Abstract: A zoom optical system with a vibration correction function includes, from the object side, a first lens group having positive refractive power and that is stationary during zooming, a second lens group having negative refractive power and that moves along the optical axis during zooming, a third lens group having positive refractive power that includes a stop, and a fourth lens group having positive refractive power. Two of the second, third, and fourth lens groups move along the optical axis during zooming. A fifth lens group may be included. At least part of one of the third, fourth, or fifth lens groups that does not move along the optical axis during zooming is movable in a direction that intersects the optical axis in order to correct for blurring of an image due to vibration of the zoom optical system. An imaging device uses the zoom optical system.

Abstract: A lens device having a function of varying a magnification of the lens device and a function of focusing includes, in the order from an object side to an image side, a first lens unit which has a positive optical power and which is fixed during the variation of magnification, a second lens unit which has a negative optical power and which moves during the variation of magnification, and a third lens unit which has a positive optical power and which is fixed during the variation of magnification. The third lens unit includes a first lens sub-unit which is fixed during focusing, a second lens sub-unit which has a positive optical power and which moves during focusing, and a third lens sub-unit which has a positive optical power and which is fixed during focusing, in that order from the object side to the image side.

Abstract: A zoom lens includes first to fourth lens units arranged in order from an object, respectively. The first lens unit is fixed during power-varying and has positive optical power. The second lens unit is movable during power-varying. The third lens unit is movable so as to compensate image-plane fluctuation in accordance with the power-varying. The fourth lens unit is fixed during the power-varying and has positive optical power. The first lens unit includes a first lens subunit having positive optical power, and a second lens subunit having negative optical power, arranged in order from the object, respectively. One of the first and second lens subunits moves upon focus adjustment. Further, the following conditions are satisfied: ?2.5<f1b/f1a<?0.6 and 0.2<f1/fT<0.8. Wherein f1, f1a, f1b, and fT respectively represent the focal lengths of the first lens unit, the first lens subunit, the second lens subunit, and the overall system of the zoom lens at its telephoto end.

Abstract: A zoom lens includes a first lens band having a positive focal length, a second lens band having a negative focal length, and at least third to fifth lens bands having positive focal lengths. An aperture diaphragm is located in the vicinity of the third lens band. When magnification i.e., zooming is performed from short to long focal point ends, the second lens band smoothly moves toward the third lens band and the fourth lens band simultaneously moves from the fifth lens band side toward a long focal point end so as to share a magnification function together with the second lens band.

Abstract: An objective has a front group, a focus group displaceable along the optical axis and a follow-on lens group having a diaphragm. The front group is arranged at the objective end. The lens group having the diaphragm includes at least two composite lenses and/or two positive lenses and/or the back focus can be adjusted. An objective series is presented wherein all objectives of the series have a uniform appearance and/or the diaphragm is arranged in all objectives proceeding from the image plane at the same location.

Abstract: A zoom lens according to the present invention includes, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a negative refractive power, and a fourth lens unit having a positive refractive power. During a magnification change from the wide-angle end through the telephoto end, the first lens unit and the fourth lens unit shift from the image-surface side toward the object side, a space between the first lens unit and the second lens unit increases, and spaces between individual lens units change. During a focusing from an object at the infinite distance onto an object at a near distance, the second lens unit and the third lens unit individually shift independently.

Abstract: A zoom lens capable of correcting camera shake and being reduced in size and weight, comprising five groups of lenses respectively having positive, negative, positive, negative, positive refractive powers, the second lens group (12) varying power, the fifth lens group (15) adjusting focusing. The third lens group (13) is moved in a direction perpendicular to the optical axis when correcting camera shake. When lens power on the object side of a cemented lens in the first lens group (11) is ?11, lens power on the image plane side ?12, the Abbe number of a lens on the object side ?d11, and the Abbe number of a lens on the image plane side ?d12, the condition of the following Expression 82 is satisfied: ?75<?d11?d12(?11+?12)/(?11?d12+?12?d11)<?50.Expression 82.

Abstract: A zoom lens, having a camera shake correction function, that is capable of preventing degradation of chromatic aberration while correcting camera shake, and can be small, light-weight and power-saving, is provided. The zoom lens is composed of four groups of lenses having positive, negative, positive and positive refractive powers, arranged in that order from an object side to an image plane side, where a second lens group conducts zooming and a fourth lens group conducts focus adjustment. The second lens group is made of a concave meniscus lens, a concave lens, a double convex lens, and a concave lens, arranged in that order from the object side to the image plane side, and it includes also at least one aspheric surface. A third lens group includes a cemented lens having a cemented surface whose convex surface faces the object side, and can be shifted in a perpendicular direction with respect to an optical axis in order to correct image fluctuations during a camera shake.

