| 摘要 |
PURPOSE: A zoom lens system is provided to improve the zoom lens system having a high zoom ratio. CONSTITUTION: The zoom lens system includes a positive first zooming lens group(10) and a negative second zooming lens group(20). The first zooming lens group(10) includes a negative first lens group(L1) and a positive second lens group(L2). The second zooming lens group(20) includes a negative third lens group(L3). The second sub-lens group(S2) of the first zooming lens group(10) is fixed in a first zooming-lens-group frame(11). The first sub-lens group(S) is mounted on a moveable sub-lens-group frame(12). The moveable sub-lens group frame(12) is made moveable in the optical axis direction, by a predetermined distance, along a guide groove(13) which is formed on the first zooming-lens-group frame(11). The first sub-lens group(S) is alternatively moved to either the object-side extremity at which the moveable sub-lens group frame(12) comes into contact with the front end of the guide groove(13), or the image-plane-side extremity at which the moveable sub-lens group frame(12) comes into contact with the rear end of the guide groove(13). The third lens group(L3) is fixed in a second zooming-lens-group frame(21). The diaphragm(D) moves together with the first zooming lens group(10).
|
