Abstract: A projection objective includes a first lens group (G1) of positive refractive power, a second lens group (G2) of negative refractive power and at least one further lens group of positive refractive power in which a diaphragm is mounted. The first lens group (G1) includes exclusively lenses of positive refractive power. The number of lenses of positive refractive power (L101 to L103; L201, L202) of the first lens group (G1) is less than the number of lenses of positive refractive power (L116 to L119; L215 to L217) which are mounted forward of the diaphragm of the further lens group (G5).

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 variable focal length lens system includes: a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; and a fourth lens group having a positive refractive power. As the lens position state changes from a wide-angle end state to a telephoto end state, at least each of the lens groups is mobile, the second lens group moves towards the image side and the third lens group moves towards the object side such that the gap between the first and the second lens group increases, and the gap between the second and the third lens group decreases, while the fourth lens group moves in the direction of the optical axis so as to compensate for changes in the position of the image plane which accompany movements of each of the lens group.

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: A zoom lens system includes a first group G1 of positive power, a second group G2 of negative power, a third group G3 of positive power and a fourth group G4 of positive power. Upon zooming, at least the first group G1, the second group G2 and the third group G3 move on an optical axis in such a way that, at a telephoto end with respect to a wide-angle end, the space between the first group G1 and the second group G2 and the third group G3 becomes narrow and the space between the third group G3 and the fourth group G4 becomes wide. The zoom lens system satisfies a condition that defines the ratio of the total length (length from the first surface of the lens system to an image plane) to the focal length of the zoom lens system at the wide-angle end.

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: An imaging lens array that has stable performance and improved precision, wherein a first lens is a positive meniscus lens with a convex surface facing the object side; a second lens is a negative meniscus lens with a convex surface facing the object side; a third lens is a positive meniscus lens with a convex surface facing image side; and fourth lens is a positive meniscus lens with a convex surface facing the object side. When the second, third and fourth lenses are double-sided aspherical lenses, the respective lenses of the present invention can be ensured to have an appropriate power, it also can minimize error, and improve the image quality.

Abstract: An optical system comprises from the object side: a positive first lens element, a negative second lens element, a positive third lens element, a fourth lens element, and an aperture stop located between the object side of the optical system and the second lens element for controlling the brightness of the optical system. A radius of curvature R3 of a front surface of the second lens element satisfies the relation: ?0.02 [1/mm]<1/R3<0.22 [1/mm], an Abbe number V2 of the second lens element is less than 40. A focal length of the fourth lens element is f4, a focal length of the optical system is f, they satisfy the relation: f/f4<0.1, at least one inflection point is formed on the rear surface of the fourth lens element.

Abstract: To obtain a high imaging performance even for a relatively long focal length in a zoom lens provided with an optical-path bending member for bending an optical path. The following are included: a first group of lenses G1 having a positive refracting power, a second group of lenses G2 having a negative refracting power, a third group of lenses G3 having a positive refracting power, and a fourth group of lenses G4 having a positive refracting power arranged in that order from the object side to the image surface side. Zooming is performed by moving the second group of lenses G2 and fourth group of lenses G4 along an optical axis. The first group of lenses G1 is constituted of a group of positive lenses L1 having a positive refracting power and an optical-path bending member L2 for bending an optical path arranged in that order from the object side to the image face side.

Abstract: An imaging lens is provided and has, in order from the object side, a first lens of a positive lens having a convex surface on the object side thereof; a second lens in a meniscus shape having a concave surface on an image side thereof; a third lens in a meniscus shape having a convex surface on the image side thereof; and a fourth lens of a positive or negative lens, both surfaces of the fourth lens being aspheric and the fourth lens having a concave surface on the image side and in a vicinity of an optical axis of the fourth lens. The Abbe numbers of the first and second lenses as well as the focal distances of the first to fourth lenses satisfies specific conditions.

Abstract: To provide a zoom lens system with a vibration reduction having a long back focal length suitable for a digital SLR camera, a high zoom ratio, and a wide angle of view of 70° or more. The system includes, in order from the object, a first positive lens group, a second negative lens group, a third positive lens group, and a fourth positive lens group. Upon zooming from wide-angle end state to telephoto end state, a distance between the first and second lens groups increases, a distance between the second and third lens groups decreases, and a distance between the third and fourth lens groups varies. The third lens group is composed of a positive front lens group and a negative rear lens group. Image plane correction upon camera shake can be performed by shifting only the rear lens group substantially perpendicularly to the optical axis. Given conditions are satisfied.

