Abstract: A zoom lens system in which reductions in the number of lenses and entire lens length are realized is provided. The zoom lens system includes, in order from an object side to an image side, a first lens unit having negative optical power, a second lens unit having positive optical power, and a third lens unit having positive optical power. During zooming from a wide-angle end to a telephoto end, an interval between the first lens unit and the second lens unit reduces and an interval between the second lens unit and the third lens unit changes. An aspherical lens is used for a positive lens element of the first lens unit. Shapes of respective lens elements composing the first lens unit, an interval therebetween, and the like are suitably set.

Abstract: A zoom lens system that has a structure suitable to widen a field angle and realizes high optical performance over the entire zoom range is provided. The zoom lens system includes, in order from an object side to an image side, a first lens unit having negative optical power, a second lens unit having positive optical power, a third lens unit having negative optical power, and a fourth lens unit having positive optical power. During zooming from a wide-angle end to a telephoto end, an axial interval between the first lens unit and the second lens unit reduces, an axial interval between the second lens unit and the third lens unit increases, and an axial interval between the third lens unit and the fourth lens unit reduces. In the zoom lens system, a back focus and refractive indices of the respective lens units are suitably set.

Abstract: A zooming lens is suitable for projecting images produced by a display device onto a screen. The zooming lens includes a first set of lenses and a second set of lenses, wherein the second set of lenses is disposed in the optical path between the first set of lenses and the display device. The first set of lenses includes first lens, second lens, third lens, and fourth lens sequentially, and the fourth lens is adjacent to the second set of lenses. The second set of lenses includes fifth lens, sixth lens, seventh lens, and composite lens sequentially, and the composite lens is adjacent to a side of the display device. The optical focusing of the lenses, from the first one through the seventh and to the composite lens, are positive, negative, negative, positive, positive, negative, positive value and positive, respectively. The composite lens includes two optical lenses.

Abstract: Provided is a zoom lens system suitably used for, for example, an image taking optical system of a camera including a solid-state image pickup element. The zoom lens system includes a first lens unit having negative optical power, a second lens unit having positive optical power, and a third lens unit having positive optical power. During zooming, an interval between the first lens unit and the second lens unit and an interval between the second lens unit and the third lens unit are changed. The first lens unit consists of a first lens element having negative optical power and a second lens element having positive optical power. The first lens element has an aspherical surface. The first lens element is made of a material having a high refractive index.

Abstract: A macro lens comprised of a front lens group of a retrofocus type and a rear lens group of which component lenses are aligned in the order from the closest to the subject.

Abstract: The zoom lens system and camera using the same include, in order from an object side, a first lens group having negative refracting power and a second lens group having positive refracting power. Zooming is carried out at least by changing the distance between the first and second groups. The first lens group includes six lenses, a first lens which is negative meniscus lens having a concave surface toward an image side, a second lens which is negative meniscus lens having a concave surface toward the image side, a third lens which is negative lens having a concave surface toward the image side, a fourth lens which is positive lens having convex surfaces, a fifth lens having negative power and a sixth lens having positive power. The second lens group includes six lenses and the following condition is satisfied. 0.07<d12/f2G<0.30 where d12 is an air space on an optical axis between the first lens and the second lens in the second lens group, and f2G is a focal length of the second lens group.

Abstract: The invention provides a zoom lens that comprises a reduced number of lens elements, is compact and simplified, and has high image-formation capability, thereby achieving thorough size reductions in video cameras or digital cameras, and an electronic imaging system using the same. The zoom lens comprises a first lens group G1 of negative refracting power, a second lens group G2 of positive refracting power and a third lens group G3 of positive refracting power. Upon zooming from the wide-angle end to the telephoto end of the zoom lens, the second lens group G2 moves toward the object side alone of the zoom lens, and the third lens group G3 moves while the spacing between the third lens group G3 and the second lens group G2 varies. The second lens group G2 is composed of a front subgroup and a rear subgroup.

