Abstract: Provided is a lens barrel having, in order from an object side to an image side, a first to a third group lens, the lens barrel including: a fixed frame; a cam frame supported by the fixed frame so as to be rotationally movable in a optical axis direction between a forward and a backward movement ends; and a shutter frame which moves in the optical axis direction in a rotation restricted state, through the rotation of the cam frame, in which: a third group frame is fixed to the shutter frame so that the object side of the third group lens is arranged on an inner peripheral side of the shutter frame; and the second frame is configured so that the image side of the frame is stored on the inner peripheral side of the shutter frame when the cam frame is positioned at the backward movement end.

Abstract: A zoom lens comprises, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit, and a fourth lens unit having a positive refractive power. The fourth lens unit includes a forty-first lens unit having a negative refractive power and arranged at the object side with reference to the longest air gap and a forty-second lens unit having a positive refractive power and arranged at the image side with reference to the air gap. The forty-first lens unit includes a negative 411st lens, and the forty-second lens unit includes a positive 421st lens. Abbe numbers and partial dispersion ratios of materials of the 411st lens and the 421st lens ?d411, ?gF411, ?d421 and ?gF421 are appropriately set.

Abstract: A zoom lens includes first to fourth lens units in order from the object side to the image side. The first, third, and fourth lens units have a positive refractive power. The second lens unit has a negative refractive power. Distances between the lens units are changed during zooming. The first lens unit is composed of a cemented lens including a first lens having a negative refractive power and a second lens having a positive refractive power arranged in order from the object side to the image side. The Nd1a and ?d1a are a refractive index and an Abbe number, respectively, of a material of the first lens for the d-line and are adequately set.

Abstract: A four-piece imaging lens module includes a fixed aperture diaphragm, a first lens, a second lens, a third lens and a fourth lens arranged from an object side to an image side in a sequence of: the diaphragm; the first lens of a positive refractive power, having a convex surface on the object side and at least one aspheric surface; the second lens of a negative refractive power with a meniscus shape, having a convex surface on the image side and at least one aspheric surface; the third lens of a positive refractive power with a meniscus shape, having a concave surface on the object side and at least one aspheric surface; the fourth lens of a positive refractive power, having a concave surface on the image side and at least one aspheric surface. The invention is to provide a four-piece imaging lens module with higher definition and higher yield rate.

Abstract: A zoom lens system, in order from an object side to an image side, comprising a first lens unit of positive power, a second lens unit of negative power, a third lens unit of positive power, and a fourth lens unit of positive power, wherein in zooming, the first to the fourth lens units are moved along the optical axis such that the air spaces between the individual lens units should vary, so that magnification change is achieved, and wherein the conditions: ?0.60<M2/fG2<?0.07, ?W?30, and fT/fW?4.5 (M2 is an amount of axial movement of the second lens unit in zooming, fG2 is a composite focal length of the second lens unit, ?W is a half view angle at a wide-angle limit, and fT and fW are focal lengths of the entire system at a telephoto limit and at a wide-angle limit, respectively) are satisfied, an imaging device and a camera are provided.

Abstract: Disclosed is an imaging lens having both high heat resistance that enables the imaging lens to be mounted on a printed circuit board by a reflow mounting method and a high optical performance. The imaging lens includes: a first positive lens group; a second negative lens group; a third positive lens group; and a fourth positive or negative lens group. Each of the first to fourth lens groups includes a parallel plane glass plate and a resin lens that has heat resistance and is arranged on the parallel plane glass plate so as to be integrated with the parallel plane glass plate.

Abstract: A zoom lens comprises the following lens groups in the order from an object side: a first lens group having a positive refracting power; a second lens group having a negative refracting power; a third lens group having a positive refracting power; and a fourth lens group having a positive refracting power; wherein, upon zooming, at least the first lens group and the fourth lens group move to the object side; and wherein the third lens group comprises a negative meniscus lens with a convex surface on an image side and with both side faces thereof being exposed to air, which is located nearest to the image side.

