Abstract: A variable power optical system (1) comprises a first lens group (11) having a negative optical power, a second lens group (12) having a positive optical power, and a third lens group (13). The first to third lens groups are arranged in order from the object side to the image side. The first lens group (11) is composed of one negative lens (111) and is fixed in variable power. The third lens group (13) includes at least one aspherical surface. When the third lens group is divided into a front group and a rear group with the largest air space in the third group, the front group has a negative optical power, and the rear group has a positive optical power.

Abstract: A zoom lens includes, in the order from the object-side to the image-side thereof, a first lens group of a negative refractive power, a second lens group of a positive refractive power, and a third lens group of a positive refractive power. The first lens group includes, in the order from the object-side to the image-side thereof, a first lens of negative refractive power, and a second lens of positive refractive power. The second lens group includes, in the order from the object-side to the image-side thereof, a third lens of positive refractive power, a fourth lens of negative refractive power, and a fifth lens of negative refractive power.

Abstract: In an image forming optical system which includes in order from an object side, 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, and which includes maximum of five lens groups, and at the time of zooming from a wide angle end to a telephoto end, when a focal length of the overall image forming optical system is in a range of 1.2 fw to 1.8 fw, the first lens group G1 moves to be positioned more toward the object side than a position at the wide angle end, in a rectangular coordinate system in which, a horizontal axis is let to be ?d(LA) and a vertical axis is let to be nd(LA), when a straight line expressed by nd(LA)=a×?d(LA)+b(LA)(provided that a=?0.0267) is set, the image forming optical system satisfies a predetermined conditional expression.

Abstract: A zoom lens system includes a negative first lens group, positive second and third lens groups, wherein upon zooming from the short to the long focal length extremities, the distance between the first and second lens groups decreases and the distance between the second and third lens groups changes. The second lens group includes a biconvex positive lens element with an aspherical surface on each side, and a negative meniscus lens element with an aspherical surface, and a concave surface on the image side. The following condition (1) is satisfied: 5<m2t/m2w<8??(1), wherein m2t and m2w designate the lateral magnifications of the second lens group at the long and short focal length extremities, respectively, when focused on an object at infinity.

Abstract: An optical system includes at least one lens unit having a negative refractive power disposed closer to an object side than an aperture portion. The lens unit having a negative refractive power includes at least one positive lens and one negative lens. The ratio between the numbers of positive lenses and negative lenses included in the lens unit having a negative refractive power is appropriately set. The lens unit having a negative refractive power includes a plurality of negative lenses each having an appropriate Abbe number and relative partial dispersion and a positive lens having an appropriate Abbe number. A negative lens having the highest dispersion among the negative lenses is located in an appropriate position.

Abstract: A zoom lens includes, in order from an object, a first lens group G1 having negative refractive power; a second lens group G2 having positive refractive power; and a third lens group G3 having positive refractive power. The first lens group G1 comprises only one negative spherical lens (lens L11) and one plastic positive lens (lens L12) separated by an air gap. The second lens group G2 comprises three or fewer lenses, including a positive lens component (cemented lens comprising a lens L21 and a lens L22), and one plastic negative lens (lens L23). The following conditional expressions are satisfied: 0.50<f1PL/(?f2PL)<2.50 and 0.80<(?f1)/f2<1.35, where f1PL is a focal length of the plastic positive lens forming the first lens group G1, f2PL is the focal length of the plastic negative lens forming the second lens group G2, f1 is the focal length of the first lens group G1, and f2 is the focal length of the second lens group G2.

Abstract: A zoom lens system includes a first lens group of negative refractive power, a second lens group of positive refractive power and a third lens group of positive refractive power. The zoom lens system satisfies the following condition formulas: 0.78<|f2/f1|<0.91, and 0.72<L2/fT<0.87, where f1 represents an effective focal length of the first lens group, f2 represents an effective focal length of the second lens group, L2 is a displacement of the second lens group when the zoom lens system varies from a wide-angle state to a telephoto state, and fT represents an effective focal length of the zoom lens system which is in the telephoto state.

