Abstract: A first lens group includes a plano-concave and negative first lens, a catoptric element having a flat object side surface and a flat image side surface, and a first cemented lens, for example. Here, the first cemented lens includes a negative second lens and a positive third lens in order from an object side. A second lens group includes an aperture stop and a positive second cemented lens, for example. The second cemented lens includes a positive fourth lens, a negative fifth lens, and a positive sixth lens in order from the object side. A zoom lens satisfies a conditional expression 1.59<n21<2.20, assuming that a value n21 indicates refractive index of the fourth lens on a side closest to an object in the second lens group.

Abstract: A zoom lens includes, in order from an object side in 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, a fifth lens group having a positive refractive power, and an aperture stop arranged between the third lens group and the fourth lens group, an interval between the first lens group and the second lens group being increased, an interval between the second lens group and the third lens group being varied, an interval between the third lens group and the fourth lens group being decreased, and an interval between the fourth lens group and the fifth lens group being decreased when changing a magnification from a wide-angle end to a telephoto end.

Abstract: A zoom lens includes, in order from the object side to the image side along its optical path, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power and including a prism reflecting member, 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, wherein the distances between the lens units vary during zooming from the wide angle end to the telephoto end, the first lens unit and the third lens unit are located closer to the ray incidence side at the telephoto end than at the wide angle end, the position of the second lens unit is fixed during zooming from the wide angle end to the telephoto end.

Abstract: A zoom lens substantially consists of, in order from the object side, a positive first lens group, a negative second lens group, a positive third lens group, a positive fourth lens group, and a negative fifth lens group. When varying magnification, the distances between adjacent lens groups are changed, while all of the lens groups are moved with respect to an image formation position. If fw represents the focal length of the entire lens system at the wide angle end, f4 represents the focal length of the fourth lens group, F5 represents the focal length of the fifth lens group, and ?5T is an image formation magnification of the fifth lens group when focusing on infinity at the telephoto end, formula (J): 0.50<fw/f4<0.65, formula (K): ?0.32<fw/f5<?0.15, and (C): ?6.0<1?(?5T)2<?2.5 are simultaneously satisfied.

Abstract: A zoom lens includes: a first lens group having a negative power; and a second lens group having a refractive power, in this order from an object side. The zoom lens satisfies the following conditional formulae: 1.0<D2g/D1g<1.6, 0.08<D2t/ft<0.19, 1.15?ft/|f1|<1.8, and 1.1<ft/f2<1.9, wherein D1g is the distance from a most object side lens surface to a most image side lens surface within the first group, D2g and D2t are the distance from a most object side lens surface to a most image side lens surface within the second group and the distance between an object side partial second lens group and an image side partial second lens group when focused on infinity at a telephoto end, respectively, ft is the focal length of the entire system at the telephoto end, and f1 and f2 are the focal lengths of the first group and the second group, respectively.

Abstract: A zoom lens includes a rear lens group having a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, an aperture stop, and a rear lens group having a plurality of lens units in this order from an object side to an image side, wherein the interval between the lens units adjacent to each other varies at the time of zooming, the first lens unit is fixed at the time of zooming, the first lens unit includes a first lens subunit having a negative refractive power, which is fixed at the time of focusing and a second lens subunit having a positive refractive power, which moves at the time of focusing at the time of focusing in this order from the object side to the image side, and the rear lens group includes a lens unit moving in a direction of an optical axis so that an imaging magnification at a telephoto end is larger than an imaging magnification at a wide-angle end.

Abstract: A zoom lens substantially consists of, in order from the object side, a positive first lens group, a negative second lens group, a positive third lens group, a positive fourth lens group, and a negative fifth lens group. When varying magnification, the distances between adjacent lens groups are changed, while all of the lens groups are moved with respect to an image formation position. If ?5T represents the image formation magnification of the fifth lens group when focusing on infinity at the telephoto end, fw represents the focal length of the entire lens system at the wide angle end, and f3 represents the focal length of the third lens group, formula (Ca): ?5.00?1?(?5T)2??3.30 and formula (H): 0.10<fw/f3<0.50 are satisfied.

