| 摘要 |
A zoom lens of rear focus type in which a total lens system is able to be miniaturized by further miniaturizing a prism, without deteriorating an optical performance. The zoom lens has a first lens group (GR 1 ) to a fifth lens group (GR 5 ) having refraction powers of a positive, negative, positive, positive and negative from the object side in this order, respectively, and is configured to carry out a zooming operation by moving the second lens group (GR 2 ) and the fourth lens group (GR 4 ). In addition, the first lens group has a front-side lens group having an negative refracting power, an optical element for folding an optical path, and a backside lens group having a positive refracting power, from the object side in this order, and further a condition of 1.3<beta 5 <2.2 is satisfied, provided that an imaging magnification of the fifth lens group (GR 5 ) at where an object distance is at infinity is beta 5 . Therefore, the focal length of the lens groups positioned closer to the object is shortened and an effective diameter of the first lens group (GR 1 ) can be made small, whereby it is possible to make the optical element (for example, prism P 1 ) thinner.
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