Abstract: To provide an image forming optical system that can achieve good correction of chromatic aberration, which is seriously needed particularly when the zoom ratio is high, while achieving slimness and a high zoom ratio and to provide an electronic image pickup apparatus equipped with such an image forming optical system, an image forming optical system has a lens group A including a lens component made up of a positive lens LA and a negative lens LB cemented together and having a negative refracting power as a whole. The lens group A is arranged between a lens group I closest to the object side and an aperture stop. The distance between the lens group I and the lens group A changes for zooming. The lens component has an aspheric cemented surface, and a certain condition concerning the shape of the aspheric surface is satisfied.

Abstract: A zoom lens includes, in order from the object side to the image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a rear group including one or more lens units. An aperture stop is included on the image side of the second lens unit, and the second lens unit and at least one of the lens units included in the rear group move during zooming. The Abbe number ?dj1 and the partial dispersion ratio ?gFj1 of a material of a refractive optical element j1 having a negative refractive power included in the second lens unit, the focal length fj1 of the refractive optical element j1, the focal length f2 of the second lens unit, and the anomalous partial dispersion ratio ??gFj1 of the refractive optical element j1 are set appropriately.

Abstract: A zoom lens primarily includes, in order from an object side to an image-forming side, a first lens group having negative refractive power; a second lens group having positive refractive power and at least consisting of a first lens and a second lens; and a third lens group having positive refractive power. The refractive index of the first lens (Nd21), the refractive index of the second lens (Nd22), the total length of the first lens group, the second lens group, and the third lens group (TTL), and the shortest focal length of the zoom lens (fw) satisfy the following conditions: Nd21?Nd22>0.1 and TTL/fw?1.3.

Abstract: A zoom lens system has a plurality of lens units each composed of at least one lens element and, in order from the object side to the image side, comprises: a negative first lens unit being composed of two lens elements; a positive second lens unit; and a positive third lens unit, wherein in zooming from a wide-angle limit to a telephoto limit during image taking, the individual lens units are moved along an optical axis such that an interval between the first lens unit and the second lens unit decreases and that an interval between the second lens unit and the third lens unit increases, so that magnification change is achieved, and wherein on the image side relative to the second lens unit, an aperture diaphragm is arranged that moves along the optical axis integrally with the second lens unit during zooming.

Abstract: A zoom lens system has a plurality of lens units each composed of at least one lens element and, in order from the object side to the image side, comprises: a negative first lens unit being composed of two lens elements; a positive second lens unit; and a positive third lens unit, wherein in zooming from a wide-angle limit to a telephoto limit during image taking, the individual lens units are moved along an optical axis such that an interval between the first lens unit and the second lens unit decreases and that an interval between the second lens unit and the third lens unit increases, so that magnification change is achieved, and wherein on the image side relative to the second lens unit, an aperture diaphragm is arranged that moves along the optical axis integrally with the second lens unit during zooming.

Abstract: A lens barrel is provided that includes a zoom optical system, a zooming unit, and a light adjusting mechanism. The zoom optical system includes a first, a second, and a third lens group. The second lens group is movable in a direction perpendicular to the optical axis and configured to move the optical image in the same direction. The zooming unit causes the zoom optical system to perform a zooming operation. The lens barrel is configured to change between an imaging state and a retracted state. In the imaging state, the zooming operation is performed and all the lens groups are aligned with one another. During the zooming operation, the first and third lens groups move independently of each other, and the light adjusting mechanism moves integrally with the second lens group. In the retracted state, the third lens group is disposed off center from the optical axis.

Abstract: A zoom lens includes, in the order from the object-side to the image-side thereof, a first lens group of a negative refractive power, a second lens group of a positive refractive power, and a third lens group of a positive refractive power. The first lens group includes, in the order from the object-side to the image-side thereof, a first lens of negative refractive power, and a second lens of positive refractive power. The second lens group includes, in the order from the object-side to the image-side thereof, a third lens of positive refractive power, a fourth lens of negative refractive power, and a fifth lens of negative refractive power.

