Abstract: A zoom lens and a photographing device including the zoom lens. The zoom lens 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, which are sequentially arranged in a direction from an object side to an image side, wherein the first lens group comprises a first lens that is biconcave and is closest to the object side. Accordingly, a compact and low-priced zoom lens having a high magnification may be manufactured.

Abstract: Composing a projection zoom lens with a first lens group disposed on the most magnification side and having a positive power, the lens group being fixed at the time of zooming, a final lens group disposed on the most reduction side and having a negative power, the lens group being fixed at the time of zooming, and a plurality of lens groups disposed between the first and final lens groups and moved at the time of zooming along an optical axis in association with each other for the zooming and correction of image plane shift arising from the zooming, in which the final lens group includes a lens having a positive power on the most reduction side.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group, in that order from the object side, wherein 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 increases. The second lens group includes a positive first sub-lens group and a negative second sub-lens group, in that order from the object side. The second sub-lens group is a negative single lens element serving as an image-stabilizer lens group which moves in directions orthogonal to the optical axis to change the imaging position to correct image shake.

Abstract: A zoom lens includes in order from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a negative refractive power, a fourth lens group having a positive refractive power, a fifth lens group having a positive refractive power, and a last lens group having a positive refractive power. At the time of zooming from a wide angle end to a telephoto end, the second lens group and the third lens group move, and one of the fourth lens group, the fifth lens group, and the last lens group moves.

Abstract: A zoom lens includes, 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, an aperture stop, a third lens unit having a positive refractive power, a fourth lens unit having a negative refractive power, and a fifth lens unit having a positive refractive power. During zooming, the first lens unit and the aperture stop do not move and the second, third, and fourth lens units move along different loci. Lateral magnifications of the second lens unit at a wide angle end and at a telephoto end and lateral magnifications of the third lens unit at the wide angle end and at the telephoto end are each appropriately set based on predetermined mathematical conditions.

Abstract: A zoom lens system, 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; a fourth lens unit having positive optical power; and a fifth lens unit having negative optical power, wherein the first lens unit is composed of only optical elements having optical power, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, at least the first lens unit is fixed with respect to an image surface, and the condition: 0.7<|M4G/M5G|<11.0 (M4G: an amount of movement of the fourth lens unit with respect to the image surface in zooming, M5G is an amount of movement of the fifth lens unit with respect to the image surface in zooming) is satisfied.

Abstract: A zoom lens system comprising: a positive first lens unit; a negative second lens unit; a positive third lens unit; a fourth lens unit; and at least one subsequent lens unit, wherein the subsequent lens unit(s) includes a negative lens unit, the first and third lens units are respectively composed of two or less lens elements and four or more lens elements, the first and second lens units move along an optical axis in zooming, and the conditions: 0.0<LGmax/LG2<1.5, 0.2<|f2/fW|, and 0.1<|fe/f2| (LGmax: a maximum value of an axial thickness of the subsequent lens unit(s), LG2: an axial thickness of the second lens unit, fW, f2, and fe: focal lengths of the entire system at a wide-angle limit, the second lens unit, and a negative lens unit located closest to the image side) are satisfied.

Abstract: A zoom lens includes, in order from an object side to an image side, first and third lens units having a positive refractive power, a second lens unit having a negative refractive power, and a rear lens group. The first lens unit is closer to the object side at a telephoto end than at a wide angle end. The second lens unit is closer to the image side at the telephoto end than at the wide angle end. A distance between the second lens unit and the third lens unit at the telephoto end, focal lengths at the wide angle end and the telephoto end, respectively, a focal length of the second lens unit, and an amount of movement of the second lens unit in an optical axis direction during zooming from the wide angle end to the telephoto end are appropriately set.

Abstract: Disclosed herein is a variable focal length lens system including: a first lens group having a positive refracting power; a second lens group having a negative refracting power; a third lens group having a negative refracting power; a fourth lens group having a positive refracting power; and a fifth lens group having a positive refracting power; all of the first to fifth lens groups moving, when a positional state of the variable focal length lens system changes from a wide angle end state to a telephoto end state; the fifth lens group being configured from a first sub lens group and a second sub lens group; and the variable focal length lens system satisfying the following expression (1): 0.5<Dsub/fw<0.