Abstract: An object is to provide a zoom lens system having compactness, a high zoom ratio, and high optical performance with preferably correcting various aberrations. The zoom lens system includes, in order from the object, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, and a fourth lens group G4 having positive refractive power. When a state of lens group positions varies from a wide-angle end state to a telephoto end state, a distance between the first lens group G1 and the second lens group G2 increases, a distance between the second lens group G2 and the third lens group G3 decreases, a distance between the third lens group G3 and the fourth lens group G4 varies, and the fourth lens group G4 moves along a zoom trajectory having a convex shape facing to an image.

Abstract: At least one exemplary embodiment is directed to a zoom lens which includes a first lens group, which can have a positive refracting power; a second lens group, which can have a negative refracting power, and can move during zooming; a third lens group, which can have a positive refracting power; and a fourth lens group, which can have a positive refracting power, and can move during zooming, the lens groups being aligned in order from front to back, where the focal lengths fw and ft of the whole system at a wide-angle end and at a telescopic end, respectively, can satisfy the following conditions: 0.15<fw/f4 <0.26 1.0<f3/(fw·ft)1/2<1.2.

Abstract: A zoom lens system, in order from the object side to the image side, comprises 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. Magnification varying is performed by varying the distances between the lens units by moving the lens units along the optical axis. The third lens unit G3 comprises at least two lens elements including a third lens unit object side lens element which is a positive lens element disposed on the most object side and whose high-curvature surface faces the object side and a third lens unit image side lens element which is a negative lens element disposed on the most image side and concave to the image side.

Abstract: A plurality of lens units in an optical unit has at least: from the object side toward the image side, 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. When at least the first lens unit moves from the image side to the object side in zooming from the wide-angle end position to the telephoto end position, at least one gap between the lens units varies. Predetermined conditional formulae are satisfied.

Abstract: A zoom lens includes a most object-side lens unit remaining fixed on the optical axis when the magnification of the zoom lens is changed and a focusing operation is performed; a most image-side lens unit remaining fixed when the focusing operation is performed; and a plurality of moving lens units lying between the most object-side lens unit and the most image-side lens unit, moved along the optical axis when the magnification is changed. The most object-side lens unit includes, in order from the object side, a negative lens component, a reflective optical component having a reflecting surface for bending the optical path, and a positive lens component. The most image-side lens unit has at least one aspherical surface. An electronic imaging device includes an electronic image sensor located on the image side of the zoom lens.

Abstract: A zoom optical system includes a function of preventing blurring of an image due to movements, such as shaking of the zoom optical system, by moving a lens element of the third lens group, in order from the object side, of four lens groups in a direction that is perpendicular to the optical axis in order to correct for movements of the zoom optical system that would otherwise create a blurred image. The second lens group from the object side has negative refractive power and the other three lens groups have positive refractive power. The second and fourth lens groups move along the optical axis during zooming. The zoom optical system satisfies certain conditions related to the configuration of the lens elements and lens groups of the zoom optical system in order to prevent blurring and to provide a compact zoom optical system having excellent correction of aberrations.

Abstract: The invention relates to an image-formation optical system capable of achieving wide-angle arrangement and compactness at the same time and an imaging system that incorporates the same. The image-formation optical system is made up of, in order from its object side, a first positive lens L1, a second negative lens L2, a third positive lens L3 and a fourth positive lens L4. The composite focal length of the first positive lens L1 and the second negative lens L2 is positive, or the composite focal length of the second negative lens L2, the third positive lens L3 and the fourth positive lens L4 is negative.

Abstract: A hybrid lens system includes, in order from an object side to an image side: a first positive lens, a second negative lens, and a third positive lens. The first lens is made of glass material. The second and second lenses are both made of plastic material and respectively have two aspheric surfaces. The hybrid lens system is capable of resisting scraping and providing high imaging quality.

Abstract: A variable-magnification optical system has a plurality of lens groups that image a light beam from the object side on an image sensor, an optical aperture stop that intercepts part of the light beam heading for the image sensor, and a reflective mirror that changes the optical axis of the light beam of which part has been intercepted by the optical aperture stop. The plurality of lens groups include at least lens groups arranged in a positive-negative-positive-positive optical power arrangement, and at least two of the lens groups are moved for zooming from the wide-angle end to the telephoto end. The variable-magnification optical system fulfills a prescribed conditional formula.