Abstract: The present disclosure provides a zoom lens, wherein a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having the positive refractive power are disposed from an object side to an image side in order; and when a zooming state is changed from a wide angle end state to a telescopic end state, at least the first lens group and the second lens group are movable.

Abstract: The lens barrel is a lens barrel for forming an optical image of a subject on an imaging element, comprising a first lens unit, a second lens unit, a focus lens unit, a zoom mechanism, and a focus actuator. The focus lens unit is movably supported by the second lens unit in the optical axis direction. The operating force inputted to the zoom control is mechanically transmitted to at least one of the first lens unit and the second lens unit. The focus actuator is fixed to the second lens unit and electrically drives the focus lens unit relative to the second lens unit in the optical axis direction. The second lens unit or the focus lens unit is disposed nearest to the image plane in the optical system including the first lens element, the second lens element, and the focus lens.

Abstract: An imaging lens SL mounted in a single lens reflex digital camera 1 is composed of, in order from an object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. Upon focusing on a near-distance object from an infinitely distant object, a configuration is that at least any one of the first lens group G1 and the second lens group G2 is moved to the object side to vary a distance between the first lens group G1 and the second lens group G2. Accordingly, a downsized imaging lens having a small moving amount upon shooting a close range object, in which various aberrations are well corrected is provided.

Abstract: A zoom lens system of the present invention has a plurality of lens units each composed of at least one lens element and, in order from the object side to the image side, comprises: a first lens unit having negative optical power and composed of two lens elements; a second lens unit having positive optical power; and a third lens unit having positive optical power, wherein in zooming, at least the first lens unit and the second lens unit move along an optical axis, on the image side relative to the second lens unit, an aperture diaphragm is arranged that moves along the optical axis integrally with the second lens unit during zooming, the second lens unit is, in order from the object side to the image side, composed of a first cemented lens element by cementing two lens elements and a second cemented lens element by cementing two lens elements, and the condition is satisfied: 2.00<fG2a/fG2b<3.00 where, fG2a, fG2b: focal lengths of the first and second cemented lens elements.

Abstract: A zoom lens and a photographing apparatus including the zoom lens that includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power that are sequentially arranged from an object side; during zooming from wide to telephoto, the distance between the first and second lens groups decreases and the distance between the second and third lens groups increases; the first lens group includes a first lens having a negative refractive power and is a double-concave lens and a second lens having a positive refractive power that are sequentially arranged from the object side; and the second lens group includes a third lens having a positive refractive power, being disposed closest to the image side, and is a meniscus lens having a concave surface toward the object side.

Abstract: A zoom lens has a plurality of lens units including, in order from its object side to image side, a first lens unit having a negative refracting power composed of two lens elements including a biconcave negative lens and a positive lens, and a second lens unit having a positive refracting power composed of four lens elements including a positive lens and a negative lens. During zooming from the wide angle end to the telephoto end, a distance between the lens units changes, and the second lens unit moves toward the object side. The zoom lens has an aperture stop that moves integrally with the second lens during the zooming and satisfies a specific condition.

Abstract: A zoom lens comprising, in order from an object side: a first lens group G1 having positive refractive power; a second lens group G2 having negative refractive power; and a third lens group G3 having positive refractive power; each distance between said lens groups adjacent to each other changing upon zooming from a wide-angle end state to a telephoto end state, said first lens group G1 having a cemented lens including a negative lens L11, and said third lens group G3 having a cemented lens L32 and L33, and a given conditional expression being satisfied, thereby providing a downsized zoom lens having high optical performance.