Abstract: There is disclosed a zoom lens having small variations of aberration and field angle during focusing and having a small system as a whole. The zoom lens includes a first lens unit having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a negative optical power, a fourth lens unit having a positive optical power, and a fifth lens unit having a positive optical power, in order from an object side to an image side. During zooming, the second lens unit and third lens unit are moved, and during focusing, the fifth lens unit is moved. The fifth lens unit consists of one negative lens element and two positive lens elements in order from the object side to the image side, and the following conditions are satisfied: 0<?5<0.35 1.85<?5p/?5n.

Abstract: A rear focus zoom lens is disclosed that includes, in order from the object side: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power and including a stop; a fourth lens group having negative refractive power; and a fifth lens group having positive refractive power. The second lens group and the third lens group are moved along the optical axis for zooming, the fourth lens group is moved along the optical axis for focusing, and the fourth lens group comprises a doublet consisting of a negative lens element and a positive lens element. The fifth lens group may have a specified configuration which includes an aspherical surface and that satisfies a specified condition which insures that aberrations are satisfactorily corrected over the entire range of zoom.

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. Upon zooming, the second lens group moves from the object side to the image side, and the fourth lens group moves in order to compensate the move of the image plane. The fourth lens group includes sub-lens groups, wherein a first sub-lens group satisfies specific conditions. The first sub-lens group has an aspherical surface on at least the object-side surface thereof. The aspherical surface is formed so that the higher a height from the optical axis in a radial direction becomes the weaker the refractive power is, compared with a paraxial spherical surface.

Abstract: A zoom lens system includes a movable positive first lens group, a movable negative second lens group, a movable positive third lens group, and movable stationary or positive fourth lens group. Upon zooming, the distance between the first and second lens groups is increased; the distance between the second and the third lens groups is decreased; and the distance between the third and the fourth lens groups is increased.

Abstract: A zoom lens has an easily bendable optical path with high optical specification performance such as a high zoom ratio, a wide-angle arrangement, a small F-number and reduced aberrations. The lens comprises a first lens group GI that remains fixed during zooming, a second lens group G2 that has negative refracting power and moves during zooming, a third lens group G3 that has positive refracting power and moves during zooming, and a fourth lens group G4 that has positive refracting power and moves during zooming and focusing. The first lens group comprises, in order from an object side thereof, a negative meniscus lens component convex on an object side thereof, a reflecting optical element for bending an optical path and a positive lens. The fourth lens group G4 moves in a locus opposite to that of movement of the third lens group G3 during zooming when focusing on infinity.

Abstract: The zoom lens has, in order from the object to image sides, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens unit having a positive refractive power, wherein the second lens unit and the fourth lens unit move during zooming. The following condition is satisfied: ?23<20.0, N23>1.9, ?1.0<f2/f2t<?0.05, where f2 represents a focal length of the second lens unit, ft represents a focal length of the entire system at a telephoto end zoom position, and ?23 and N23 represent an Abbe number and a refractive index of the material forming the third lens of the second lens unit, respectively.

Abstract: A zoom lens system has four lens units, i.e., in order from an object side to an image side, a first lens unit of negative optical power, a second lens unit of positive optical power, a third lens unit of positive optical power, and a fourth lens unit of positive optical power. During zooming from a wide-angle end to a telephoto end, a space between the first lens unit and the second lens unit decreases, a space between the second lens unit and the third lens unit varies, and a space between the third lens unit and the fourth lens unit increases. Two negative lens elements constituting the first lens unit are made from high refractive index materials. Accordingly, a small-sized zoom lens system capable of obtaining a desired wide angle of field at the wide-angle end, a desired zoom ratio and high optical performance with a minimum number of lens elements can be provided.

Abstract: A zoom lens includes in order from the object side to the image side, a first lens unit of negative optical power and a second lens unit of positive optical power. Zooming is effected by varying the interval between the first lens unit and the second lens unit. The second lens unit has, in order from the object side to the image side, an aspherical positive lens and an aspherical negative lens.