Abstract: Provided is a zoom lens, comprising, in order from an object side to an image side: first to fifth lens units having positive, negative, positive, positive, and negative refractive powers, respectively. During zooming, the first, third, and fifth lens units are immovable, and the second and fourth lens units are moved. The fifth lens unit includes a partial unit (L5n) having a negative refractive power, and a partial unit (L5p) having a positive refractive power. An entire lens length (TL), a focal length (ft) of an entire system at a telephoto end, a focal length (f2) of the second lens unit, a focal length (f4) of the fourth lens unit, and a focal length (f5n) of the partial unit (L5n) are set appropriately.

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: The zoom lens substantially consists of a positive first lens group fixed while changing magnification, a negative second lens group which moves from the object side to the image side while changing magnification, a positive third lens group which moves while changing magnification, and a positive fourth lens group which moves from the image side to the object side while changing magnification, and a positive fifth lens group fixed while changing magnification in this order from the object side. A floating system in which the third lens group and the fourth lens group move relative to each other while changing magnification is adopted. The image formation magnification rates of the combined lens group formed by the third lens group and the fourth lens group together and the second lens group simultaneously pass ?1× point while changing magnification from the wide angle end to the telephoto end.

Abstract: A zoom lens includes a frontmost lens unit, which is located closest to the object side and a plurality of lens units located closer to the image side than the frontmost lens unit. All the distances between adjacent lens units vary during zooming in the state in which the zoom lens is focused on an object at infinity. One of the plurality of lens units is a first focusing lens unit. During focusing from an object at infinity to an object at a short distance in a first shooting mode, only the first focusing lens unit moves. During focusing from an object at infinity to an object at a short distance in a second shooting mode, two lens units in the zoom lens move.

Abstract: A zoom lens includes, in order from an object side to an image 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 negative refractive power; and a fifth lens group having a negative refractive power. During zooming from a wide-angle end state to a telephoto end state, air spacing between the first and second lens groups increases, air spacing between the second and third lens groups decreases, spacing between the third and fourth lens groups changes, and spacing between the fourth and fifth lens groups changes. Thus, all the lens groups are moved in an optical axis direction. The zoom lens satisfies the following Conditional Expression (1). 1.0<?5w?4.0??(1) Here, ?5w is a lateral magnification of the fifth lens group at a wide-angle end.

Abstract: A zoom lens 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, 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, wherein the first lens unit is located closest to the object side, the fifth lens unit is located closest to the image side, during zooming from the wide angle end to the telephoto end, the first lens unit, the second lens unit, the third lens unit, and the fourth lens unit move, the fifth lens unit is stationary, and the distances between the lens units vary, the third lens includes a positive lens, and the zoom lens satisfies the following condition (1): 72<?3p<110??(1).

Abstract: A zoom lens includes in order from an object side: a first lens unit having a positive refractive power which does not move for zooming; a second lens unit having a negative refractive power which moves during zooming; a third lens unit having a positive refractive power which moves during zooming; and a fourth lens unit having a positive refractive power which does not move for zooming, the third lens unit moving to an image side and then to the object side for zooming from a wide angle end to a telephoto end, in which a focal length (f1) of the first lens unit, a focal length (f2) of the second lens unit, a focal length (f3) of the third lens unit, and a lateral magnification (?3w) of the third lens unit at the wide angle end when a ray enters from infinity are appropriately set.

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 substantially consists of, in order from the object side, a positive first lens group, a negative second lens group, a positive third lens group, a positive fourth lens group, and a negative fifth lens group. When varying magnification, the distances between adjacent lens groups are changed, while all of the lens groups are moved with respect to an image formation position. When focusing, only the fifth lens group is shifted. The fifth lens group has at least one negative lens and at least one positive lens.

Abstract: A projector for projecting light onto a projection surface includes a first group (1) with a negative meniscus, a second group (2) with positive refractive power, a third group (3) with a single lens, a fourth group (4) with a lens with positive refractive power, and a field lens (5) with positive refractive power, such that the light passes through the projection objective from the fourth to the first group. In order to be provide a high image quality with a small number of optical components and the smallest dimensions, the projector is configured so the common focal width of the fourth group (4) and the field lens (5) is smaller than twice the image circle diameter (9) of the projection objective and the maximum free diameter (8) is smaller than the overall focal width, and in particular smaller than 0.8 times the overall focal width of the projection objective.