Abstract: A zoom lens system, in order from the object side to the image side, comprises 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. Magnification varying is performed by varying the distances between the lens units by moving the lens units along the optical axis. The third lens unit G3 comprises at least two lens elements including a third lens unit object side lens element which is a positive lens element disposed on the most object side and whose high-curvature surface faces the object side and a third lens unit image side lens element which is a negative lens element disposed on the most image side and concave to the image side.

Abstract: An optical system comprises, at least, in order from an object side, a first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power, and a fourth lens group having positive refracting power, wherein at least, the second lens group and the fourth lens group move along an optical axis when magnification is changed from a wide angle end to a telephoto end, and the first lens group contains a light path reflecting element having refracting power.

Abstract: The image forming optical system includes, in order from the object side, a meniscus, a first lens having positive refracting power with a convex surface directed toward the object side, an aperture stop, a meniscus, a second lens having negative refracting power with a concave surface directed toward the object side, a third lens having positive refracting power with a convex surface directed toward the image side, and a biconvex, fourth lens having positive refracting power. The fourth lens has at least one aspherical surface and satisfies the condition: 1.0<?m/?p<50.0 where ?m and ?p represent power of the fourth lens at a position of the maximum light height and at the paraxial position, respectively. Also, the following condition is satisfied: 0.3<f1/f<2.0 where f1 and f represent the focal lengths of the first lens and of the entire image forming optical system, respectively.

Abstract: A zoom lens includes a most object-side lens unit remaining fixed on the optical axis when the magnification of the zoom lens is changed and a focusing operation is performed; a most image-side lens unit remaining fixed when the focusing operation is performed; and a plurality of moving lens units lying between the most object-side lens unit and the most image-side lens unit, moved along the optical axis when the magnification is changed. The most object-side lens unit includes, in order from the object side, a negative lens component, a reflective optical component having a reflecting surface for bending the optical path, and a positive lens component. The most image-side lens unit has at least one aspherical surface. An electronic imaging device includes an electronic image sensor located on the image side of the zoom lens.

Abstract: A lens that can be used in a digital camera includes in sequence a first lens element (20), a second lens element (30), a third lens element (40), and a fourth lens element (50). The first lens element is biconvex, and includes a first aspheric surface (22) and a second aspheric surface (24). The second lens is biconcave, and includes a third aspheric surface (32) and a fourth aspheric surface (34). The third lens element is concavo-convex, and includes a fifth aspheric surface (42) and a sixth aspheric surface (44). The fourth lens element includes a seventh aspheric surface (52) and a eighth aspheric surface (54), the seventh aspheric surface and the eighth aspheric surface being wavelike. All of the lens elements are made from plastic. The lens is light, has strong impact resistance, and provides good image quality.

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 projection objective includes a first lens group (G1) of positive refractive power, a second lens group (G2) of negative refractive power and at least one further lens group of positive refractive power in which a diaphragm is mounted. The first lens group (G1) includes exclusively lenses of positive refractive power. The number of lenses of positive refractive power (L101 to L103; L201, L202) of the first lens group (G1) is less than the number of lenses of positive refractive power (L116 to L119; L215 to L217) which are mounted forward of the diaphragm of the further lens group (G5).

Abstract: A six element fisheye objective lens comprising a first lens element having a convex object surface facing the object and a concave image surface facing the image plane, a second lens element having a convex object surface facing the object and a concave image facing the image plan. A third lens element has a positive power. A positively powered lens group has a positively powered cemented doublet lens pair. A singlet lens element has a positive power, The lens group has an object surface facing the object and an image surface facing the image. The ratio of the total track to the focal length satisfies the condition that 8<TT/fo<15. The fisheye objective lens has an optical axis, the first, second, third and the lens group being coaxially aligned on the optical axis.

Abstract: An image pickup lens includes: a first lens which is a positive lens having a positive refractive power; a second lens which is a negative lens having a negative refractive power; a third lens which is a positive lens; a fourth lens having at least one surface with an aspherical shape, wherein the first lens, the second lens, the third lens and the fourth lens are arranged from an object side of the image pickup lens in this order and the image pickup lens is designed using a predefined condition.