Abstract: A zoom lens system has, in order from an enlargement side, a first lens unit having negative optical power, a second lens unit having positive optical power, a third lens unit having positive optical power, a fourth lens unit having negative optical power, including an aperture stop, a fifth lens unit having positive or negative optical power, and a sixth lens unit having positive optical power. Zooming is achieved by varying the first to fifth variable distances between the lens units. The third and fifth lens units move from the enlargement side to the reduction side during zooming from the telephoto end to the wide-angle end. The zoom lens system is substantially telecentric toward the reduction side.

Abstract: The invention provides a zoom lens that operates in such a zooming mode and zoom arrangement that the number of lens elements is reduced to make the total thickness of each lens group thin while stable yet high image-formation capability is maintained, thereby achieving thorough size reductions in video cameras or digital cameras, and an electronic imaging system using the same. The zoom lens comprises a first lens group G1 of negative refracting power, a second lens group G2 of positive refracting power and a third lens group G3 of positive refracting power. For zooming from the wide-angle end to the telephoto end of the zoom lens upon focused on an infinite object point, the second lens group G2 moves toward the object side alone of the zoom lens, and the third lens group G3 moves in a locus different from that of the second lens group while the spacing between adjacent lens groups varies. The second lens group G2 is composed of two lens components, i.e.

Abstract: A zoom lens has a lens group of negative refractive power at the enlarging end and a lens group of positive refractive power at the reducing end, both of which are fixed during zooming. The lens group of negative refractive power includes two lens components of negative refractive power, and at least one of the lens groups includes a thin plastic lens element with a lens surface bonded to a lens surface of a glass lens element, with the other lens surface of the plastic lens element having an aspheric shape. The lens group of negative refractive power consists of lens elements of negative refractive power. One of the two lens components is at the enlarging end of the zoom lens and includes a meniscus lens element of negative refractive power. The other lens component is adjacent the one lens component and is a biconcave lens component.

Abstract: A wide-angle zoom lens system includes a negative first lens group, a positive 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 distance between the first lens group and the second lens group decreases, and the distance between the second lens group and the third lens group decreases.

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 zoom leas includes a first lens unit of a negative optical power and a second and third lens unit each of a positive optical power. The second lens unit consists of a first and second lens sub unit, each of a positive optical power arranged respectively on an object side and an image side. Zooming is effected by moving the lens units such that the distance between the first and second lens unit is smaller at a telephoto end than at a wide-angle end and that the distance between the second and third lens unit is larger. Focusing is effected by moving the second lens sub unit or the third lens unit where, when focusing on an object at infinity, the distance between the first lens sub unit and the second lens sub unit and the focal length of the entire system satisfy a predetermined condition.

Abstract: A projection lens of the following structure was invented for the purpose of providing a bright projection optical system with the F-number of approximately 2 or lower while maintaining good optical characteristics, in an image display apparatus. The projection lens is constructed of six lens units, a first lens unit L1 of a negative optical power, a second lens unit L2 of a positive optical power, a third lens unit L3 of a positive optical power, a fourth lens unit L4 of a negative optical power, a fifth lens unit L5, and a sixth lens unit L6 of a positive optical power, in the order named from the enlargement conjugate side, and four lens units (L2 to L5) out of the lens units move toward the enlargement conjugate side during zooming from the wideangle extreme to the telephoto extreme.

Abstract: The object is to provide a zoom lens system with an angle of view 2&ohgr; of about 74.1° to 11.8°, a zoom ratio of about 6.6, ultimately small in diameter and compact, being composed of less number of elements, and having high cost performance and superb optical performance. The system includes, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, at least one lens group, and a lens group Gm having positive refractive power as a whole. Zooming is carried out by changing an air space between the first lens group and the second lens group. The lens group Gm consists of, in order from the object, a positive lens component having a convex surface facing to an image side and a negative lens component having a concave surface facing to the object side. Particular conditions are satisfied.

