a zoom lens system being extremely reduced size such as a standard single focal length lens, having very few number of lens elements, being ultimately reduced cost, having a zoom ratio about 2.2, and also having high optical performance without using any aspherical surface. The zoom lens system has, in order from an object side, a first lens group G1 having a negative refractive power and a second lens group G2 having a positive refractive power, and performs zooming by changing an air space between the first lens group G1 and the second lens group G2. The first lens group comprises, in order from the object side, a negative lens group Ln consisting of one or two negative lens elements and a positive lens L12 having a convex surface facing to the object side. All surfaces consisting of the first lens group G1 are spherical or plane surfaces. Predetermined conditional expressions are satisfied.
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