Abstract: The invention relates to a high-performance, large-aperture yet wide-angle zoom lens system that can be used with an electronic image pickup device in particular, a method for focusing the same. In particular, the invention is concerned with a high-performance, large-aperture yet wide-angle zoom lens system which has a zoom ratio of the order of 3 at a diagonal field angle of 75° at its wide-angle end, so that it can be used with a single-lens reflex camera using an electronic image pickup device with the number of pixels being of the order of 6,000,000. The zoom lens system comprises a first lens group G1 having negative refracting power, a second lens group G2 having positive refracting power, a third lens group G3 having negative refracting power, a fourth lens group G4 having positive refracting power and a fifth lens group G5 having positive refracting power. Upon movement of an object point, focusing is carried out with the fifth lens group G5.

Abstract: A three-group zoom lens includes first, second, and third lens groups, of negative, positive, and positive or negative refractive power, respectively. The second lens group includes a stop and the third lens group moves for focusing. When zooming from the wide-angle end to the telephoto end, the first and second lens groups become closer together. The zoom lens preferably satisfies specified conditions that ensure compactness, ease of manufacture, and favorable correction of aberrations. The zoom lens includes aspheric lens elements with lens surfaces defined by an aspheric lens equation that: (a) includes at least one non-zero coefficient of an even power of Y, and at least one non-zero coefficient of an odd power of Y, where Y is the distance of a point on the aspheric lens surface from the optical axis, and/or (b) includes at least one non-zero coefficient of Yi, where i is even and 16 or greater.

Abstract: An object of the present invention is to provide a super wide-angle zoom lens system having an angle of view of 2?=100° or more, a zoom ratio of about 2, the f-number of about f/4, sufficient amount of peripheral light quantity, high optical performance, and aspherical surfaces capable of being manufactured easily. According to one aspect of the present invention, in order from an object, a first lens group G1 having negative refractive power, and a second lens group G2 having positive refractive power are provided. Zooming is carried out by varying a distance between the first lens group G1 and the second lens group G2. The first lens group G1 has a negative lens component Ln and a positive lens component Lp. The negative lens component Ln has at least one aspherical lens Lasp. The aspherical lens Lasp satisfies given conditional expressions.

Abstract: The invention provides a zoom lens system much more reduced in size and cost than ever before and best-suited for use on portable information terminals of small size. The zoom lens system comprises, in order from an object side thereof, a first lens group G1 having positive refracting power and designed to be fixed during zooming, a second lens group G2 having negative refracting power and designed to move from the object side to an image plane side of the system for zooming from a wide-angle end to a telephoto end of the system, a third lens group having refracting power and designed to move from the image plane side to the object side for zooming from the wide-angle end to the telephoto end, and a fourth lens group G4 having positive refracting power and designed to be movable during zooming.

Abstract: A zoom lens device has a zoom lens system having a plurality of lens units; and an image sensor converting an optical image formed by the zoom lens system, into electric image data. The zoom lens system has a first lens unit disposed on the most object side and consisting of a single negative lens element, a second lens unit having a positive optical power; and a diaphragm disposed on the object or the image side of the second lens unit, or in the second lens unit. Zooming is performed by varying the distances between the lens units. Focus adjustment by varying the object distance is performed by moving along the optical axis a positive lens unit or a single lens element disposed in a position on the image side of the diaphragm and not included in the most image side lens unit.

Abstract: A telephoto lens includes, in order from the object side, a first lens unit having a positive refracting power, a second lens unit having a negative refracting power, a third lens unit having a positive refracting power, and a fourth lens unit having a negative refracting power. The second lens unit has a cemented lens composed of a positive lens and a negative lens, and a negative lens. The fourth lens unit has a cemented lens composed of a negative lens and a positive lens, and a negative lens. The telephoto lens satisfies the following conditions: ?d>80 ?0.5>f4/f>?1.2 where ?d is an Abbe's number of a lens having a positive refracting power in the first lens unit, f4 is a focal length of the fourth lens unit, and f is a focal length of the entire optical system.

Abstract: A zoom lens comprising, disposed in order from an object side to an image surface side, a negative-power first lens group, a diaphragm, a positive-power second lens group, and a positive power third lens group, characterized in that, when zooming from a wide-angle end to a telelscope end, an air gap between the first lens group and the second lens group shrinks and an air gap between the second lens group and the third lens group expands, the third lens group is movable in an optical axis direction for focusing, and a zoom ratio at a shooting distance of ? is 2.5- to 3.2-magnification.