Abstract: A zoom lens includes a first lens group of negative refractive power, a second lens group of positive refractive power and a third lens group of positive refractive power. The zoom lens satisfies the following condition formulas: 0.68<|f2/f1|<0.85, and 0.65<L2/fT<0.86, where f1 represents an effective focal length of the first lens group, f2 represents an effective focal length of the second lens group, L2 is a displacement of the second lens group when the zoom lens varies from a wide-angle state to a telephoto state, and fT represents an effective focal length of the zoom lens which is in the telephoto state.

Abstract: A zoom lens system comprising: a front unit having negative optical power as a whole and including a first lens unit located closest to the object side; and a rear unit having positive optical power as a whole, wherein at least the front unit moves along an optical axis in zooming, the first lens unit is composed of at most three lens elements, the rear unit includes a lens unit having an aperture diaphragm between lens elements, an air space between which is not varied in zooming, a sub lens unit comprising a part of a lens unit constituting the rear unit moves in a direction perpendicular to the optical axis, and the condition: 0.1<BF/fW<2.0 (?W>72°, FNOW<2.9, BF is a back focal length of the entire system at a wide-angle limit, fW is a focal length of the entire system at a wide-angle limit, ?W is a view angle at a wide-angle limit, FNOW is an F-number at a wide-angle limit) is satisfied; an imaging device; and a camera are provided.

Abstract: A zoom lens system has a plurality of lens units each composed of at least one lens element and, in order from the object side to the image side, comprises: a negative first lens unit being composed of two lens elements; a positive second lens unit; and a positive third lens unit, wherein in zooming from a wide-angle limit to a telephoto limit during image taking, the individual lens units are moved along an optical axis such that an interval between the first lens unit and the second lens unit decreases and that an interval between the second lens unit and the third lens unit increases, so that magnification change is achieved, and wherein on the image side relative to the second lens unit, an aperture diaphragm is arranged that moves along the optical axis integrally with the second lens unit during zooming.

Abstract: A zoom lens system has a plurality of lens units each composed of at least one lens element and, in order from the object side to the image side, comprises: a negative first lens unit being composed of two lens elements; a positive second lens unit; and a positive third lens unit, wherein in zooming from a wide-angle limit to a telephoto limit during image taking, the individual lens units are moved along an optical axis such that an interval between the first lens unit and the second lens unit decreases and that an interval between the second lens unit and the third lens unit increases, so that magnification change is achieved, and wherein on the image side relative to the second lens unit, an aperture diaphragm is arranged that moves along the optical axis integrally with the second lens unit during zooming.

Abstract: A zooming camera module includes a first lens group, a second lens group, and a third lens group. The first lens group is implemented on an optical axis at a fixed position, and has a negative total optical power. The second lens group is implemented on the optical axis and can be moved back and forth along the optical axis, to achieve zooming and focusing. The second lens group has a positive total optical power, and includes a liquid lens unit and at least one lens with non-zero optical power, wherein the at least one lens and the liquid lens are separately or integrally configured. The third lens group is implemented on the optical axis at a fixed position, and has a non-zero total optical power.

Abstract: A zoom lens is provided. The zoom lens includes a first lens group, a second lens group and a third lens group. The first lens group includes at least one lens. The second lens group includes at least one lens. The first lens group, the second lens group and the third lens group are arranged in order from an object side to an image side. The zoom lens satisfies following conditions: NdA<1.65, NdB<1.65, and GD2/GD1<1.35. NdA is a refraction index of the first lens group. NdB is a refraction index of the second lens group. GD1 is a thickness of the first lens group along an optical axis. GD2 is a thickness of the second lens group along an optical axis.

Abstract: A zoom lens includes a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, and a third lens unit having a positive refractive power. The first lens unit, the second lens unit, and the third lens unit are arranged in order from an object side to an image side. Distances between the lens units change during zooming. The first lens unit consists of two lenses. Radii of curvature of a lens surface closest to the object side and a lens surface closest to the image side in the first lens unit, a focal length of the first lens unit, and a focal length of the entire zoom lens at a telephoto end are set appropriately.

