Abstract: An imaging device is provided with an imaging sensor having a rectangular imaging surface, an image-forming optical system for forming an image onto the imaging surface, and a prism disposed between the image-forming optical system and the imaging sensor for bending an optical path. A mask, having a rectangular opening, limits light that is to be incident on the imaging sensor. The aspect ratio (long side/short side) of the mask rectangular opening of the mask is larger than that of the rectangular imaging surface, and the peripheral light quantity difference between the short and long sides on the rectangular imaging surface is smaller than in the case of these two aspect ratios being equal to each other.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group, in that order from the object side. The second lens group constitutes a focusing lens group. The following conditions (1) and (2) are satisfied: 0.4<|d12w/f1|<1.06??(1); and d12w<d23w??(2), wherein f1 designates the focal length of the first lens group, and d12w and d23w designate the air distances between the first and second lens groups, and the second and third lens groups respectively, at the short focal length extremity.

Abstract: A 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 an object. Upon zooming from the short focal length extremity to the long focal length extremity, the distance between the first and the second lens groups increases, and the distance between the second and the third lens groups decreases. The third lens group includes a positive first sub-lens group and a negative second sub-lens group, in this order from the object. The first sub-lens group comprises a positive lens element provided at the most object-side thereof and a cemented lens provided at the most image-side thereof. The cemented lens includes a positive lens element and a negative lens element, in this order from the object.

Abstract: A zoom lens system includes a positive first lens group, a negative second lens group, and positive third and fourth lens groups. Upon zooming from the short to long focal length extremities, the distance between the first and second lens groups increases and the distance between the second and third lens groups decreases. The first lens group includes a positive first sub-lens group which remains at a stationary position during focusing and a positive second sub-lens group which moves during focusing. Condition (1) is satisfied: 0.35<f1b/f1a<0.57??(1), wherein f1b and f1a designate the focal length of the second and first sub-lens groups, respectively.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a negative third lens group, in that order from the object side, wherein upon zooming from the short focal length extremity to the long focal length extremity, the distance between the first lens group and the second lens group decreases, wherein the following condition (1) is satisfied: ?2.45<f1/f2<?2.05??(1), wherein f1 designates the focal length of the first lens group, and f2 designates the focal length of the second lens group.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a negative third lens group, in that order from the object side, wherein upon zooming from the short focal length extremity to the long focal length extremity, the distance between the first lens group and the second lens group decreases. The third lens group includes a negative lens element having a concave surface on the image side, a positive lens element having a convex surface on the image side, and a negative lens element having convex surface on the image side, in that order from the object side. An electronic imaging apparatus using this zoom lens system is also disclosed.

Abstract: An imaging device is provided with an imaging sensor having a rectangular imaging surface, an image-forming optical system for forming an image onto the imaging surface, and a prism disposed between the image-forming optical system and the imaging sensor for bending an optical path. A mask, having a rectangular opening, limits light that is to be incident on the imaging sensor. The aspect ratio (long side/short side) of the mask rectangular opening of the mask is larger than that of the rectangular imaging surface, and the peripheral light quantity difference between the short and long sides on the rectangular imaging surface is smaller than in the case of these two aspect ratios being equal to each other.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group, in that order from the object side. Upon zooming from the short to long focal length extremities, the first through third lens groups move along an optical axis direction so that the distance between the first and second lens groups decreases, and the distance between the second and third lens groups increases. The first lens group includes a negative glass lens element and at least two plastic lens elements, in that order from the object side, and wherein the following condition (1) is satisfied: |f1/f1pc|<0.04 . . . (1), wherein f1 designates the focal length of the first lens group, and f1pc designates the combined focal length of the plastic lens elements that are provided within the first lens group.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group, in that order from the object side. Upon zooming from the short to long focal length extremities, the first through third lens groups move along an optical axis direction so that the distance between the first and second lens groups decreases, and the distance between the second and third lens groups increases. The second lens group includes a positive glass lens element and at least two plastic lens elements, in that order from the object side, and wherein the following condition (1) is satisfied: ?0.25<f2/f2pc<?0.05 . . . (1), wherein f2 designates the focal length of the second lens group, and f2pc designates the combined focal length of the plastic lens elements that are provided within the second lens group.

Abstract: A retrofocus wide-angle lens system is provided, wherein the entire the wide-angle lens system is divided at a position that satisfies the following condition (1) between a theoretical front lens group having a negative refractive power, and a theoretical rear lens group having a positive refractive power including the diaphragm, at a minimum focal length, and wherein a flat parallel plate is disposed at the position that satisfies the following condition (1): 1.2<|fF/f|<4.0??(1), wherein fF designates the focal length of the theoretical front lens group having a negative refractive power, and f designates the focal length of the entire the wide-angle lens system.

Abstract: A high zoom-ratio zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group, a negative fourth lens group, a positive fifth lens group, and a negative sixth lens group, in this order from an 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, and a distance between the negative second lens group and the positive third lens group decreases. The high zoom-ratio zoom lens system satisfies the following conditions: 5.0<f1/|f2|<9.0(f2<0)??(1) 4.1<f1/f5<6.0??(2) wherein f1 designate the focal length of the positive first lens group; f2 designate the focal length of the negative second lens group; and f5 designate the focal length of the positive fifth lens group.

Abstract: A high zoom-ratio 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 an object, wherein upon zooming from the short focal length extremity to the long focal length extremity, the distance between the first and the second lens groups increases, and the distance between the second and the third lens groups decreases; wherein the third lens group includes a positive first sub-lens group and a negative second sub-lens group, in this order from the object; wherein the first sub-lens group comprises a positive lens element provided at the most object-side thereof and a cemented lens provided at the most image-side thereof; wherein the cemented lens includes a positive lens element and a negative lens element, in this order from the object; and wherein the high zoom-ratio zoom lens system satisfies the following conditions: 0.3<f3a/f31<0.6 ?0.15<f3a/f3PN<0.

Abstract: A high zoom-ratio zoom lens system of five lens groups includes a positive first lens group, a negative second lens group, a positive third lens group, a positive fourth lens group, and a negative fifth 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 first lens group and the second lens group increases, and a distance between the second lens group and the third lens group decreases. The high zoom-ratio zoom lens system satisfies the following conditions: 5.5<f1/|f2|<10.0(f2<0)??(1) 1.7<f3/f4<4.0??(2) 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 f4 designates the focal length of the fourth lens group.

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 high zoom-ratio zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group, a negative fourth lens group, a positive fifth lens group, and a negative sixth lens group, in this order from an 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, and a distance between the negative second lens group and the positive third lens group decreases. The high zoom-ratio zoom lens system satisfies the following conditions: 5.0<f1/|f2|<9.0(f2<0)??(1) 4.1<f1/f5<6.0??(2) wherein f1 designate the focal length of the positive first lens group; f2 designate the focal length of the negative second lens group; and f5 designate the focal length of the positive fifth lens group.

Abstract: A high zoom-ratio zoom lens system of five lens groups includes a positive first lens group, a negative second lens group, a positive third lens group, a positive fourth lens group, and a negative fifth 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 first lens group and the second lens group increases, and a distance between the second lens group and the third lens group decreases. The high zoom-ratio zoom lens system satisfies the following conditions: 5.5<f1/|f2|<10.0(f2<0) ??(1) 1.7<f3/f4<4.0 ??(2) 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 f4 designates the focal length of the fourth lens group.

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 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: 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: 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.