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 focus lens unit having a negative refractive power, configured to move in focusing, and a final lens unit having a positive refractive power, disposed closest to the image side. The focus lens unit and the final lens unit are disposed so as to be adjacent to each other, each lens unit moves so that a distance between adjacent lens units changes in zooming, and a focal length of the final lens unit fimg, a focal length of the focus lens unit ff, and a focal length of an entire system at a wide-angle end fw are appropriately set.

Abstract: A zoom lens includes, in order from an object side to an image 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.

Abstract: A zoom lens includes: a first lens group having a positive refractive power and including a plurality of 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 negative refractive power and including one lens, and a fifth lens group having a positive refractive power and including one lens. The first through fifth lens groups are subsequently arranged from an object side. An interval between neighboring lens groups changes during zooming from a wide angle position to a telephoto position. The zoom lens satisfies the following inequality, 0.4?n1?n2?0.7, where “n1” denotes a refractive index of a first lens from the object side in the first lens group, and “n2” denotes a refractive index of the second lens from the object side in the first lens group.

Abstract: Including, in order from an object side: a first lens group having positive power; a second lens group having negative power; and a third lens group having positive power, each distance between respective lens groups varying upon zooming; the third lens group including, in order from the object side, a first sub-group having positive power, a second sub-group having positive power, a third sub-group having negative power, and a fourth sub-group having positive power, the first sub-group being movable along an optical axis for focusing, the third sub-group being movable in a direction including a component perpendicular to the optical axis, thereby correcting an image blur, and a given condition being satisfied, thereby providing a compact zoom lens having high optical performance with disposing a focusing lens and a vibration reduction lens in the same lens group, an optical apparatus equipped therewith, and a method for manufacturing the zoom lens.

Abstract: A variable-magnification projection optical system substantially consists of a negative first lens group that is disposed at the most enlargement-side position and is fixed during magnification change, a positive last lens group that is disposed at the most reduction-side position and is fixed during magnification change, and a plurality of lens groups that are disposed between the first lens group and last lens group and are moved during magnification change. The most enlargement-side lens group (the second lens group) of the lens groups that are moved during magnification change has a negative refractive power. Predetermined conditional expressions relating to a back focus of the entire system on the reduction side at the wide-angle end, a focal length of the entire system at the wide-angle end, a focal length of the second lens group and a focal length of the last lens group are satisfied.

Abstract: A variable-magnification projection optical system substantially consists of a negative first lens group that is disposed at the most enlargement-side position and is fixed during magnification change, a positive last lens group that is disposed at the most reduction-side position and is fixed during magnification change, and a plurality of lens groups that are disposed between the first lens group and last lens group and are moved during magnification change. The lens groups that are moved during magnification change substantially consist of three lens groups, wherein the most enlargement-side lens group is a negative lens group. Predetermined conditional expressions relating to a back focus of the entire system on the reduction side at the wide-angle end, a focal length of the entire system at the wide-angle end, a focal length of the last lens group, and a focal length of the first lens group are satisfied.

Abstract: A zoom lens includes, in order from an object side to an 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, a fourth lens unit having negative refractive power, and a fifth lens unit having positive refractive power. At least the first, second, and third lens units move during zooming so that the first lens unit is located closer to an object side than an image side, the second lens unit is located closer to the image side, and the third lens unit is located closer to the object side at a telephoto end than a wide-angle end. Movement, focal length, and positioning parameters of first to third lens units, during zooming from the wide-angle end toward the telephoto end, are appropriately set based on mathematical conditions.

Abstract: The imaging apparatus includes a focus lens, a front zoom lens disposed on a subject side of the focus lens, a rear zoom lens disposed on an image side of the focus lens, a focus drive unit configured to drive the focus lens, a zoom drive unit configured to drive the front and rear zoom lenses, a focus origin point detector provided in a movable range of the rear zoom lens, configured to detect a focus origin point of the focus lens, and a controller configured to control the focus drive unit and the zoom drive unit. When the controller loses track of a position of the focus lens, the controller drives the focus lens in accordance with a relative movement amount of the front and rear zoom lenses by the zoom drive unit to move the focus lens to the focus origin point.

Abstract: An image pickup apparatus includes a zoom lens and an image pickup element. The zoom lens includes a first positive lens unit, a first negative lens unit, a stop, and a second positive lens unit. For zooming, the first positive lens unit is stationary, the first negative lens unit moves, and the second positive lens unit moves. A position at a telephoto end of the first negative lens unit is on the image side of a position at the wide angle end. A position at a telephoto end of the second positive lens unit is on the object side of a position at the wide angle end. For focusing, the first positive lens unit is stationary. A first positive lens unit object-side system has a negative refractive power. A first positive lens unit image-side system has a positive refractive power. The image pickup apparatus satisfies predetermined conditional expressions.