Abstract: An image pickup apparatus operable to reduce defocusing due to temperature changes is disclosed. An optical system comprises a glass lens and a plastic lens, wherein a power of the plastic lenses is smaller than that of the glass lens. An image pickup device picks up an object image that has passed through the optical system as a defocused object image including an area with a large-depth-of-field light and a blurred area. An image processing device generates an image signal with a smaller blur than the blurred object image from the image pickup device.

Abstract: An embodiment of this invention provides a zoom lens, which primarily comprises, in order from an object side to an image-forming 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. The second lens group includes a plurality lenses in which the refractive index of the lens nearest to the object side is NDo, the refractive index of the lens nearest to the image-forming side is NDi, and NDo and NDi satisfy: NDi-NDo>0.1.

Abstract: A high-performance zoom lens system which is compact and has a wide view angle at a wide-angle limit and a high zooming ratio in a balanced manner, in order from an object side to an 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 the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and the conditions: ?2.0<f2/fW<?1.1, fT/fW>6.

Abstract: A zoom lens system of the present invention has a plurality of lens units each composed of at least one lens element and, in order from the object side to the image side, comprises: a first lens unit having negative optical power and composed of two lens elements; a second lens unit having positive optical power; and a third lens unit having positive optical power, wherein in zooming, the lens units are moved such that an interval between the first lens unit and the second lens unit should decrease and that an interval between the second lens unit and the third lens unit should increase, so that magnification change is achieved, wherein the first lens unit is, in order from the object side to the image side, composed of a first lens element having negative optical power and a second lens element having positive optical power, and wherein the condition is satisfied: 0.50<fL2/fT<1.00 where, Z=fT/fW>4.

Abstract: A zoom lens including, in a sequence from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a succeeding lens group having an overall positive refractive power, and having a high zoom magnification and a compact size.

Abstract: A zoom lens includes in order from an object side to an image side and arranged along an optical axis thereof, a first lens unit having a negative refractive power, and a second lens unit having a positive refractive power. A distance between each lens unit changes when zooming from a wide-angle end to a telephoto end. The first lens unit includes a first lens sub-unit including a positive lens element and a negative lens element, and having a negative refractive power, and a second lens sub-unit including a single negative lens element. Focusing is performed by moving the second lens sub-unit in an optical axis direction, a focal length of the second lens sub-unit f1b and a focal length of the entire zoom lens fw at a wide-angle end are suitably set based on predetermined mathematical expressions.

Abstract: A variable power optical system, including a fixed negative first lens group, a second positive lens group and a third positive lens group, wherein the first lens group includes a deflecting element arranged to bend an optical path, and when d12w denotes a distance between an image side principal point of the first lens group and an object side principal point of the second lens group at a short focal length end, d12t denotes a distance between the image side principal point of the first lens group and the object side principal point of the second lens group at a long focal length end, fw denotes a focal length of the optical system at the short focal length end, ft denotes a focal length of the optical system at the long focal length end, and f1 denotes a focal length of the first lens group, the optical system satisfies: 2.5<(d12w/d12t)/|?{square root over (fw×ft)}/f1|<4.0.

Abstract: A zoom lens includes a first lens unit having a positive refractive power and arranged closest to an object side. 0.50<Ym5/Yw30<1.00 is satisfied at a predetermined zoom position except for a wide-angle end and a telephoto end where Yw30 denotes an image height that provides a relative illumination of 0.3 at the wide-angle end, and Ym5 denotes an image height that provides the relative illumination of 0.05 at a predetermined zoom position except for a wide-angle end and a telephoto end.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group. The second lens group includes a positive lens element, and two negative lens elements. The following conditions (1) and (2) are satisfied: 2.0<|VD1t?VD1w|/(ft/fw)<3.4??(1), and 0.89<|m2w/m3w|??(2), wherein VD1t and VD1w designate the distances, at the long and short focal length extremities, from the image-side surface of the lens element provided closest to the image side within the first lens group to the object-side surface of the positive lens element provided closest to the object side within the second lens group; ft and fw designate the entire focal length of the zoom lens system at the long and short focal length extremities; and m2w and m3w designate the lateral magnification of the second and third lens groups at the short focal length extremity when focused on an object at infinity.

