Abstract: An image pickup optical system according to the present invention includes: a first lens group having a positive power; a second lens group having a negative power; a third lens group having a positive power; and a fourth lens group having a positive power which consists of a front group with a negative power and a rear group with a positive power. The first lens group moves to the object side and a distance between each neighboring lens groups changes, for varying power of the image pickup optical system. One group of the front group and the rear group in the fourth lens group consists of one lens which moves substantially perpendicular to an optical axis for a shake compensation. The image pickup optical system fulfills the predetermined conditional formula according to a focal length of the first lens group.

Abstract: A variable magnification optical system for forming an optical image of an object on a light-receiving surface of an image sensor with variable magnification includes: from the object side, at least a first lens unit having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a positive optical power, and a fourth lens unit having a positive optical power. In magnification variation from the wide angle end to the telephoto end, at least the first lens unit moves. Conditional formulae (1) and (2) below are fulfilled: (1) 6.0<fl/fw<20.0 and (2) 1.83<Ndave, where fl represents the focal length of the first lens unit, fw represents the focal length of the entire system at the wide angle end, and Ndave represents the average refractive index for a d-line among all lens elements included in the second lens unit.

Abstract: An image pickup optical system according to the present invention is provided for forming a light flux from an object into an optical image on an image pickup element. The image pickup optical system includes: a first lens group having a positive power; a second lens group having a negative power; a third lens group having a positive power; a fourth lens group having a negative power; and a fifth lens group. A distance between each neighboring lens groups changes with the fourth lens group statically positioned, for varying power of the image pickup optical system. The fourth lens group moves in a direction substantially perpendicular to an optical axis for shake compensation. The image pickup optical system fulfills the predetermined conditional formulas according to focal lengths of the first and fourth lens groups.

Abstract: An image pickup optical system according to the present invention is provided for forming a light flux from an object into an optical image on an image pickup element. The image pickup optical system includes: a first lens group having a positive power; a second lens group having a negative power; a third lens group having a positive power; a fourth lens group having a negative power; and a fifth lens group. A distance between each neighboring lens groups changes with the fourth lens group statically positioned, for varying power of the image pickup optical system. The fourth lens group moves in a direction substantially perpendicular to an optical axis for shake compensation. The image pickup optical system fulfills the predetermined conditional formulas according to focal lengths of the first and fourth lens groups.

Abstract: An image pickup optical system according to the present invention includes: a first lens group having a positive power; a second lens group having a negative power; a third lens group having a positive power; and a fourth lens group having a positive power which consists of a front group with a negative power and a rear group with a positive power. The first lens group moves to the object side and a distance between each neighboring lens groups changes, for varying power of the image pickup optical system. One group of the front group and the rear group in the fourth lens group consists of one lens which moves substantially perpendicular to an optical axis for a shake compensation. The image pickup optical system fulfills the predetermined conditional formula according to a focal length of the first lens group.

Abstract: The present invention provides a compact, high-performance, and easy-to-manufacture taking optical system that offers an extremely high zoom ratio. The taking optical system includes, from the subject side, a first lens group having a positive optical power, a second lens group having a negative optical power, a third lens group having a positive optical power, and a fourth lens group having a positive optical power. The taking optical system achieves zooming by the movements of the first to fourth lens groups and focusing by the movement of the fourth lens group. The taking optical system fulfills the following conditions: 0.05?f3/f4?0.95 and 7.0?f1/fw?20.0, where f1, f3, and f4 represent the focal lengths of the first, third, and fourth lens groups, respectively, and fw represents the focal length of the entire taking optical system at the wide-angle end thereof.

Abstract: A variable magnification optical system for forming an optical image of an object on a light-receiving surface of an image sensor with variable magnification includes: from the object side, at least a first lens unit having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a positive optical power, and a fourth lens unit having a positive optical power. In magnification variation from the wide angle end to the telephoto end, at least the first lens unit moves. Conditional formulae (1) and (2) below are fulfilled: (1) 6.0<fl/fw<20.0 and (2) 1.83<Ndave, where fl represents the focal length of the first lens unit, fw represents the focal length of the entire system at the wide angle end, and Ndave represents the average refractive index for a d-line among all lens elements included in the second lens unit.

Abstract: A taking lens system is provided with, from the side of the object to be photographed, a first lens unit (G1) having positive optical power, a second lens unit (G2) having negative optical power, a third lens unit (G3) having positive optical power and a fourth lens unit (G4) having positive optical power. Zooming is performed by moving the first to fourth lens units (G1) to (G4), and focusing is performed by moving the fourth lens unit (G4). When the distance from the most object-to-be-photographed side surface (r1) of the first lens unit (G1) to the imaging surface at the wide angle end is TLw, the overall focal length of the taking lens system at the telephoto end is ft, the overall focal length of the taking lens system at the wide angle end is fw, and the focal length of the first lens unit (G5) is fl, relationships 0.5?TLw/ft?1.0 and 6.0?fl/fw?20.0 are satisfied.

Abstract: The present invention provides a variable magnification optical system for forming an optical image of an object on the light-receiving surface of an image sensor with a variable magnification. The variable magnification optical system includes an optical construction comprising, from an object side, a first reflective surface, a first movable unit, a second reflective surface, and a second movable unit. The optical axis is bent at substantially ninety degrees by the first reflective surface and is further bent by the second reflective surface, and, during magnification variation from the wide-angle end to the telephoto end, the first and second reflective surfaces are kept in fixed positions with respect to the image surface, and the first and second movable units move along the optical axis. The variable magnification optical system fulfills a prescribed conditional formula.

Abstract: The present invention provides a compact, high-performance, and easy-to-manufacture taking optical system that offers an extremely high zoom ratio. The taking optical system includes, from the subject side, a first lens group having a positive optical power, a second lens group having a negative optical power, a third lens group having a positive optical power, and a fourth lens group having a positive optical power. The taking optical system achieves zooming by the movements of the first to fourth lens groups and focusing by the movement of the fourth lens group. The taking optical system fulfills the following conditions: 0.05?f3/f4?0.95 and 7.0?f1/fw?20.0, where f1, f3, and f4 represent the focal lengths of the first, third, and fourth lens groups, respectively, and fw represents the focal length of the entire taking optical system at the wide-angle end thereof.

Abstract: An imging lens device has a zoom lens system and an imaging sensor. The zoom lens system has a plurality of lens units and changes gaps between the lens units to thereby generate an optical image of an object which can be optically and successively zoomed in and out. The imaging sensor which converts an optical image generated by the zoom lens system into an electric signal. The zoom lens system comprises, from the object side, a first unit having a negative power, a second unit having a positive power, the second unit having a cemented lens element joining three lens elements, and a lens element having a positive power, a third unit having a positive power, and an aperture stop disposed between the first unit and the second unit. Among the three lens elements which form the cemented lens element, a lens element disposed on the object side directs a convex surface toward the object side while a lens elements disposed on the image side directs a concave surface toward the image side.

Abstract: An imging lens device has a zoom lens system and an imaging sensor. The zoom lens system has a plurality of lens units and changes gaps between the lens units to thereby generate an optical image of an object which can be optically and successively zoomed in and out. The imaging sensor which converts an optical image generated by the zoom lens system into an electric signal. The zoom lens system comprises, from the object side, a first unit having a negative power, a second unit having a positive power, the second unit having a cemented lens element joining three lens elements, and a lens element having a positive power, a third unit having a positive power, and an aperture stop disposed between the first unit and the second unit. Among the three lens elements which form the cemented lens element, a lens element disposed on the object side directs a convex surface toward the object side while a lens elements disposed on the image side directs a concave surface toward the image side.