Abstract: A zoom lens system, 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; a fourth lens unit; and at least one subsequent lens unit, wherein the subsequent lens unit(s) includes a lens unit having negative optical power, the first lens unit is composed of two or less lens elements, the third lens unit is composed of four or more lens elements, the first lens unit and the second lens unit move along an optical axis in zooming, and the condition: 0<|fW/fe<2 (fe: a focal length of a lens unit having negative optical power and located closest to the image side in the entire system, fW: a focal length of the entire system at a wide-angle limit) is satisfied.

Abstract: A zoom lens includes first to fifth lens units arranged sequentially from object to image sides and having respective refractive powers. Compared to a wide-angle end, at a telephoto end, the distance between the first and second lens units, the distance between the third and fourth lens units, and the distance between the fourth and fifth lens units are increased, and the distance between the second and third lens units is decreased. Compared to the wide-angle end, at the telephoto end, the first lens unit is positioned closer to the object side. The first and second lens units each consist of a positive lens element and a negative lens element. The distances between the third and fourth lens units at the wide-angle and telephoto ends D34w and D34t and the focal length of the entire zoom lens at the wide-angle end fw are appropriately set.

Abstract: A zoom lens system, in order from an object side to an image side, comprising: a first lens unit having positive optical power; and a second lens unit having negative optical power, wherein the first lens unit is composed of two or less lens elements, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, at least the first lens unit is fixed with respect to an image surface, and the conditions: LT/fT<1.45 and 2.6<(fT/fW)×(tan(?W))2 (LT: an overall length of lens system at a telephoto limit, fT: a focal length of the entire system at the telephoto limit, fW: a focal length of the entire system at a wide-angle limit, ?W: a half view angle at the wide-angle limit) are satisfied.

Abstract: A zoom lens includes, from the object side to the image side, first to sixth lens units having positive, negative, positive, negative, positive, negative refracting powers. In zooming from the wide angle end to the telephoto end, the lens units are moved such that the distance between the first and second lens units increases, the distance between the second and third lens units decreases, the distance between the third and fourth lens units increases, and the distance between the fourth and fifth lens units decreases. In focusing from an infinitely distant object to a near object, the sixth lens unit is moved toward the image side. The distance between the rear principal point of the second lens unit and the front principal point of the rear lens group at the wide angle end, and the focal length of the rear lens group at the wide angle end are appropriately set.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group, in that order from the object side, wherein upon zooming from the short to long focal length extremities, 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 increases. The second lens group includes a positive first sub-lens group and a negative second sub-lens group, in that order from the object side. In at least part of the zooming range of the zoom lens system, the second sub-lens group and the third lens group each serves as a focusing lens group that is moved along the optical axis during a focusing operation.

Abstract: A zoom lens includes a fixed first lens group having a positive refracting power, a second lens group having a negative refracting power and movable along an optical axis, a fixed third lens group having a positive refracting power, a fourth lens group having a negative refracting power and movable along the optical axis, and a fixed fifth lens group, disposed in order from the object side to the image side. The following expressions are satisfied: 0.5<f1/(fw·ft)1/2<1.8 ?0.4<f3/f5<0.4 where f1, fw, ft, f3 and f5 are focal lengths of the first lens group, the entire lens system in a wide angle end state, the entire lens system in a telephoto end state, the third lens group and the fifth lens group, respectively.

Abstract: A zoom lens with a bent optical path comprising, 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 lens unit group having a positive refractive power as a whole. The first lens unit includes a reflecting member. The rear lens unit group includes three lens unit including, in order from the object side to the image side, a third lens unit having a positive refractive power, a fourth lens unit having a negative refractive power, and a fifth lens unit having a positive refractive power. The distances between the lens units change during zooming from the wide angle end to the telephoto end. The zoom lens satisfies the predetermined conditional expressions.

Abstract: A zoom lens including first to fifth lens units in order from an object side toward an image. The refractive powers of the first to the fifth lens units are positive, negative, positive, negative and positive, respectively. The distance between the first and the second lens units is increased at the time of zooming from the wide angle end to the telephoto end, and the distance between the second and the third lens unit is decreased at the time of zooming from the wide angle end to the telephoto end. The first lens unit and the fourth lens unit are fixed for the zooming. When M2 and M3 are the amounts of movement of the second lens unit and the third lens unit at the time of zooming from the wide angle end to the telephoto end, respectively, the conditional expression; 0.2<|M2/M3|<5.0 is satisfied.