Abstract: The invention provides a zoom lens device that can include lens groups. A third lens group (compensator lens group) can be disposed between two lens groups (a second and a fourth lens groups) forming a variator lens group. The two lens groups (the second and fourth lens groups) forming the variator lens group can be retained by a common variator-lens frame and moved together. Accordingly, a zoom lens device, an optical apparatus, and a projector can be provided in which, even when a plurality of lens groups are assembled, degradation of optical characteristics due to decentering between the lens groups can be prevented.

Abstract: A zoom lens to form an image of an object with variable magnification between a shortest focal length and a longest focal length, is provided with a first lens group having a positive refracting power; a second lens group positioned closer to the image than the first lens group and having a negative refracting power; and a third lens group positioned closer to the image than the second lens group and having a positive refracting power. When the magnification is changed from the shortest focal length to the longest focal length, the third lens group is shifted toward the object and the first lens group and the second lens group are shifted in such a manner that a distance between the first lens group and the second lens group is increased and a distance between the second group and the third group is decreased. The third lens group comprises at least a single positive lens and at least a single negative lens. A variable magnification ratio of the zoom lens is four times or more.

Abstract: This specification discloses a zoom lens having good optical performance over the whole of an object distance from an infinity object to a super-close range object. This zoom lens system comprises, in order from the front to the rear, a first lens unit of positive optical power, a second lens unit of negative optical power, and a following lens component of positive optical power as a whole. During zooming, the first lens unit moves so that the interval between the first lens unit and the second lens unit may become great at the telephoto end relative to the wide angle end. At least one lens unit moves for focusing resulting from a change in an object distance, and the lens unit moving for the focusing is provided with a diffractive optical surface.

Abstract: A zoom lens system includes a movable-positive first lens group, a movable-negative second lens group, a movable-positive third lens group, and a movable-positive fourth lens group. Upon zooming from the short to the long focal length extremities, all the lens groups are arranged to move in a manner that the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, the distance between the third lens group and the fourth lens group increases, and the distance between the first lens group and the third lens group does not change. Upon zooming from the short to the long focal length extremities, the fourth lens group first moves toward the image and thereafter moves toward the object in a U-turn path.

Abstract: The pickup lens (1) employing the present invention includes a first lens group (11) having negative power, a diaphragm (12), a second lens group (13) having positive power, and a third lens group (14) having negative power, which are arranged in this order from the side of a subject. When varying optical power, in the pickup lens (1), the first lens group (11) is fixed, and the second lens group (13) is moved along the optical axis together with the diaphragm (12), and the third lens group (14) is moved along the optical axis to correct movement of the image point due to variation of optical power.

Abstract: A rear-focus zoom lens device includes a wide-angle direction rotation restricting unit and a telephoto direction rotation restricting unit for separately restricting rotations of a zoom ring in a wide-angle direction and a telephoto direction and for separately canceling the restricting operations at any rotational positions of the zoom ring in the wide-angle direction and the telephoto direction, respectively, when rotating the zoom ring in the wide-angle direction and the telephoto direction, respectively.

Abstract: A zoom lens system according to the invention includes, in order from the front to the rear, a first lens unit having negative optical power, an aperture stop, a second lens unit having positive optical power, and a third lens unit having positive optical power, and the distance between the first lens unit and the second lens unit varies when zooming. The second lens unit consists of, in order from the front to the rear, a positive lens element and a negative lens element disposed at a distance therefrom. The distances between the second lens unit and the third lens unit at the short focal length end and at the long focal length end are set to suitable values. Consequently, a zoom lens system having a superior optical performance is achieved without increasing the number of lenses included therein.

Abstract: A zoom lens capable of correcting camera shake and being reduced in size and weight, comprising five groups of lenses respectively having positive, negative, positive, negative, positive refractive powers, the second lens group (12) varying power, the fifth lens group (15) adjusting focusing. The third lens group (13) is moved in a direction perpendicular to the optical axis when correcting camera shake.

Abstract: The invention relates to a zoom lens system which is compatible with a TTL optical finder having a diagonal field angle of at least 70° at the wide-angle end and about 7 to 10 magnifications and is fast as represented by an F-number of about 2.8 at the wide-angle end. The zoom lens system comprises a first lens group G1 which is movable along its optical axis during zooming and has positive refracting power, a second lens group G2 which moves toward the image side along the optical axis during zooming from the wide-angle end to the telephoto end and has negative refracting power and rear lens groups G3 to G6 having at least two spacings variable during zooming. In particular, the focal length f1 of the first lens group G1 should meet 6<f1/L<20 where L is the diagonal length of an effective image pickup surface I located in the vicinity of an image-formation plane.

