Abstract: A wide-angle zoom lens system includes a negative first lens group, a positive second lens group, a negative third lens group and a positive fourth lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, a distance between the negative first lens group and the positive second lens group decreases, a distance between the positive second lens group and the negative third lens group increases, and a distance between the negative third lens group and the positive fourth lens group decreases. The wide-angle zoom lens system satisfies the following conditions: 1.6<X2/fw3.5 . . . (1); 1.2<|f1|/fw<2.0 (f1<0) . . . (2); and 1.6<f2/fw<2.7 . . . (3).

Abstract: A zoom lens system includes a positive first lens group, a negative second lens group, and a rear lens group which is provided on the image side of the negative second lens group, and has a combined positive refractive power, in this order from the object; and the zoom lens system satisfies the following conditions: 5.0<f1/fw<6.5 ??(1) 0.4<fRt/ft<0.55 ??(2) wherein f1 designates a focal length of the positive first lens group; fw designates a focal length of the entire the zoom lens system at the short focal length extremity; fRt designates a combined focal length of the positive rear lens group at the long focal length extremity; and ft designates a focal length of the entire zoom lens system at the long focal length extremity.

Abstract: A wide-angle zoom lens system includes a negative first lens group, a positive second lens group, a negative third lens group and a positive fourth lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, a distance between the negative first lens group and the positive second lens group decreases, a distance between the positive second lens group and the negative third lens group increases, and a distance between the negative third lens group and the positive fourth lens group decreases. The wide-angle zoom lens system satisfies the following conditions: 0.9<f2/ft<1.2??(1) 2.9<f4/fw<3.4??(2) wherein f2: the focal length of the positive second lens group; f4: the focal length of the positive fourth lens group; ft: the focal length of the entire wide-angle zoom lens system at the long focal length extremity; and fw: the focal length of the entire wide-angle zoom lens system at the short focal length extremity.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, a positive third lens group and positive fourth lens group, in this order from the object. The negative first lens group includes a reflection member, and the first lens group remains stationary when zooming is being performed from the short focal length extremity to the long focal length extremity. The zoom lens system satisfies the following conditions: 1.0<f2 /(fw×ft)1/2<1.5 ??(1) 1.2<|f1a|/fw<1.8 (f1a<0 ) ??(2) 2.0<f1b/ft<4.0 ??(3) wherein f2: the focal length of the positive second lens group; fw: the focal length of the entire zoom lens system at the short focal length extremity; ft: the focal length of the entire zoom lens system at the long focal length extremity; f1a: the combined focal length of an object-side lens element with respect to the reflection member; and f1b: the combined focal length of image-side lens elements with respect to the reflection member.

Abstract: A wide-angle lens system includes a negative front lens group and a positive rear lens group, in this order from the object. The negative front lens group includes a negative first sub-lens group and a positive second sub-lens group, in this order from the object. The positive rear lens group includes cemented lens elements having a positive lens element, a negative lens element and a positive lens element. The wide-angle lens system satisfies the following conditions: ?0.8<fla/flb<?0.2??(1) 0.7<f/fR<1.1??(2) wherein fla designates the focal length of the negative first sub-lens group; flb designates the focal length of the positive second sub-lens group; f designates the focal length of the entire wide-angle lens system; and fR designates the focal length of the positive rear lens group.

Abstract: A standard zoom lens system including a positive first lens group, a negative second lens group, a positive third lens group and a positive fourth lens group. Upon zooming from the short focal length extremity to the long focal length extremity, the positive first lens group, the positive third lens group and the positive fourth lens group move toward the object, and the negative second lens group moves toward the image and thereafter moves toward the object. The positive first lens group includes a negative lens element and a positive lens element. The standard zoom lens system satisfies the following conditions: 7.5<f1/|f2|<9.5 ??(1) 3.0<f1/f3<5.0 ??(2) wherein f1 designates the focal length of the positive first lens group; f2 designates the focal length of the negative second lens group; and f3 designates the focal length of the positive third lens group.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, a diaphragm, a negative third lens group, and a positive fourth lens group, in this order from the object. The negative third lens group includes cemented lens elements having a positive lens element and a negative lens element. The positive fourth lens group includes a positive single lens element, and cemented lens elements having a positive lens element and a negative lens element, in this order from the object.