Abstract: A zoom lens includes, in order from an object side along an optical axis, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a negative refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power, wherein with a change in a magnification from a wide-angle end to a telephoto end, an interval between the first lens group and the second lens group is increased, the interval between the second lens group and the third lens group is changed, the interval between the third lens group and the fourth lens group is decreased, the interval between the fourth lens group and the fifth lens group is decreased, and focusing is performed by the third lens group.

Abstract: A zoom lens includes sequentially from an object side, 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, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power. The zoom lens satisfies given conditions to implement a compact, wide angle, large aperture ratio zoom lens having excellent optical performance and compatible with solid state image sensors capable of recording full high vision images.

Abstract: A zoom lens includes sequentially from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, an aperture stop, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and fifth lens group. The zoom lens further satisfies given conditions.

Abstract: An aperture stop is arranged on the reduction side of the most reduction-side lens element in a fourth group; during zooming from the tele-end to the wide-end through a middle position that fulfills conditional formula 0.99<fm/(ft×fw)½<1.01, first and fifth groups remain stationary, the composite power of third and fourth groups is constantly positive, and the third and fourth groups move from the enlargement side to the reduction side, satisfying conditional formulae: 7<?TM3/|?TM2|, 7<?TW3/|?TW2|, 7<?TM4/|?TM2|, 7<?TW4/|?TW2|, 0.9<?TM4/?TM3<1.1, 0.9<?TW4/?TW<1.1 (ft, fm, and fw are the entire-system focal lengths at the tele-end, the middle position, and the wide-end; ?TM2-4 are the movement amounts of the second to fourth groups from the tele-end to the middle position; and ?TW2-4 are the movement amounts of the second to fourth groups from the tele-end to the wide-end).

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.

Abstract: A high-ratio 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 that order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, the first through fourth lens groups move along the optical axis of the zoom lens system while increasing the distance between the first and second lens groups, and decreasing the distance between the second and third lens groups. The following conditions are satisfied: 0.9<f3/f4<1.3 and ?3.85<f123t/f4<?3.04 wherein f3 designates the focal length of the third lens group, f4 designates the focal length of the fourth lens group, and f123t designates the combined focal length of the first, second and third lens groups when an object at infinity is in an in-focus state at the long focal length extremity.

Abstract: A zoom lens includes an imaging lens unit having a positive refractive power and provided nearest to an image-side end, and a focusing lens unit having a positive refractive power and provided on an object side of the imaging lens unit. A distance between the imaging lens unit and the focusing lens unit changes during zooming. The focusing lens unit moves during focusing. The imaging lens unit includes, at a position thereof nearest to an object-side end, a negative meniscus lens component that is concave on the object side thereof.

Abstract: A lens system comprises, on a side closest to an object, a first lens component having a positive refractive power and a second lens component having a positive refractive power in order from the object; and on a side closest to an image, a cemented lens constructed by cementing together a positive lens and a negative lens in order from the object; wherein the lens system satisfies the following conditional expressions: (n1+n2)/2>1.49 (?1+?2)/2>60 where n1 and ?1 denote a refractive index and an Abbe number of the first lens component at d-line, respectively, and n2 and ?2 denote a refractive index and an Abbe number of the second lens component at d-line, respectively.

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, and a rear lens group including lens units and as a whole having a positive refractive power. Distances between the lens units change during zooming. The second lens unit includes, in order from the object side to the image side, a negative lens component and a cemented lens including a negative lens component and a positive lens component. The second lens unit includes at least five lens components. A focal length f1 of the first lens unit, a focal length f2 of the second lens unit, a refractive index Ndp of the positive lens component of the cemented lens, and a refractive index Ndn of the negative lens component of the cemented lens are set appropriately.