Abstract: Provided is a zoom lens having a high magnification and excellent optical performance over an entire zoom range between a wide-angle end and a telephoto end. The zoom lens includes, in order from object side to image side: a first lens unit having positive refractive power; a second lens unit having negative refractive power; a third lens unit having positive refractive power; and a fourth lens unit having positive refractive power, and performs zooming while the respective lens units move, in which: during zooming from wide-angle end to telephoto end, the first unit moves closer to object side at telephoto end than at wide-angle end and the fourth unit moves along a locus convex to object side; and a focal length of the second unit, a focal length of the zoom lens at wide-angle end, and an imaging magnification of the fourth unit at telephoto end are appropriately set.

Abstract: A scan lens for an imaging device includes first, second, third, and fourth lens elements optically positioned in ascending numeric order between a scanning component and an imaging surface. The first lens element has an optical power in an in-scan direction of the imaging device and an optical power in a cross-scan direction of the imaging device, the optical power in the cross-scan direction being positive and greater than the optical power in the in-scan direction. The second lens element has a negative optical power in the in-scan and cross-scan directions. The third lens element has a positive optical power in the in-scan direction and cross-scan directions. The fourth lens element has an optical power in the in-scan direction and a positive optical power in the cross-scan direction, the optical power in the cross-scan direction being greater than the optical power in the in-scan direction.

Abstract: An optical lens system for taking image comprises: a first lens element with positive refractive power, an Abbe Number of the first lens element being V1, and it satisfying the relation: 50<V1<60; a second lens element with negative refractive power having a concave object-side surface and a convex image-side surface; a third lens element having a convex object-side surface and a concave image-side surface, at least one of the object-side and the image-side surfaces of the third lens element being aspheric; a fourth lens element having at least one aspheric surface; and an aperture stop being located in front of the second lens element.

Abstract: A zoom lens includes 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. The first and third lens units are movable such that they are located closer to the object side at a telephoto end than at a wide-angle end. The fourth lens unit is movable with a locus convex towards the object side. A distance between the first and second lens units at the telephoto end, a distance between the second and third lens units at the telephoto end, a focal length of the first lens unit, a focal length of the second lens unit, and a focal length of the third lens unit, and a focal length of the entire zoom lens at the wide-angle end are appropriately set.

Abstract: A zoom lens system includes, in order from an 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 positive refractive power, and a fourth lens unit having a positive refractive power; and in a telephoto end as compared with a wide-angle end, a space between the first lens unit and the second lens unit increases, a space between the second lens unit and the third lens unit decreases, and a space between the third lens unit and the fourth lens unit changes.

Abstract: The inventive lens barrel comprises: a first group frame 12 retaining the first group lens 21 with a positive refractivity and being movable on the optical axis; a second group frame 11 retaining the second group lens 22 with a negative refractivity and being movable on the optical axis; a third group frame 10 retaining an aperture diaphragm 10b and the third group lens 23, and being movable on the optical axis and pivotable perpendicular to the optical axis in such a manner that the third group frame 10 can move the aperture diaphragm 10b and the third group lens 23 to the position on the optical axis O in a imaging standby state, in which the lens barrel 1 is extended, and move them to the position out of the optical axis O in the retracted state, in which the lens barrel 1 is shortened; and, a fourth group frame 13 retaining the fourth group frame 24 with a positive refractivity, and being movable on the optical axis, and being arranged such that it can retract the aperture diaphragm 10b and the third grou

Abstract: A zoom lens and imaging apparatus implementing four lens groups including a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a fourth lens group G4 having a positive refractive power. When a positional state is varied from a wide-angle-end state to a telephoto-end state, the second lens group is moved to an image side, and the fourth lens group is moved to compensate for image plane variation caused by the movement of the second lens group.

Abstract: An object is to provide a zoom lens system that can realize high image quality, a large aperture and a small size simultaneously and that can optically compensate blur of the image due to hand blur, vibration or the like, an imaging device and a camera. The present invention relates to a zoom lens system, in order from the object side to the image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power and a fourth lens unit having positive optical power, wherein variable magnification is achieved by moving at least three lens units in an optical axis direction, focusing is achieved by moving the fourth lens unit in the optical axis direction, blur of the image is compensated by moving the third lens unit in a direction perpendicular to the optical axis, and at least one of a condition (1): 0<(|?L|·fW)/(fT·IM)<10×10?2 and a condition (2): 0.005<(|?L3|·fW)/(fT·IM)<0.15 (here, Z=fT/fW>8.