Abstract: A fast zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group and a positive fourth lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, a distance between the positive first lens group and the negative second lens group increases, a distance between the negative second lens group and the positive third lens group decreases, and a distance between the positive third lens group and the positive fourth lens group decreases. The fast zoom lens system satisfies the following conditions; 6.0<f1/fw<10.0??(1) 3.0<f3/fw<8.0??(2) wherein f1 designates the focal length of the positive first lens group; f3 designates the focal length of the positive third lens group; and fw designates the focal length of the entire fast zoom lens system at the short focal length extremity.

Abstract: A telescopic zoom lens system includes first through fourth lens groups, wherein upon zooming from the short to long focal length extremities, the first and fourth lens groups remain stationary, the second lens group moves toward the image side, and the third lens group moves toward the image side and thereafter moves toward the object side. The first lens group includes positive first and second sub-lens groups, the second sub-lens group being a focusing lens group and including a negative meniscus lens element having a convex surface on the object side and a positive lens element having a convex surface on the object side. The following condition (1) is satisfied: 2.7<flR/ft<3.5; ??(1) wherein flR and ft designate the focal lengths of the second sub-lens group and the entire zoom lens system at the long focal length extremity, respectively.

Abstract: A wide-angle zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group and a positive fourth lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, a distance between the positive first lens group and the negative second lens group increases, a distance between the negative second lens group and the positive third lens group decreases, and a distance between the positive third lens group and the positive fourth lens group decreases. The wide-angle zoom lens system satisfies a number of conditions.

Abstract: An intermediate telephoto lens system includes a positive front lens group, a variable-aperture diaphragm, and a positive rear lens group, in this order from the object. The positive front lens group includes a positive first lens element L1, a positive second lens element L2 and a negative third lens element L3, in this order from the object. The positive rear lens group includes cemented lens elements having a negative fourth lens element L4 and a positive fifth lens element L5, and a positive sixth lens element L6, in this order from the object. The intermediate telephoto lens system satisfies the following condition: 2.0<f/f12<3.0 ??(1) wherein f designates the focal length of the entire intermediate telephoto lens system; and f12 designates the combined focal length of the positive first lens element L1 and the positive second lens element L2.

Abstract: A wide-angle lens system includes a negative front lens group and a positive rear lens group, in this order from the object. The negative front lens group includes a negative first sub-lens group and a positive second sub-lens group, in this order from the object. The positive rear lens group includes cemented lens elements having a positive lens element, a negative lens element and a positive lens element. The wide-angle lens system satisfies the following conditions: ?0.8<f1a/f1b<?0.2 ??(1) 0.7<f/fR<1.1 ??(2) wherein f1a designates the focal length of the negative first sub-lens group; f1b designates the focal length of the positive second sub-lens group; f designates the focal length of the entire wide-angle lens system; and fR designates the focal length of the positive rear lens group.

Abstract: A telescopic zoom lens system includes first through fourth lens groups, wherein upon zooming from the short to long focal length extremities, the first and fourth lens groups remain stationary, the second lens group moves toward the image sides, and the third lens group moves toward the image side and thereafter moves toward the object side. The first lens group includes positive first and second sub-lens groups, the second sub-lens group being a focusing lens group and including a negative meniscus lens, element having a convex surface on the object side and a positive lens element having a convex surface on the object side. The following condition (1) is satisfied: 2.7<f1R/ft<3.5 . . . (1); wherein f1R and ft designate the focal lengths of the -second sub-lens group and the entire zoom lens system at the long focal length extremity, respectively.