Abstract: A lens system has a plurality of lenses, a stop, and a diffractive surface, the entire lens system moves during focusing, and the lens system satisfies the condition of ??0.5, where ? is a maximum photographic magnification.

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 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: 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 of a novel configuration suitable for a collapsible lens barrel is disclosed. More specifically, here is disclosed a zoom lens, comprising four lens units which are, in the order from an object side toward an image side, positive, negative, positive and positive in optical power, and performing zooming by varying distances between each lens units. In this zoom lens, the fourth lens unit has a positive lens element and a negative lens element, and satisfies the following conditional expression: ?n??p where ?n is the Abbe number of the negative lens element of the fourth lens unit, and ?p is the Abbe number of the positive lens element of the fourth lens unit.

Abstract: A lens for reading an original, comprises five lenses as a whole including two positive and two negative lenses, an aspherical surface provided on at least one surface of the five lenses, a construction of four lens groups for five lenses which include a cemented lens constructed by cementing one of the positive lenses and one of the negative lenses, an aperture stop disposed between a second and third lens groups, and the cemented lens disposed adjacent to the aperture stop.

Abstract: A single focus lens is disclosed that is formed of only four lens elements. In order from the object side, these are: a first lens element of positive refractive power and having either a concave surface or planar surface on the object side; a second lens element of weak refractive power and meniscus shape that is made of plastic with at least one surface aspheric; a third lens element which has positive refractive power and a convex surface on the image side; and a fourth lens element of weak refractive power and meniscus shape that is made of plastic with at least one surface aspheric and with its concave surface on the image side. Preferably, various conditions are satisfied in order that the single focus lens be compact and favorably correct aberrations so as to provide a high quality image.

Abstract: A high-power, four-group zoom lens is disclosed which is formed of only four lens groups, in order from the object side, a first lens group of positive refractive power, a second lens group of negative refractive power, and third lens group of negative refractive power, and a fourth lens groups of positive refractive power. The fourth lens group includes, in order from the object side, a front lens subgroup and a rear lens subgroup. The rear lens subgroup includes, in order from the object side, a lens component of positive refractive power that includes a lens element, a pair of lens elements that may form a doublet component that includes a lens element of positive refractive power, a doublet component, and a lens component of positive refractive power. Specified conditions are satisfied to minimize lateral color and curvature of field.

Abstract: In a photographic optical system disclosed in the present invention, there are provided a first focusing part for focusing while exposure is not performed on a light-sensitive surface and a second focusing part for focusing while exposure is performed on the light-sensitive surface, wherein the second focusing part correct the displacement in focal position during exposure.

Abstract: The invention relates to an image-formation optical system capable of achieving wide-angle arrangement and compactness at the same time and an imaging system that incorporates the same. The image-formation optical system is made up of, in order from its object side, a first positive lens L1, a second negative lens L2, a third positive lens L3 and a fourth positive lens L4. The composite focal length of the first positive lens L1 and the second negative lens L2 is positive, or the composite focal length of the second negative lens L2, the third positive lens L3 and the fourth positive lens L4 is negative.

Abstract: An imaging device has a zoom lens system comprising a plurality of lens units and forming an optical image of an object so as to be continuously and optically zoomable by varying a distance between the lens units; and an image sensing element converting the optical image formed by the zoom lens system into an electric signal, wherein the zoom lens system comprises from the object side: a first lens unit having positive optical power as a whole and including a reflecting surface that bends a luminous flux substantially 90 degrees; a second lens unit having negative optical power and disposed with a variable air space from the first lens unit; a third lens unit having positive optical power and disposed with a variable air space from the second lens unit; a fourth lens unit having positive optical power and disposed with a variable air space from the third lens unit; and a fifth lens unit disposed with a variable air space from the fourth lens unit, and wherein zooming is optically performed by varying the air

Abstract: This specification discloses a zoom lens of novel construction in which ghost or flare caused by the reflection between a filter member and an image pickup surface suppressed. This zoom lens is provided, in succession from the front to the rear, with a first lens unit of positive power, a second lens unit of negative power moved during zooming, a stop unit, a third lens unit of positive power, and a fourth lens unit of positive power moved during zooming. The stop unit has a stop blade forming an aperture, and a filter member for attenuating the quantity of light passing through the aperture. The filter member is so disposed as to be inclined with respect to the optical axis of the zoom lens.