Abstract: A zoom lens system includes, in order from an object side to an 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. The distances between the adjacent lens units are changed during zooming. By appropriately setting the lens configurations and focal lengths of the first lens unit and the second lens unit, a compact zoom lens system is realized.

Abstract: A small projection lens includes a first lens, which is a biconvex lens, an aperture, an aperture diaphragm (or an aperture), a second lens, which is a negative meniscus lens having a concave surface facing a magnification side, a third lens, which is a positive meniscus lens having a convex surface facing a reduction side, and a fourth lens, which is a biconvex lens having aspheric surfaces at both sides on an optical axis, arranged in this order from the magnification side. A minimum portion of the length of all lens elements of the small projection lens in a diametric direction vertical to the optical axis is equal to or less than 15 mm, and the small projection lens satisfies the following conditional expression: 2.5<?/S<10.0 (where S indicates the maximum length of a magnification-side image (inch) and ? indicates a magnifying power).

Abstract: A zoom lens includes, in order from an object to an image, 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 varying a field angle from a wide-angle end to a telephoto end, the first lens group and the third lens group being moved to be located on the object side at the telephoto end rather than at the wide-angle end such that a distance between the first lens group and the second lens group increases, a distance between the second lens group and the third lens group decreases, and a distance between the third lens group and the fourth lens group increases.

Abstract: A zoom lens comprises the following lens groups in the order from an object side: a first lens group having a positive refracting power; a second lens group having a negative refracting power; a third lens group having a positive refracting power; and a fourth lens group having a positive refracting power; wherein, upon zooming, at least the first lens group and the fourth lens group move to the object side; and wherein, upon focusing, the fourth lens group comprises a front lens group, and a rear lens group arranged with an air space on an image side of the front lens group, and the rear lens group is moved in a direction of an optical axis of the zoom lens.

Abstract: Disclosed is an imaging lens having both high heat resistance that enables the imaging lens to be mounted on a printed circuit board by a reflow mounting method and a high optical performance. The imaging lens includes: a first positive lens group; a second negative lens group; a third positive lens group; and a fourth positive or negative lens group. Each of the first to fourth lens groups includes a parallel plane glass plate and a resin lens that has heat resistance and is arranged on the parallel plane glass plate so as to be integrated with the parallel plane glass plate.

Abstract: A projecting lens system includes a first lens positive in power, a second lens negative in power, a third lens positive in power, and a fourth lens positive in power. The projecting lens system meets a criteria of 1.4<TT/f<1.7; where TT denotes a total length of the projecting lens system and f denotes an effective focal length of the projecting lens system.

Abstract: An image pickup apparatus having a wide angle zoom lens system includes a zoom lens system, and an image pickup element which is disposed at an image side of the zoom lens system. The zoom lens system includes in order from an object side thereof, a first lens unit G1 having a positive refracting power, a second lens unit G2 having a negative refracting power, a third lens unit G3 having a positive refracting power, a fourth lens unit G4 having a positive refracting power, and an aperture stop S which is disposed between the second lens unit G2 and the third lens unit G3. A zooming is carried out from a wide angle end to a telephoto end by fixing a position of the first lens unit, and changing a distance between the lens units by moving at least the second lens unit G2 and the third lens unit G3, and the following conditional expressions are satisfied. 33°<tan?1(IHw/fw)??(1) 3<f1g/fw<5??(2).

Abstract: A zoom lens includes, in order from an object side to an image 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 positive refractive power, and a rear lens unit including one or more lens units and having an overall positive refractive power. In the zoom lens, the third lens unit includes a first subunit having a positive refractive power and including one lens component having a positive refractive power, an aperture stop, and a second subunit including a negative lens. In the third lens unit of the zoom lens, a focal length of each of the first subunit and the second subunit is appropriately set.

Abstract: The invention relates to a less costly zoom lens that can offer a sensible tradeoff between size reductions and high zoom ratios with a well-kept image quality, and that lends itself to an electronic imaging device such as a CCD or CMOS. The zoom lens comprises a positive first lens group G1, a negative second lens group G2, a positive third lens group G3 and a positive fourth lens group G4, wherein zooming is implemented by changing the space between adjacent lens groups. The first lens group G1 comprises one positive lens, the second lens group G2 comprises two lenses, and the fourth lens group G4 comprises one positive lens. The zoom lens satisfies condition (1) needed for making sure an ideal situation for the zoom ratio and low costs and condition (2) needed for the first lens group to comprise a minimum one lens and to hold back chromatic aberration of magnification as much as possible.