Abstract: A zoom lens system of the present invention has a plurality of lens units each composed of at least one lens element and, in order from the object side to the image side, comprises: a first lens unit having negative optical power and composed of two lens elements; a second lens unit having positive optical power; and a third lens unit having positive optical power, wherein in zooming from a wide-angle limit to a telephoto limit during image taking, the individual lens units are moved along an optical axis such that an interval between the first lens unit and the second lens unit should decrease and that an interval between the second lens unit and the third lens unit should increase, so that magnification change is achieved, and wherein on the image side relative to the second lens unit, an aperture diaphragm is arranged that moves along the optical axis integrally with the second lens unit during zooming.

Abstract: An embodiment of this invention provides a zoom lens, which comprises, in order from an object side to an image-forming 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. Further, the zoom lens satisfies the following conditions: (1) DG1/fw>0.72; (2) DG2/fw<0.72; and (3) TTL/fw<7.0, wherein fw is the focal length of the optical zoom lens at a wide-angle end, DG1 is the thickness of the first lens group, DG2 is the thickness of the second lens group, and TTL is the total thickness of the zoom lens, i.e., the distance between the object side of the first lens group and an image-forming plane of the zoom lens.

Abstract: In a zoom lens, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having the positive refractive power are disposed from an object side to an image side; and in a phase of variable magnification from a wide-angle end to a telescopic end, the first lens group is moved and the second lens group is moved to the object side such that an air interval between the first lens group and the second lens group is decreased and an air interval between the second lens group and the third lens group is increased.

Abstract: A zoom lens includes, in order from an object side to an image side: first, second and third lens groups having a negative refractive power, a positive refractive power and a positive refractive power, respectively. The first lens group includes a single compound aspheric lens formed of a spherical glass lens having a negative refractive power and a resin lens having a positive refractive power and an image side surface thereof is aspheric, and the conditional expressions (1) to (4) are satisfied f11/fw<?1.8,??(1) 1.55<n11,??(2) 55<?11, and??(3) G1r1<?16.5,??(4) where f11 and fw are focal lengths of the spherical glass lens and the whole lens system at a wide-angle end, respectively, n11 and ?11 are a refractive index and an Abbe number, respectively, of the spherical glass lens at the d-line, and G1r1 is a radius of curvature of an object side surface of the spherical glass lens.

Abstract: An optical system for observation of a front-direction object and a substantially-lateral-direction object includes, in order from the front-direction-object side, a front group with a negative refracting power having a reflecting/refracting optical element, an aperture stop, and a rear group with a positive refracting power having a moving lens component movable along the optical axis. The reflecting/refracting optical element has a first face formed on the front-direction-object side, a second face formed on the image side, and a third face formed as a transmitting surface between the first face and the second face. The first face has a first transmitting surface formed with the optical axis being at a center thereof and a first reflecting surface annularly formed around the first transmitting surface and directed toward an image side.

Abstract: A zoom lens system of the present invention has a plurality of lens units each composed of at least one lens element and, in order from the object side to the image side, comprises: a first lens unit having negative optical power and composed of two lens elements; a second lens unit having positive optical power; and a third lens unit having positive optical power, wherein in zooming, the lens units are moved such that an interval between the first lens unit and the second lens unit should decrease and that an interval between the second lens unit and the third lens unit should increase, so that magnification change is achieved, and wherein the condition is satisfied: 1.5<LT/(Ir×Z)<2.6 where, Z=fT/fW>4.