Abstract: A zoom lens system includes a negative first lens group, a variable diaphragm, a positive second lens group, in this order from the object. Zooming is performed by moving the negative first lens group and the positive second lens group. The negative first lens group is constituted by at least two negative lens elements and at least two positive lens elements. The zoom lens system satisfies the following conditions: 1.5<|f1/fw|<1.8??(1) 1.0<|f2/(fw×ft)1/2<1.3??(2) 1.0<|f2/f1|<1.2??(3) wherein f1 designates the focal length of the negative first lens group; f2 designates the focal length of the positive second lens group; fw designates the focal length of the entire the zoom lens system at the short focal length extremity; and ft designates the focal length of the entire the zoom lens system at the long focal length extremity.

Abstract: A wide-angle zoom lens system includes a negative first lens group, a positive second lens group, a negative third lens group and a positive fourth lens group), in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, a distance between the negative first lens group and the positive second lens group decreases, a distance between the positive second lens group and the negative third lens group increases, and a distance between the negative third lens group and the positive fourth lens group decreases. The wide-angle zoom lens system satisfies the following conditions: 1.3<|f1|/fw<1.7 (f1<0)??(1) 2.5<f4/fw<3.3??(2) wherein f1 designates the focal length of the negative first lens group; f4 designates the focal length of the positive fourth lens group; and fw designates the focal length of the entire wide-angle zoom lens system at the short focal length extremity.

Abstract: A wide-angle zoom lens system includes a negative first lens group, a positive second lens group, a negative third lens group and a positive fourth lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, a distance between the negative first lens group and the positive second lens group decreases, a distance between the positive second lens group and the negative third lens group increases, and a distance between the negative third lens group and the positive fourth lens group decreases. The wide-angle zoom lens system satisfies the following conditions: 1.1<|f1|/fw<2.0(f1<0) ??(1) 2.0<f4/fw<3.5 ??(2) 2.5<fBw/fw<3.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, a positive third lens group and positive fourth lens group, in this order from the object. The negative first lens group includes a reflection member, and the first lens group remains stationary when zooming is being performed from the short focal length extremity to the long focal length extremity. The zoom lens system satisfies the following conditions: 1.0<f2 /(fw×ft)1/2<1.5??(1) 1.2<|f1a|/fw<1.8 (f1a<0 )??(2) 2.0<f1b/ft<4.0??(3) wherein f2: the focal length of the positive second lens group; fw: the focal length of the entire zoom lens system at the short focal length extremity; ft: the focal length of the entire zoom lens system at the long focal length extremity; f1a: the combined focal length of an object-side lens element with respect to the reflection member; and f1b: the combined focal length of image-side lens elements with respect to the reflection member.

Abstract: A fast zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group and a positive fourth lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, a distance between the positive first lens group and the negative second lens group increases, a distance between the negative second lens group and the positive third lens group decreases, and a distance between the positive third lens group and the positive fourth lens group decreases. The fast zoom lens system satisfies the following conditions; 6.0<f1/fw<10.0??(1) 3.0<f3/fw<8.0??(2) wherein f1 designates the focal length of the positive first lens group; f3 designates the focal length of the positive third lens group; and fw designates the focal length of the entire fast zoom lens system at the short focal length extremity.

Abstract: A wide-angle zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group and a positive fourth lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, a distance between the positive first lens group and the negative second lens group increases, a distance between the negative second lens group and the positive third lens group decreases, and a distance between the positive third lens group and the positive fourth lens group decreases. The wide-angle zoom lens system satisfies the following conditions: 6.3<f1/fw<8.0??(1) 7.0<f1/|f2|<9.0 (f2<0)??(2) 2.5<f3/fw<4.

Abstract: A wide-angle zoom lens system includes a negative first lens group, a positive second lens group, a negative third lens group and a positive fourth lens group), in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, a distance between the negative first lens group and the positive second lens group decreases, a distance between the positive second lens group and the negative third lens group increases, and a distance between the negative third lens group and the positive fourth lens group decreases. The wide-angle zoom lens system satisfies the following conditions: 1.3<|f1|/fw<1.7 (f1<0) ??(1) 2.5<f4/fw<3.3 ??(2) wherein f1 designates the focal length of the negative first lens group; f4 designates the focal length of the positive fourth lens group; and fw designates the focal length of the entire wide-angle zoom lens system at the short focal length extremity.