Abstract: The inventive lens barrel comprises: a first group frame 12 retaining the first group lens 21 with a positive refractivity and being movable on the optical axis; a second group frame 11 retaining the second group lens 22 with a negative refractivity and being movable on the optical axis; a third group frame 10 retaining an aperture diaphragm 10b and the third group lens 23, and being movable on the optical axis and pivotable perpendicular to the optical axis in such a manner that the third group frame 10 can move the aperture diaphragm 10b and the third group lens 23 to the position on the optical axis O in a imaging standby state, in which the lens barrel 1 is extended, and move them to the position out of the optical axis O in the retracted state, in which the lens barrel 1 is shortened; and, a fourth group frame 13 retaining the fourth group frame 24 with a positive refractivity, and being movable on the optical axis, and being arranged such that it can retract the aperture diaphragm 10b and the third grou

Abstract: A compact lens system that includes a first lens that is a meniscus lens with positive refractive power and having aspheric surfaces on both sides, and a convex surface on a surface facing an object; a second lens formed of a biconcave lens having aspheric surfaces on both sides; a third lens having aspheric surfaces on both sides and having positive refractive power; and a fourth lens formed of a biconcave lens having aspheric surfaces on both sides and an inflection point on an upper aspheric surface. The first through fourth lenses are arranged sequentially from the object, and an aperture diaphragm is disposed on the object side of the first lens.

Abstract: The imaging lens is configured to include, in an order arranged from an object side: a first lens having a substantially convex surface formed at the object side and having a positive refractive power; a second lens constituted of a meniscus lens having a substantially concave surface formed at the object side and having a negative refractive power; a third lens having substantially convex surfaces formed at both sides, respectively; and a fourth lens constituted of a meniscus lens having a substantially convex surface at the object side and having a positive refractive power. Further, a space of at least 1.0 mm is ensured between the first lens and the second lens. This allows a diaphragm mechanism of a certain thickness having a diaphragm to be arranged between the first lens and the second lens.

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, at least the first lens group, the second lens group and the third lens group move along the optical axis direction so 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, and the distance between the third lens group and the fourth lens group increases. The wide-angle zoom lens system satisfies the following conditions: ?0.7<fw/f2<?0.5??(1) 0.4<X1/ft<0.

Abstract: Providing a zoom lens system with a vibration reduction function, a high zoom ratio, and a wide angle of view, an imaging apparatus, a method for vibration reduction, and a method for varying a focal length. The system includes, in order from an object, a first lens group having positive power, a second lens group having negative power, a third lens group having positive power, and a fourth lens group having positive power. Upon zooming from a wide-angle end to a telephoto end, a distance between the first and the second lens groups increases, a distance between the second and the third lens groups decreases, and a distance between the third and the fourth lens groups varies. The third lens group consists of a front group and a rear group. Vibration reduction is carried out by moving only the rear group perpendicularly to the optical axis. Given conditions are satisfied.

Abstract: A high-zoom-ratio zoom lens having superb optical performance despite compactness and a high zoom ratio. The lens includes, in order from an object, a first group having positive power; a second group having negative power; a third group having positive power; and a fourth group having positive power. The third group includes, in order from the object, a first positive lens having a convex surface facing the object, a second positive lens having a convex surface facing the object, a double concave negative lens having a radius of curvature of the image side surface smaller than that of the object side surface, and a third positive lens having a double convex shape. Any of lens surfaces composing the third group is an aspherical surface. Upon zooming from a wide-angle end to a telephoto end, all groups moving along the optical axis. Given condition is satisfied.

Abstract: A telephoto zoom lens system includes a positive first lens group, a negative second lens group as a focusing lens group, a diaphragm, 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, all the lens groups move toward the image. The second lens group includes a first 2a sub-lens group, and a second 2b sub-lens group, in this order from the object. The telephoto zoom lens system satisfies the following conditions: 1.6<fs/|f2|<2.1??(1) 0.45<|f2bn|/f2bp<0.8??(2) wherein fs: the focal length of the zoom lens system at the short focal length extremity; f2: the focal length of the negative second lens group (f2<0); f2bn: the focal length of the biconcave negative lens element of the second 2b sub-lens group (f2bn<0); and f2bp: the focal length of the biconvex positive lens element of the second 2b sub-lens group (f2bn>0).