Abstract: A projection zoom lens includes a first lens group having a negative refracting power, a second lens group having a positive refracting power, a third lens group having a negative refracting power, and a fourth lens group having a positive refracting power, which are arranged in that order from a screen side toward an image plane side along an optical axis. The first and the fourth lens group are kept stationary, and the second and the third lens group are moved along the optical axis to vary power from a limit wide angle power toward a limit telephoto power. The second lens group includes a 2nd-group 1st positive lens, a 2nd-group 1st compound lens formed by joining a 2nd-group 2nd positive lens having a convex surface on the image plane side and a 2nd-group 1st negative lens having a concave surface on the screen side, and a 2nd-group 3rd positive lens arranged in that order from the screen side toward the image plane side.

Abstract: The present invention provides a zoom lens system suitable for an image gathering system using a solid-state imaging device, having a zoom ratio of about three, a small total lens length, and superb optical performance. According to one aspect, in order from the object side, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having positive refractive power. Zooming is carried out by varying distances between adjacent lens groups. The first lens group includes two negative lens elements and a positive lens element. The second lens group includes three lens elements consisting of a first positive lens element, a second positive lens element, and a negative lens element. The third lens group includes at least one positive lens element. Predetermined conditional expressions are satisfied.

Abstract: A three-group zoom lens has, from an object side, a first group lens having a positive power, a second group lens having a negative power and a third group lens consisting of a positive lens. The second lens group includes an aperture stop. When a distance to be focused is infinity, only the first lens group and the second lens group move for zooming. At least one positive lens included in the zoom lens has an aspherical surface whose positive power is greater at a portion farther from an optical axis thereof. The zoom lens satisfies the following conditions: −0.85<f2/f1<−0.65 and 5.0<f3/fw<8.0  where, fw represents a focal length when positioned at a wide-extremity, and f1, f2 and f3 respectively represent focal lengths of the first, second and third lens groups.

Abstract: A zoom lens system including a first through third lens groups. The combined power of the first and second lens groups is positive. Upon zooming from the short focal length extremity towards the long focal length extremity, all the three lens groups are moved from the image towards the object. The zoom lens system satisfies the following conditions: 0.01<(d12W−d12T)/fW<0.1  (1); 3.5<fT/f12W<6.0  (2); 4.0<fT/|f3G|<8.

Abstract: A wide-angle zoom lens system including a negative first lens group, a positive second lens group, a diaphragm, and a positive third lens group, in this order from the object; whereby upon zooming from the short focal length extremity towards the long focal length extremity, each lens group is arranged to move so that the space between the first and second lens groups and the space between the second and third lens groups are narrowed; and the diaphragm moves integrally with the third lens group. At least one negative lens element having a concave surface facing towards the image is provided in the first lens group, and the concave surface of the at least one negative lens element is an aspherical surface; and the wide-angle zoom lens system preferably satisfies the following condition; 0.8<X1/fS<2.

Abstract: A zoom lens disclosed herein, having excellent optical performance within a full zoom range, is appropriate for use as a photographing lens for a lens-shutter camera, a video camera, and a digital still camera. The zoom lens includes at least four lens units from the object side, i.e., a first lens unit of negative refractive power, a second lens unit of positive refractive power, a third lens unit of positive refractive power, and a fourth lens unit of negative refractive power. A zooming operation is performed by axially moving the lens units so that the spacing between the first lens unit and the second lens unit becomes wider at the telephoto end than at the wide-angle end, that the spacing between the second lens unit and the third lens unit becomes wider at the telephoto end than at the wide-angle end, that the spacing between the third lens unit and the fourth lens unit becomes narrower at the telephoto end than at the wide-angle end.