Abstract: A zoom lens ZL, which is mounted on an electronic still camera 1 or the like, is composed of, in order from the object side, a first lens unit G1 having a positive refractive power, a second lens unit G2 having a negative refractive power, a third lens unit G3 having a positive refractive power, a fourth lens unit G4 having a negative refractive power, and a fifth lens unit G5 having a positive refractive power. The first lens unit G1 has, in order from the object side, a negative meniscus lens with a convex surface on the object side, and a positive lens, and the second lens unit G2 has, in order from the object side, a negative meniscus lens with a convex surface on the object side, a biconcave lens, and a positive lens. The zoom lens satisfies a condition of the following expression: 0.005<(?f2)×f3/(f12)<0.023, where f1, f2, and f3 are the respective focal lengths of the first, second, and third lens units G1, G2, and G3.

Abstract: A lens system having, in order from an object, at least a first lens group G1 having positive refractive power, and second to fourth lens groups G2 to G4, wherein the first lens group G1 includes a front portion lens group G1a, and a rear portion lens group G1b which is disposed to an image side of the front portion lens group G1a with an air distance therebetween, and performs focusing by shifting the rear portion lens group G1b in the optical axis direction, and the fourth lens group G4 includes, in order from the object, a negative lens and a positive lens (cemented negative lens L41), a negative lens L42, and an aperture stop S, and is fixed in the optical axis direction with respect to an image plane I upon zooming from a wide angle end state to a telephoto end state.

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 in order from an object side to an image side. The second and fourth lens units move during zooming, and the first and third lens units do not move for zooming. A focal length fw of the entire zoom lens at a wide-angle end, a focal length ft of the entire zoom lens at a telephoto end, a focal length f1 of the first lens unit, a focal length f2 of the second lens unit, and a focal length f4 of the fourth lens unit are appropriately set.

Abstract: An inner focus lens, 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; and a third lens unit having positive optical power, wherein the second lens unit is moved along an optical axis so that focusing from an infinite-distance object side to a short-distance object side is achieved, the first lens unit includes a bi-convex air lens, and the following conditions: 0.65<|f2/f|<5.00 and 0.5<f23/f1<9.0 (f2: a focal length of the second lens unit, f and f23: a focal length of the entire system and a composite focal length of the second and third lens units in an infinity in-focus condition, f1: a focal length of the first lens unit) are satisfied; an interchangeable lens apparatus; and a camera system are provided.

Abstract: A zoom lens system comprises, from an object side to an image side: a first lens unit; a second lens unit; a third lens unit; a fourth lens unit; and a fifth lens unit having positive refractive power, wherein: in zooming from a wide angle end to a telephoto end, the first, the second, the third, and the fourth lens units move so that an interval between the first and the second lens units is larger at the telephoto end than that at the wide angle end, an interval between the second and the third lens units is smaller at the telephoto end than that at the wide angle end, and a distance between the third and the fourth lens units varies; and a focal length of the first lens unit, and focal lengths of an entire system at the wide angle end and the telephoto end are appropriately set.

Abstract: A zoom lens including: 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, wherein the first lens group, the second lens group, the third lens group, and the fourth lens group are sequentially arranged in the order from an object side to an image surface side, while zooming from a wide-angle position to a telephoto position, the first lens group is moved in such a way that the distance between the first lens group and the second lens group is widened, the second lens group is moved along a trajectory convex toward the image surface side, the third lens group is moved from the image surface side to the object side, and the fourth lens group is moved along a trajectory convex toward the object side, and the zoom lens satisfies the following inequalities: vd1ave>68.2, and Nd1ave>1.

Abstract: A zoom lens includes, in order from an object side to an image side: a first lens unit having positive refractive power, which does not move for zooming, the first lens unit including a lens unit which moves for focusing; a second lens unit having negative refractive power for magnification variation; a third lens unit having negative refractive power, which moves for zooming; a fourth lens unit having positive refractive power, which moves for zooming; and a fifth lens unit having positive refractive power, which does not move for zooming, in which an interval between the fourth lens unit and the fifth lens unit becomes largest at a telephoto end, and lateral magnifications ?2w and ?2t of the second lens unit at a wide-angle end and at the telephoto end are respectively set appropriately.