Abstract: There is provided a subminiature imaging optical system including, sequentially from an object side to an image side: a first lens having positive refractive power; a second lens having negative refractive power and both sides concaved toward an image side; a third lens having positive refractive power and a meniscus shape with a convex image-side surface; and a fourth lens having positive refractive power. The first and second lenses have refractive power satisfying following condition 1, the second lens has a shape satisfying following condition 2, and the third and fourth lenses have refractive power satisfying following condition 3, 0.3<|f1/f2|<2.0??condition 1, 0.2<|R5/f2|<<4??condition 2, 0<|f3/f4|<10??condition 3, where f1 is a focal length of the first lens, f2 is a focal length of the second lens, f3 is a focal length of the third lens and f4 is a focal length of the fourth lens, and R5 is a radius of curvature of an image-side surface of the second lens.

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: A zoom lens system comprises, in order from an 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 positive refractive power and a fourth lens unit having a positive refractive power, during zooming from a wide-angle end to a telephoto end, at least the first lens unit and the third lens unit are moved toward the object side so as to increase a space between the first lens unit and the second lens unit and decrease a space between the second lens unit and the third lens unit, and predetermined conditions are satisfied.

Abstract: An imaging lens is provided and includes: a first lens of a positive lens; a second lens of a negative lens whose concave surface faces to an image side of the second lens; a third lens of a positive lens, whose both surfaces are aspheric, having a concave surface facing to an object side of the third lens; and a fourth lens of a meniscus lens, whose both surfaces are aspheric, having a convex surface facing to the object side near the optical axis, the lenses being arranged in this order from an object side, the first imaging lens satisfying the conditional expressions specified in the specification.

Abstract: A four-unit zoom lens system includes in order from an 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 positive refracting power, in which at a time of zooming from a wide angle end to a telephoto end, at least the first lens unit, the second lens unit, and the third lens unit move, and a space between the lens units changes, and a total number of lenses in the second lens unit is not more than three, and the zoom lens system satisfies the following conditional expressions. 1.2<(?2t/?2w)/(?3t/?3w)<6.0 and ??(1A) 3.0<ft/fw<20.

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

Abstract: A zoom lens comprises, in the following order from the object side to the image side, a positive first lens unit, a negative second lens unit, which moves during zooming, a positive third lens unit, and a positive fourth lens unit, which moves during zooming. The first lens unit includes a negative lens subunit and a positive lens subunit. The negative lens subunit includes at least two negative lenses each having a concave surface facing the image side and at least one positive lens arranged from the object side. The positive lens subunit includes at least one biconvex positive lens, a negative lens and at least two positive lenses arranged from the object side, or at least one biconvex positive lens, a cemented lens composed of a negative lens and a positive lens and at least one positive lens arranged from the object side.

Abstract: A projection objective for microlithography serves for imaging a pattern of a mask arranged in its object surface into an image field arranged in its image surface with a demagnifying imaging scale. It has a multiplicity of optical elements arranged along the optical axis of the projection objective, the optical elements being designed and arranged in such a way that the projection objective has an imageside numerical aperture NA>0.85 and a demagnifying imaging scale where |b|<0.05, and the planar image field having a minimum image field diameter suitable for microlithography of more than 1 mm.

Abstract: An infrared laser light source spreader has a first biconvex lens, a biconcave lens, a convex-concave lens, and a second biconvex lens. Light from an infrared laser light source is emitted incident to the first biconvex lens, spreads and exits to be incident on the biconcave lens, is further spread and inverted by the biconcave lens, exits to be incident on the convex-concave lens, which collimates the light, and becomes incident on the second biconvex lens, which spreads the light further.

Abstract: An imaging lens is provided and includes: in order from an object side of the imaging lens, a first lens having a convex surface on the object side and having a positive power; a second lens having a concave surface on the object side and having a negative power; a third lens having a positive power; and a fourth lens having a convex surface on the object side near a paraxial axis and having a meniscus shape. The imaging lens satisfies conditional expressions specified in the specification.