Abstract: A zoom lens comprising four lens units is disclosed which achieves a high variable magnification ratio and favorable optical performance at an arbitrary zoom position. The zoom lens of the present invention includes, in order from an object side, a first lens unit having 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. During zooming from the wide angle end to the telephoto end, the spacing between the first and second lens units is increased, the spacing between the second and third lens units is decreased, the spacing between the third and fourth lens units is increased, and an aperture stop moves together with the third lens unit. In addition, specific conditions are satisfied.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit of positive refractive power, a second lens unit of negative refractive power, a third lens unit of positive refractive power and a fourth lens unit of positive refractive power, zooming from a wide-angle end to a telephoto end being effected by moving the second lens unit toward the image side, and shifting of an image plane due to zooming being compensated for by moving the fourth lens unit, wherein the second lens unit consists of four separate single lenses including three negative lenses and one positive lens, and the third lens unit has at least one positive lens both surfaces of which are aspherical.

Abstract: A single focus lens is disclosed that is formed of only four lens components, which are arranged in positive, negative, positive and relatively weak positive or negative refractive power order from the object side, with a stop arranged between the first and second lens components. The third lens component has a convex surface on its image side, and the fourth lens component has a meniscus shape, is made of plastic, includes at least one aspheric surface, and is concave on its image side. The second lens component is formed of a single lens element, and various conditions are preferably satisfied so as to provide a compact lens having a short overall length while favorably correcting various aberrations.

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 system includes, in order from an object, 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 a fourth lens group having positive refractive power. When the lens system is changed from a wide-angle end to a telephoto end, each lens group is moved to the object side such that the separation between the first lens group and the second lens group increases, the separation between the second lens group and the third lens group decreases, and the separation between the third lens group and the fourth lens group decreases. The fourth lens group is composed of four lens elements arranged, in order from the object, a first positive lens element, a first negative lens element, a second positive lens element, and a second negative lens element.

Abstract: A projection optical system according to the present invention whose image side numerical aperture is greater than or equal to 0.75, and which forms an image of a first object upon a second object using light of a predetermined wavelength less than or equal to 300 nm, comprises: a first lens group G1 of positive refractive power; a second lens group G2 of negative refractive power; a third lens group G3 of positive refractive power; and a fourth lens group G4 of positive refractive power, and: the first lens group G1, the second lens group G2, the third lens group G3 and the fourth lens group G4 are arranged in order from a side of the first object; and a distance D in mm along an optical axis between an optical surface of the fourth lens group G4 closest to the second object, and the second object, satisfies a condition of 0.1<D<5.

Abstract: A variable magnification optical system includes, in order from an object side to an image side, a first lens unit of positive refractive power, a second lens unit of negative refractive power arranged to move along an optical axis during variation of magnification, the second lens unit including, in order from the object side to the image side, a first lens (L21) of negative refractive power and of meniscus form having a concave surface facing the image side, a second lens (L22) of negative refractive power, a third lens (L23) of positive refractive power and a fourth lens (L24) of negative refractive power, a third lens unit of positive refractive power, at least a part of the third lens unit being moved in such a way as to have a component perpendicular to the optical axis to displace an image formed by the variable magnification optical system, and a fourth lens unit of positive refractive power arranged to move along the optical axis during the variation of magnification, wherein the following condition

Abstract: A zoom lens, includes, in order from an object side to an image side, a first lens unit of positive refractive power, a second lens unit of negative refractive power, a third lens unit of positive refractive power and a fourth lens unit of positive refractive power, wherein a variation of magnification from a wide-angle end to a telephoto end is effected by moving the second lens unit toward the image side, shifting of an image plane due to the variation of magnification is compensated for by moving the fourth lens unit and focusing is effected by moving the fourth lens unit, a stop being disposed on the most object side of the third lens unit, the third lens unit including a positive lens (G3F) disposed on the image side of the stop and just behind the stop and having a convex lens surface facing the object side, at least one of lens surfaces of the positive lens (G3F) being an aspheric surface, and a negative lens (G3R) of meniscus form disposed on the most image side and having a concave surface facing the

Abstract: A taking lens system has, from the object side, a front lens unit, an aperture stop, and a rear lens unit. The front lens unit is composed of two lens elements that are, from the object side, a positive glass element and a negative plastic lens element. The rear lens unit has a positive plastic lens element disposed at the image-side end thereof. On the object side of this positive plastic lens element is disposed solely a lens element made of glass.