Abstract: A rear focus zoom lens is disclosed that includes, in order from the object side: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power and including a stop; a fourth lens group having negative refractive power; and a fifth lens group having positive refractive power. The second lens group and the third lens group are moved along the optical axis for zooming, the fourth lens group is moved along the optical axis for focusing, and the fourth lens group comprises a doublet consisting of a negative lens element and a positive lens element. The fifth lens group may have a specified configuration which includes an aspherical surface and that satisfies a specified condition which insures that aberrations are satisfactorily corrected over the entire range of zoom.

Abstract: This invention provides a zoom lens system with, in succession from the front to rear, a first lens unit of negative optical power, a second lens unit of positive optical power and a third lens unit of positive optical power. When zooming from a short focal length end to a long focal length end, the second lens unit moves forward, while the third lens unit moves along a locus that is located rearmostly at other zoom position than the short focal length end and that is convex toward the image side or a part of it. The first lens unit does not move. Further, the first lens unit has a negative lens with a concave rear surface, and a positive lens with a convex front surface. The second lens unit has a negative lens with a concave rear surface, and a positive lens disposed rearwardly of the negative lens.

Abstract: The invention is dedicated to a compact and lightweight high zoom ratio lens which is configured in 4 lens group zoom system with a deployment of positive, negative, positive, and positive refraction lens groups in order, being approximately 75 degree in shooting angle of view at a wide-angle end, approximately f/3 to 4 at the wide-angle end, and approximately f/6 to 7 at a telephoto end so as to implement an enhanced variable zoom power up to approximately 10. The zoom lens includes first to fourth lens groups each comprised of a plurality of lenses, the lens groups having respective refractive indices of positive, negative, positive, and positive levels in order from the closest to an object.

Abstract: An electronic picture taking apparatus comprises a zoom lens system and an image pickup device. The zoom lens system has a type of movement suitable for stable, high performance in the range from infinite to near distance and having a reduced thickness. The zoom lens system comprises at least four lens units. A foremost first lens unit on the object side of said zoom lens system has a negative refractive power. Each of three consecutive lens units has variable space on the image side thereof between an adjacent lens unit for performing a zooming operation. A rearmost lens unit of the zoom lens system consists of a single positive lens element having an aspherical surface and being fixed during the zooming operation. The zoom lens system includes an aperture stop moving incorporated with the second lens unit which is adjacent to the first lens unit.

Abstract: A three-group zoom lens includes, in order from the object side, a first lens group of negative refractive power, and second and third lens groups, each of positive refractive power. The first and second lens groups include negative and positive components and the third lens group is a single lens component. All but one lens component may be a single lens element. When zooming from the wide-angle end to the telephoto end, the first and second lens groups move closer together while the second lens group moves farther from the third lens group. The third lens group remains stationary during zooming but moves for focusing. The second lens group includes a diaphragm on its object side. Aspheric lens surfaces are disclosed. The zoom lens satisfies certain conditions for the focal lengths of the zoom lens and a component of the zoom lens, and for Abbe numbers of two lens elements.

Abstract: A zoom optical system has a focus adjusting unit that performs focusing for an object by moving along an optical axis thereof and a magnification adjusting unit that corrects a change in optical magnification caused by the focusing by moving along an optical axis thereof.

Abstract: A zoom lens system includes a positive first lens group, a negative second lens group, and a positive third lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, the positive first lens group remains stationary, the negative second lens group moves toward the image, and the positive third lens group moves toward the object. The positive first lens group includes a first sub-lens group which is stationary and a second sub-lens group which functions as a focusing lens group.

Abstract: A 10× ratio wide-angle zoom lens includes several lens sets which is made of several lenses with different focal lengths. It has a first lens set with a positive dioptre, a second lens set with a negative dioptre, a third lens set with a positive dioptre, and a fourth lens set with a positive dioptre. The second lens set further contains two lenses with negative dioptres and one lens with a positive dioptre. The lens with a positive dioptre has a non-spherical surface on the object side. The lens with a negative dioptre closer to the lens with a positive dioptre is cemented to the positive-dioptre lens. The fourth lens set contains a lens with a negative dioptre and two non-spherical surfaces. The wide-angle zoom lens moves the second and the fourth lens set along its optical axis to adjust its zoom and moves the fourth lens set to focus.