Abstract: A zoom lens system includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, wherein the first through third lens groups are arranged sequentially from an object side. When the zoom lens system is zoomed from a wide angle position to a telephoto position, an interval between the first lens group and the second lens group decreases and an interval between the second lens group and the third lens group increases. The first lens group comprises three lenses. An imaging apparatus includes the zoom lens system.

Abstract: A zoom lens includes a negative first lens-group, a positive second lens-group, and a positive third lens-group, sequentially arranged from the object side. The focal length magnification of the zoom lens is changeable by changing a distance between the lens-groups. The first lens-group is composed of a negative first lens, the image side of which is concave, and a positive second lens that is an aspheric plastic lens. The second lens-group is composed of a cemented lens and a meniscus-form fifth lens having a convex surface facing the object side. The cemented lens is composed of a double-convex-form positive third lens and a double-concave-form negative fourth lens. The third lens-group is composed of a positive sixth lens, which is a single lens. Formula (1) about focal length fG2 of the second lens-group and focal length fw of the entire system at wide end is satisfied: 1.10<fG2/fw<1.33??(1).

Abstract: A zoom lens system of the present invention has a plurality of lens units each composed of at least one lens element and, in order from the object side to the image side, comprises: a first lens unit having negative optical power and composed of two lens elements; a second lens unit having positive optical power; and a third lens unit having positive optical power, wherein in zooming, the lens units are moved such that an interval between the first lens unit and the second lens unit should decrease and that an interval between the second lens unit and the third lens unit should increase, so that magnification change is achieved, and wherein the condition is satisfied: 1.5<LT/(Ir×Z)<2.6 where, Z=fT/fW>4.

Abstract: An image lens system includes a first lens group that includes a first and a second lens, a movable second lens group that includes a third and a fourth lens, and a third lens group that includes a fifth lens. The image lens system satisfies the formulas: 2.1?Lw/(a*Y)<2.5; 1.9?|Fp|/F1|?2.2; and 0.6?|Fp2/F2|?0.7, where “Lw” represents the overall length of the image lens system in the wide angle state, “a” represents the ratio of the effective focal length of the image lens system in the telephoto state to that in the wide angle state, “Y” represents the maximum height of image that the image lens system generates, “Fp1” and “Fp2” represents the effective focal lengths of the second and the fourth lenses, “F1” and “F2” represents the effective focal lengths of the first and the second lens groups.

Abstract: A zoom lens system of the present invention has a plurality of lens units each composed of at least one lens element and, in order from the object side to the image side, comprises: a first lens unit having negative optical power and composed of two lens elements; a second lens unit having positive optical power; and a third lens unit having positive optical power, wherein in zooming, the lens units are moved such that an interval between the first lens unit and the second lens unit should decrease and that an interval between the second lens unit and the third lens unit should increase, so that magnification change is achieved, and wherein the condition is satisfied: 1.5<LT/(Ir×Z)<2.6 where, Z=fT/fW>4.

Abstract: Various embodiments provide an optical system including a first lens group having a plurality of lenses; a second lens group having a plurality of lenses, the second lens group being disposed adjacent the first lens group; a third lens group having a plurality of lenses, the third lens group being disposed adjacent the second lens group; and a detector disposed behind the third lens group. A pupil of the optical system is located external to the first lens group, the second lens group and the third lens group. The second lens group is movable respective to the first lens group and the third lens group so as to convert a configuration of the optical system between a narrow field of view (NFOV) configuration and a wide field of view (WFOV) configuration.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit having a negative refractive power and a second lens unit having a positive refractive power. A distance between the first lens unit and the second lens unit varies during zooming. The first lens unit includes, in order from the object side to the image side, a negative lens and a positive lens of which an object-side lens surface has a convex shape. An Abbe number of a material of the positive lens of the first lens unit, a focal length of the first lens unit, a distance between an image-side lens surface of the first lens unit and an object-side lens surface of the second lens unit at a telephoto end, and focal lengths of the entire zoom lens at a wide-angle end and the telephoto end are appropriately set.