Abstract: A projection lens system is constructed as a zoom lens system which is for use with a laser light source and performs magnification variation by moving at least a lens group along the optical axis, and the projection lens system fulfills the following conditional formula: (|AC(B2?G)|+|AC(R2?G)|)/(|AC(B1?G)|+|AC(R1?G)|)<0.8, where AC(B2?G) represents longitudinal chromatic aberration between the wavelengths ?B2 and ?G; AC(R2?G) represents longitudinal chromatic aberration between the wavelengths ?R2 and ?G; AC(B1?G) represents longitudinal chromatic aberration between the wavelengths ?B1 and ?G; and AC(R1?G) represents longitudinal chromatic aberration between the wavelengths ?R1 and ?G.

Abstract: A zoom lens 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, which are disposed in order from an object side to an image side and an aperture stop disposed between the second and third lens groups. When changing the magnification of the zoom lens from a short focal end to a long focal end, an interval between the first and second lens groups increases, an interval between the second and third lens groups decreases, and an interval between the third and fourth lens groups increases. The first and third lens groups are moved so as to be positioned at object side positions at the long focal end relative to positions at the short focal end. The third lens group has two positive lenses. Predetermined conditions of the positive lenses of the third lens group are 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, a third lens unit having a positive refractive power, and a rear lens group including one or more lens units. During zooming, the first lens unit moves along a locus convex towards the image side, and the second lens unit and the third lens unit move such that an interval between the first lens unit and the second lens unit becomes larger at a telephoto end than at a wide-angle end and an interval between the second lens unit and the third lens unit becomes smaller at the telephoto end than at the wide-angle end. The third lens unit includes a positive lens and a negative lens.

Abstract: A zoom lens optical system includes a first lens unit having a positive refractive index, a second lens unit which is arranged behind the first lens unit and has a negative refractive index, a third lens unit which is arranged behind the second lens unit and has a positive refractive index, and a fourth lens unit which is arranged behind the third lens unit and has a positive refractive index. An aperture is arranged within the third lens unit to prevent reduction of shutter speed due to large diameter of the zoom lens optical system.

Abstract: A zoom lens includes, in order from object side: a positive first lens unit which does not move for zooming; a zoom lens unit including at least two lens units which move for zooming; a stop; and a positive imaging lens unit which does not move for zooming, in which: the first lens unit includes, in order from object side, a positive first sub-lens unit, a negative second sub-lens unit, and a positive third sub-lens unit; the third sub-lens unit includes a movable positive sub-third sub-lens unit; the second sub-lens unit and sub-third sub-lens unit are driven to object side for focusing to a close object; and focal length f12 of the second sub-lens unit, focal length f13f of the sub-third sub-lens unit, drive amount ?×12 of the second sub-lens unit in focusing, and drive amount ?×13f of the sub-third sub-lens unit in focusing satisfy ?2.5<f12/f13f<?0.4 and 0.05<?×13f/?×12<5.0.

Abstract: A zoom lens and a photographing apparatus including the same. The zoom lens includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and an additional lens grouping having a positive refractive power, which are sequentially arranged from an object side, wherein the additional lens grouping comprises a third lens group having a positive refractive power.

Abstract: A zoom lens comprises in order from an object side, a first lens unit having a positive refractive power, and at the time of zooming from a wide angle end to a telephoto end, the first lens unit moves, and the zoom lens satisfies the following conditional expression (1). FNO(W)<1.64??(1) where, FNO(W) denotes an F-number of the zoom lens at the wide angle end.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power, a fourth lens unit having a positive or negative refractive power, and a fifth lens unit having a positive refractive power. In the zoom lens, the first lens unit is stationary during zooming. At least the second lens unit, the third lens unit, and the fifth lens unit move along an optical axis during zooming. Furthermore, in the zoom lens, a focal length of the entire zoom lens at a wide-angle end (fw) and an amount of movement of the second lens unit during zooming from the wide-angle end to a telephoto end (m2z) are appropriately set.

Abstract: A lens barrel is provided that includes a zoom optical system with an optical axis. The lens barrel also includes a first and a second lens group. The first lens group has a first curved part and a first straight part when viewed axially along the optical axis. The second lens group is axially and movably disposed relative to the first lens group and has a second curved part and a second straight part when viewed axially along the optical axis. The lens barrel is configured to change between an imaging state and a retracted state. In the imaging state, the first and second lens groups are aligned with one another along the optical axis. In the retracted state, the second lens group is disposed off center from the first lens group so that the first straight part is substantially parallel with the second straight part.