Abstract: Disclosed is a zoom lens system which uses a diffractive optical element such that high optical performance can be obtained over the overall power variation range. The zoom lens system includes a first lens unit having positive optical power, and a second lens unit having negative optical power and disposed on a rearward side of the first lens unit. A diffractive optical portion is provided on a cemented surface, which is convex toward a forward side, in the first lens unit or the second lens unit.

Abstract: A zoom lens system, with a new structure that exhibits high optical performance over the entirety of a zoom range and the entirety of a focusing range, is disclosed. This zoom lens system comprises, in order from an object side to an image side: a front lens group which includes a plurality of lens units that move during zooming; a lens unit with negative optical power which moves during zooming and moves towards the object side during focusing from an infinity object to a close-distance object; and a lens unit with positive optical power which does not move for zooming.

Abstract: A compact yet low-cost zoom lens system being particularly suited for use with small portable information terminal equipment is provided. The zoom lens system includes, in order from an object side thereof, a first, third and fourth lens groups G1, G3 and G4 that have positive refracting powers and a second lens group G2 that has negative refracting power. Lens group G1 remains fixed during zooming and lens groups G2 and G3 move during zooming and lens group G4 is movable during zooming. In one embodiment, the zoom lens system includes a negative lens located nearest to the imaging side of the second lens group G2 that satisfies condition (7).

Abstract: A zoom lens is disclosed having four groups of positive, negative, positive, and positive refractive power, respectively, in order from the object side. The second lens group includes, in order from the object side, a biconcave or plano-concave lens, a biconcave lens, and a positive meniscus lens with its convex surface on the object side. The third lens group is a single lens having at least one surface that is aspherical. The fourth lens group includes a biconvex lens positioned between two meniscus lenses, and includes at least one surface that is aspherical. The first and third lens groups are fixed in position, the second lens group moves for zooming, and the fourth lens group moves for both zooming and focusing. A specified condition is satisfied to provide a zoom lens of small overall length, a zoom ratio that exceeds 6, a wide-angle of view, and favorably corrected aberrations.

Abstract: A zoom lens system includes a positive first lens group, a positive second lens group, and a negative third lens group. Upon zooming from the short toward the long focal length extremities, the three lens groups are moved independently along the optical axis so that 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 and the second lens group which are independently moved upon zooming are integrally moved upon focusing.

Abstract: A lens barrel having a zoom lens system including a plurality of variable power lens groups which includes a switching lens group having two sub-lens groups which are optically operable in mutually close and distant positions, the lens barrel includes a first sub-lens group frame for supporting one sub-lens group; a second sub-lens group frame for supporting the other sub-lens group; a switching lens group frame for supporting the first and second sub-lens group frames; a shift mechanism for selectively moving the first and second sub-lens group frames in the switching lens group frame to the mutually close and distant positions; and a switching lens group frame moving mechanism for moving the switching lens group frame with the other variable power lens group(s) along a predetermined path to vary the focal length; wherein combined movement of the shift mechanism and the switching lens group frame moving mechanism provides a zoom path for the sub-lens groups.

Abstract: A optical device has a zoom lens system that is comprised of a plurality of lens units and that achieves zooming by varying unit-to-unit distances and an image sensor that converts an optical image formed by the zoom lens system into an electrical signal. The zoom lens system is comprised of, from the object side, a first lens unit having a negative 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. The zoom lens system achieves zooming by varying the distances between the first to fourth lens units.

Abstract: A zoom lens having five lens groups arranged in succession. The zoom lens is configured such that when zooming from a short focal length end toward a long focal length end, the second lens group lens moves toward the third lens group and the fourth lens group moves toward a side of the third lens group, and the fifth lens group corrects the zooming and a shift in a position of an imaging plane of the zoom lens caused by movement of the third lens group and the fourth lens group.

Abstract: The invention provides a zoom lens system much more reduced in size and cost than ever before and best-suited for use on portable information terminals of small size. The zoom lens system comprises, in order from an object side thereof, a first lens group G1 having positive refracting power and designed to be fixed during zooming, a second lens group G2 having negative refracting power and designed to move from the object side to an image plane side of the system for zooming from a wide-angle end to a telephoto end of the system, a third lens group having refracting power and designed to move from the image plane side to the object side for zooming from the wide-angle end to the telephoto end, and a fourth lens group G4 having positive refracting power and designed to be movable during zooming.

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 negative fourth lens group. Zooming is performed by moving each of the lens groups along the optical axis.