Abstract: A wide-angle zoom lens system including a negative first lens group, a positive second lens group, a diaphragm, and a positive third lens group, in this order from the object; whereby upon zooming from the short focal length extremity towards the long focal length extremity, each lens group is arranged to move so that the space between the first and second lens groups and the space between the second and third lens groups are narrowed; and the wide-angle zoom lens system preferably satisfies the following condition: 0.36<(D2S−D2L)/(fL−fS)<0.

Abstract: In a zoom lens having a variable power ratio representing a ratio of a focal length at a telephoto end position to a focal length at a wide angle end position being not less than 2.5 times, the zoom lens includes, in the order named from an object side: a first lens group having a negative focal length; a second lens group having an aperture-stop and a positive focal length; and a third lens group having a positive focal length. When a magnification is varied from the wide angle end position to the telephoto end position, all of the first, second and third lens groups are moved in an optical axis direction of the zoom lens so that a distance between the first and second lens groups is decreased. The first lens group Includes, in the order named from the object side, a first positive lens whose convex surface faces the object side, a second negative meniscus lens whose convex surface faces the object side, a third negative lens, and a fourth positive lens.

Abstract: A zoom lens for primary use with a projection screen television system is disclosed having five lens groups, in sequential order from the enlarging side, of negative, positive, positive, negative, and positive refractive power. The first lens group and the fifth lens group are fixed, and the axial positions of the second lens group, the third lens group, and the fourth lens group vary when zooming so as to provide a change in magnification and to correct for shifting of the image surface which otherwise would occur with zooming. Specified conditions are satisfied in order to provide a zoom lens that is compact, is well-corrected for aberrations over the entire range of zoom, has a sufficient back focus on the reducing side for insertion of lens components needed for projecting color images, is nearly telecentric on its reducing side, and provides a sufficiently bright image with a wide-angle of view.

Abstract: An improved zoom lens constitutes a plurality of lens groups of different focal length. Through adjusting the position of the lens groups, different zooming ratio may be obtained. Higher image resolution and lower cost may also be achieved through using different lens material. The lens groups have respectively focal length combination of positive, negative, positive and positive. The second and fourth lens groups are movable for obtaining high quality image.

Abstract: A zoom lens system having a negative first lens group and a positive second lens group in this order from the object, each of which is arranged to move for zooming; the first negative lens group including a first single positive lens element, a second single negative meniscus lens element having convex surface facing the object, a third single negative lens element and a fourth a positive single lens element having a convex surface facing the object, in this order from the object; the second positive lens group including a fifth a positive biconvex single lens element, a sixth positive single meniscus lens element having the convex surface facing the object, a seventh negative biconcave single lens element and an eighth positive single lens element, in this order from the object; and the following condition is satisfied:(n.sub.2 +n.sub.3)/Z<1.32 (1)Wherein n.sub.i designates the refractive index of the i-th lens; Z designates the zoom ratio of the zoom lens system.

Abstract: The invention provides a compact zoom optical system which can be reduced in terms of the lens length upon collapsing, albeit having a zoom ratio as 3 or greater. The zoom optical system comprises a first lens group G1 having positive power, a second lens group G2 having positive power and a third lens group G3 having negative power. For zooming from the wide-angle end to telephoto end of the system, the lens groups move together toward the object side while the space between the first group G1 and the second group G2 becomes wide and the space between the second group G2 and the third group G3 becomes narrow. The second group G2 comprises a front lens subgroup G.sub.2A having negative power and a rear lens subgroup G.sub.2B, between which an aperture stop S is located. At least one aspheric surface is used in the rear subgroup G.sub.2B in the second group G2. The optical system satisfies 0.4<f.sub.W /f.sub.1G <1.0 where f.sub.W is the focal length of the optical system at the wide-angle end and f.sub.