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 is provided that includes a compactly constructed focusing lens unit and that has a suppressed change in the image magnification at the time of movement of a focusing lens unit. The zoom lens system according to the present invention comprises a plurality of lens units and an aperture diaphragm arranged in the lens unit. The plurality of lens units include a focusing lens unit that is arranged on an object side relative to the aperture diaphragm and that moves in a direction along the optical axis at the time of focusing. Further, the zoom lens system satisfies at least one of the following conditions: (1) 1.2<|fF/fW|<6.0; and (2) 0.10<|fF/fT|<1.8 (here, fT/fW>3.0, fF: a focal length of the focusing lens unit, fT: a focal length of the entire system at a telephoto limit, fW: focal length of the entire system at a wide-angle limit).

Abstract: The optical system of the present invention includes a plurality of lens groups and a variable focus lens. Here, the variable focus lens satisfies the following condition: ?0.023?{(nA?1)/?A?(nB?1)/?B}/(nB?nA)?0.023 where nA and nB respectively denote the d-line refractive indices of a first medium and a second medium, and ?A and ?B respectively denote the d-line Abbe numbers of the first and second media. In addition, the plurality of lens groups moves in an optical axial direction; and the following condition holds: 0.8<|fao|/fw<5 where fao denotes the composite focal distance at the wide angle end of the part of the optical system, and fw denotes the focal distance of the entire system at the wide angle end.

Abstract: A lens module for capturing an object light-beam from an object-side is provided. The lens module includes a first lens group, a second lens group, a third lens group, a fourth lens group and a fifth lens group sequentially-arranged from the object-side to an image-side. The five lens groups respectively have at least one lens with positive refractive-power and at least one lens with negative refractive-power. The first, third and fifth lens groups are fixed groups, while the second and fourth lens groups are movable groups. An image apparatus including the lens module is also provided.

Abstract: A zoom lens comprises a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a rear group including at least two lens units and having a positive refractive power as a whole, in order from an object side to an image side. An interval of each of the lens units changes in a zoom operation, the rear group includes a lens unit R having a positive refractive power at the most image side, the lens unit R includes a lens having a concave surface at the image side and having an aspherical surface shape where a negative refractive power becomes stronger with increasing distance from an optical axis, and focal lengths f1, fR, and fw of the first lens unit, the lens unit R, and a whole system at a wide-angle end, respectively, are appropriately set.

Abstract: A zoom lens includes: a first lens group having a negative refractive power; a second lens group having a positive refractive power; a third lens group having a positive refractive power and including one piece of positive lens; and a fourth lens group having a negative refractive power, wherein the first, second, third, and fourth lens groups are sequentially disposed in an order from an object side to an image surface side of the zoom lens, all distances between adjacent lens groups change and the third lens group performs focusing while zooming from a wide angle position to a telephoto position, and a following condition is satisfied: 0<(L23W?L23T)/L23W<0.

Abstract: A zoom lens includes, in order from the object side, a first lens group having a positive refracting power and fixed in position, a second lens group having a negative refracting power and movable in a direction of an optical axis for zooming, a third lens group having a positive refracting power, and a fourth lens group movable in the direction of the optical axis. The first lens group includes three lenses including a negative lens, a positive lens and another positive lens disposed in order from the object side to the image side and satisfies 7.0<ft/fw<13.0 and??(1) 4.2<f1/fw<6.0??(2) where fw and ft are the focal lengths of the entire lens system in a wide angle end state and a telephoto end state, respectively, and f1 the focal length of the first lens group.

Abstract: A zoom lens includes, from the object side, a positionally-fixed first lens group having a positive refracting power, a second lens group having a negative refracting power and movable in an optical axis direction for zooming, a third lens group having a positive refracting power, and a fourth lens group movable in the optical axis direction. The first lens group includes a negative lens, a positive lens and another positive lens disposed in order from the object side and satisfies 15.0<ft/fw<31.0??(1) 7.0<f1/fw<13.0??(2) ?8.5<fL1/fw<?4.0??(3) where fw and ft are the focal lengths of the entire lens system in a wide angle end state and a telephoto end state, respectively, f1 is the focal length of the first lens group, and fL1 is the focal length of the negative lens of the first lens group.