Abstract: An optical system includes a first optical element and a second optical element on at least one of an enlargement side and a reduction side relative to a point P at which a light axis and a paraxial chief ray intersect. Each of the first optical element and second optical element is composed of a solid material having a refractive light incident surface and a refractive light emergent surface. The optical system satisfies the following conditional expressions: ??gF1>0.0272, ??gF2<?0.0278, and f1×f2<0 where ??gF1 and ??gF2 denote anomalous partial dispersion values of the first and second optical elements for the g-line and F-line, respectively, and f1 and f2 denote focal lengths of the first and second optical elements, respectively, when the light incident surfaces and the light emergent surfaces of the first and second optical elements are in contact with air.

Abstract: An imaging lens is provided and includes: in order from the object side, a first lens having a convex surface on the object side and having a positive power; an aperture diaphragm; a second lens having a concave surface on the object side and having a negative power; a third lens having a positive power; and a fourth lens having a convex surface on the object side near the optical axis, the fourth lens having a meniscus shape. The imaging lens satisfies conditional expressions: 0.2<D2/f<0.4 ??(1) TL/f<1.3 ??(2) where f represents a focal distance of the imaging lens; D2 represents an air interval between the first lens and second lens along an optical axis of the imaging lens; and TL represents a distance (along the optical axis) from an object-side surface of the first lens to an image forming surface.

Abstract: A compact zoom lens optical system suitable for use in a camera using a solid state photographing device and providing excellent correction of color aberrations, high zooming ratio, and telecentricity. The zoom lens optical system includes: a first lens group having a positive refractive power, the first lens group including two lenses; a second lens group having a negative refractive power; a third lens group having a positive refractive power; a fourth lens group having a positive refractive power; and a fifth lens group having a positive refractive power. The first through fifth lens groups are sequentially arranged from an object side and the first lens group is moved during zooming from a wide angle position to a telephoto position.

Abstract: An image taking apparatus is equipped with a zoom lens system which comprises: 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, at least the first lens unit, the second lens unit, and the third lens unit move during zooming from a wide-angle end to a telephoto end so that a space between the first lens unit and the second lens unit increases, a space between the second lens unit and the third lens unit decreases, and a space between the third lens unit and the fourth lens unit increases, and the first lens unit is arranged closer to an image side in the wide-angle end than that in the telephoto end.

Abstract: A zoom lens for imaging an image onto a photosensitive element includes a first lens group, a second lens group, a third lens group and a fourth lens group. The second lens group is located and suitable for moving between the first lens group and the third lens group; the fourth lens group is located and suitable for moving between the third lens group and the photosensitive element. The first lens group, the second lens group, the third lens group, and the fourth lens group have a positive refractive power, a negative refractive power, a positive refractive power and a positive refractive power, respectively. Besides, the third lens group includes at least a hybrid lens and the second lens group includes at least an aspheric lens, the number of the aspheric lens is smaller than or equal to 2. Thus, manufacturing cost of the zoom lens mentioned above is lower.

Abstract: Disclosed is a zoom lens system, in order from an object side to an image side, including: a first lens unit having a positive optical power; a second lens unit having a negative optical power; a third lens unit having a positive optical power; and a fourth lens unit having a positive optical power, in which during zooming, intervals of the lens units are changed. In such a zoom lens system, a material having a large refractive index is adopted for a material constituting a negative lens element disposed on the most object side in the second lens unit, whereby high optical performance is realized while the whole lens system is miniaturized.

Abstract: A fast 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 fast zoom lens system satisfies the following conditions; 6.0<f1/fw<10.0??(1) 3.0<f3/fw<8.0??(2) wherein f1 designates the focal length of the positive first lens group; f3 designates the focal length of the positive third lens group; and fw designates the focal length of the entire fast zoom lens system at the short focal length extremity.

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: An imaging lens is provided and includes: in order from an object side of the imaging lens, a first lens having a convex surface on the object side and having a positive power; a second lens having a concave surface on the object side and having a negative power; a third lens having a positive power; and a fourth lens having a convex surface on the object side near a paraxial axis and having a meniscus shape. The imaging lens satisfies conditional expressions specified in the specification.