Abstract: A zoom lens system for use in a camera having a color filter and a CCD achieves a magnification ratio of about 2.9 or greater and a back focus of about 9.2 or greater. The zoom lens system includes in order from an object side of the lens system, a first lens group having a negative refracting power, a second lens group spaced from the first lens group and having a positive refracting power and a third lens group spaced from the second lens group and having a positive refracting power. One or both of the fifth and an eighth lens surface has an aspherical surface, the fifth and eighth lens surfaces being counted from the object side. The second lens group includes five lenses with an extra lens being located at a far end of the second lens group relative to the object side. Each of the first, second and third lens groups is movable from a first position when the lens system is in a wide position to a second position when the lens system is in a tele position.

Abstract: A super wide-angle zoom lens includes at least a negative first lens group and a positive second lens group, in this order from an object side. A zooming operation is carried out by relatively moving the lens groups. When a photographing area is defined by a rectangular area, a boundary of a circular image forming area formed by the zoom lens is at least partially disposed in the rectangular photographing area at the shortest focal length of the zoom lens.

Abstract: A zoom lens system of compact size having a small number of lenses and a large field area is provided, comprising, in the following order from the object side, a first lens group G1 with a negative refractive power and a second lens group G2 with a positive refractive power, wherein zooming is executed by changing dead space between lens groups G1 and G2. The first lens group G1 comprises, in the following order from the object side, a first lens group front group G.sub.1F with a negative refractive power, and a first lens group rear group G.sub.1R with either a negative refractive power or a positive refractive power having at least one set of color erasable negative lens components L.sub.n and positive lens components L.sub.p. Focusing is executed by moving only front group G.sub.1F.

Abstract: A zoom lens system including, in order from the object side, a first lens unit having a negative refractive power and a second lens unit having a positive refractive power, in which zooming is effective by varying the spacing between the first lens unit and the second lens unit. The first lens unit has, in order from the object side, a negative meniscus lens element having a convex surface directed toward the object side, a negative lens element and a positive lens element. The second lens unit has, in order from the object side, a positive lens element having a convex surface directed toward the object side, a positive lens element, a cemented negative lens element composed of a positive lens element and a negative lens element, which are cemented together and a positive lens element. The first and second lens units and the elements thereof are positioned and arranged in prescribed relative positions.

Abstract: A zoom lens comprises a first lens unit having a positive refractive power, a second lens group having a negative refractive power, an iris and a third lens unit having a positive refractive power, arranged in this sequence as viewed from an object. The third lens unit comprises a lens unit 3a and a lens unit 3b arranged in this sequence as viewed from the object, with a large air gap therebetween. Zooming from a short focal length end to a long focal length end is effected by moving the second lens group from a unit side to a image side and moving the first lens unit and the third lens unit to depict convex loci toward the object. The zoom lens meets the condition of-0.3<HF.sub.3 /f.sub.3 <0.20.5<l.sub.3 /f.sub.3 <1.5whereHF.sub.3 is a distance between an apex of a lens of the third lens group facing the object and a front principal point of the third lens unit,f.sub.3 is a focal length of the third lens unit, andl.sub.3 is an air gap between the lens unit 3a and the lens unit 3b.

Abstract: A zoom lens includes, in succession from the greatly conjugate side to the little conjugate side, a first lens unit having negative refractive power, and a second lens unit having positive refractive power. Zooming from the wide angle side to the telephoto side is effected by at least the second lens unit being moved toward the greatly conjugate side. The zoom lens satisfies the following condition:bf.sub.w /f.sub.w >1.6,where f.sub.w is the focal length of the entire system at the wide angle end, and bf.sub.w is the distance from the last lens surface of the second lens unit to the little conjugate side.

Abstract: A zoom lens system for a limited conjugate distance comprises at least three lens units which can be divided into, from an object side to an image side, a front lens group having a positive refracting power and a rear lens group having a positive refracting power. An axial distance between the front lens group and the rear lens group varies by a focusing operation. A zooming operation is performed by one of the front lens group and the rear lens group including at least two lens units. The zoom lens system fulfills the condition of l=m wherein l represents an object focal length of the zoom lens system, and m represents an axial distance between an object point and an object principal point of the front lens group.