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 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 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/fw<3.5??(1) 1.2<|f1|/fw<2.0 (f1<0)??(2) 1.6<f2/fw<2.

Abstract: An image pickup apparatus includes a multifocal optical system in which first and second focal lengths on short and long focal length sides is optically selected; an image pickup device for converting an optical image into an image signal; an image processor which processes the image signal to form an original image; a trimming device for trimming the original image formed by the image processor; a drive controller for switching the optical focal length when the set angle-of-view of the trimming device changes between the second angle-of-view and a third angle-of-view which is smaller than the second angle-of-view; and a memory for storing an original image formed by the image processor at a focal length before the optical focal length is switched by the drive controller. The trimming device forms trimmed images of set angle-of-views while the optical focal length is switched.

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. Upon zooming from the short focal length extremity to the long focal length extremity, the distance between the negative first lens group and the positive second lens group decreases, the distance between the positive second lens group and the negative third lens group increases, and the distance between the negative third lens group and the positive fourth lens group decreases; and the positive second lens group, the negative third lens group and the positive fourth lens group move toward the object. The wide-angle zoom lens system satisfies the following conditions: 1.2<|f(i=1)/fW|<2.0??(1) 1.5<f(i=2)/fW<2.2??(2) 2.5<|f(i=3)/fW|<3.6??(3) 3.2<f(i=4)/fW<4.

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 camera system includes a lens unit and a camera body to which the lens unit is detachably attached. The lens unit has a photographing lens, an imaging device which receives light transmitted through the photographing lens, and a lens-side connecting terminal for electric connection. The camera body has a camera-side connecting terminal which is connectable to the lens-side connecting terminal, and a movable member which is movable between a first position that is close to the camera-side connecting terminal and a second position that is far from the camera-side connecting terminal. The camera-side connecting terminal is shut in the camera body when the movable member is in the first position, and the lens unit can be attached when the movable member is in the second position.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group. 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, and a distance between the positive second lens group and the positive third lens group increases. When zooming is being performed, the negative first lens group remains stationary, and the positive second lens group and the positive third lens group are moveable along the optical axis of the zoom lens system; and the zoom lens system satisfies the following conditions: 1.5<f3/f2<2.5 ??(1) 0.8<f2/(fw*ft)1/2<1.

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 zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group. Upon zooming from the short focal length extremity to the long focal length extremity, a distance between the first lens group and the second lens group decreases, and a distance between the second lens group and the third lens group increases. When zooming is being performed, the third lens group remains stationary, and the first lens group and the second lens group are moveable along the optical axis of the zoom lens system; and the zoom lens system satisfies the following conditions: 3.0<f3/f2<3.5??(1) 1.4<|f1/fW|<2.0??(2) 0.8<f2/fW<1.5??(3) wherein f1 designates the focal length of the first lens group; f2 designates the focal length of the second lens group; f3 designates the focal length of the third lens group; and fw designates the focal length of the entire zoom lens system at the short focal length extremity.

Abstract: An image pickup apparatus includes a multifocal optical system having at least two different focal lengths; an image pickup device for converting an optical image formed by the multifocal optical system into an image signal; a first image processor for forming an original image defined by an object image at each focal length of the multifocal optical system with the image signal received from the image pickup device; and a second image processor for trimming the original image formed by the first image processor. An object image of an angle-of-view corresponding to an intermediate focal length between the two focal lengths of the multifocal optical system is complemented by a trimmed image formed by the second image processor.

Abstract: An image pickup apparatus includes a multifocal optical system in which first and second focal lengths on short and long focal length sides is optically selected; an image pickup device for converting an optical image into an image signal; an image processor which processes the image signal to form an original image; a trimming device for trimming the original image formed by the image processor; a drive controller for switching the optical focal length when the set angle-of-view of the trimming device changes between the second angle-of-view and a third angle-of-view which is smaller than the second angle-of-view; and a memory for storing an original image formed by the image processor at a focal length before the optical focal length is switched by the drive controller. The trimming device forms trimmed images of set angle-of-views while the optical focal length is switched.

Abstract: A wide-angle lens system includes a negative first lens group, and a positive second lens group, in this order from the object. The groups are positioned so that the distance between the negative first lens group and the positive second lens group is set as the maximum distance in the wide-angle lens system. The wide-angle lens system satisfies the following conditions: 2.0<fB/f<2.5??(1) 4.5<f1/f<6.2??(2) 1.8<f2/f<2.0??(3) 1.0<d/f<1.5??(4) wherein fB: the back focal distance of the wide-angle lens system; f: the entire focal length of the wide-angle lens; f1: the focal length of the negative first lens group; f2: the focal length of the positive second lens group; and d: the axial distance between the negative first lens group and the positive second lens group.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group. 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, and a distance between the positive second lens group and the positive third lens group increases. When zooming is being performed, the negative first lens group remains stationary, and the positive second lens group and the positive third lens group are moveable along the optical axis of the zoom lens system; and the zoom lens system satisfies the following conditions: 1.5<f3/f2<2.5 ??(1) 0.8<f2/(fw*ft)1/2<1.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group. Upon zooming from the short focal length extremity to the long focal length extremity, a distance between the first lens group and the second lens group decreases, and a distance between the second lens group and the third lens group increases. When zooming is being performed, the third lens group remains stationary, and the first lens group and the second lens group are moveable along the optical axis of the zoom lens system; and the zoom lens system satisfies the following conditions: 3.0<f3/f2<3.5??(1) 1.4<|f1/fW|<2.0??(2) 0.8<f2/fW<1.5??(3) wherein f1 designates the focal length of the first lens group; f2 designates the focal length of the second lens group; f3 designates the focal length of the third lens group; and fW designates the focal length of the entire 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. Upon zooming from the short focal length extremity to the long focal length extremity, the distance between the negative first lens group and the positive second lens group decreases, the distance between the positive second lens group and the negative third lens group increases, and the distance between the negative third lens group and the positive fourth lens group decreases; and the positive second lens group, the negative third lens group and the positive fourth lens group move toward the object.

Abstract: A wide-angle lens system includes a negative first lens group, and a positive second lens group, in this order from the object. The negative first lens group and the positive second lens group are positioned so that the distance between the negative first lens group and the positive second lens group is set as the maximum distance in the wide-angle lens system.