Abstract: A zoom lens includes a negative lens unit arranged closest to an enlargement conjugate side among lens units having negative refractive power included in the zoom lens, at least one positive lens unit having positive refractive power arranged closer to the enlargement conjugate side than the negative lens unit, and a rear lens unit including at least one lens unit and arranged closer to a reduction conjugate side than the negative lens unit, wherein a distance between adjacent lens units is changed during zooming, a stop is arranged closer to the reduction conjugate side than the negative lens unit, the rear lens unit includes at least one positive lens, and the positive lens satisfies a predetermined condition.

Abstract: Provided are an ocular zoom optical system which has a wide apparent field of view even on a low power side and in which aberrations are favorably corrected while a sufficient eye relief is secured over the entire zoom range, and an optical instrument including the ocular zoom optical system. The ocular zoom optical system 3 includes, in order from the object side: a first lens group G1 having a negative refractive power; a second lens group G2 having a positive refractive power; and a third lens group G3 having a positive refractive power and at least one aspheric surface. An intermediate image I? is formed between the first lens group G1 and the second lens group G2. During zooming, the third lens group G3 is fixed on the optical axis, and the first lens group G1 and the second lens group G2 are moved in directions opposite to each other with the intermediate image I? interposed therebetween.

Abstract: The endoscope objective lens is configured such that focusing from the farthest object to the nearest object is achieved by moving at least one lens group other than the most object-side lens group along the optical axis. One of the at least one lens group to be moved during focusing is a negative lens group. The one negative lens group that is moved during the focusing consists of a cemented lens that is formed by a positive lens and a negative lens cemented together in this order from the object side. The cemented surface of the cemented lens is oriented such that the concave surface faces the object side. Given conditional expressions are satisfied.

Abstract: An imaging assembly for the viewing, imaging, and analysis of chemiluminescent or bioluminescent samples in gels or other substrates, in which an adjustable camera and lens module having a prime or fixed lens or a focusing lens is moved to change the field of view by shifting the focal plane of the camera and lens module. The imaging assembly can also include a mirror to bend or fold the optical path between the camera and lens module and the target area having a sample, in which the mirror can move in the same vertical direction as the camera and lens module. Further, the camera and lens module can be configured to more move in a diagonal direction relative to the location of the imaging target area. The imaging assembly can further have a duct system adaptable to adjust with the movement of the camera and lens module.

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, including, in order from object side, a positive first unit, a negative second unit, a positive third unit, a negative fourth unit, and a positive fifth unit. The first unit includes, in order from object side, a negative first sub unit which does not move for focusing, a positive second sub unit which moves during focusing, and a positive third sub unit which does not move for focusing and includes a negative lens. 1.6<L2tm/L2t<1000.0; L2w/L3w<1.0; and ?0.5<f2/f3<?0.05 are satisfied, where L2t represents an second-third unit interval at a telephoto end, L2tm represents second-third unit interval at a zoom position at which an interval between the third and fourth units is minimum, L2w represents second-third unit interval at a wide-angle end, L3w represents third-fourth unit interval at the wide-angle end, and f2 and f3 represent focal lengths of the second and third units, respectively.

Abstract: Provided is a zoom lens in which a variation in aberration with respect to a temperature change is small and excellent optical characteristics can be easily obtained. The zoom lens includes multiple lens units in which a distance between adjacent ones of the multiple lens units changes for zooming. When an average value of a change in refractive index with respect to a temperature change within a temperature range of from 0° C. to 40° C. is ?Nav, at least one lens unit L of the multiple lens units includes multiple optical elements A made of materials satisfying a conditional expression: |?Nav|>5.0×10?5. When an anomalous partial dispersion ratio for a g-line and an F-line is ??gF??, at least one optical element A? of the multiple optical elements A satisfies a conditional expression: |??gF??|>0.0272.

Abstract: A zoom lens includes: a first lens group having a positive refractive power which is fixed while changing magnification; two or more movable lens groups that move independently from each other while changing magnification; and a final lens group having a positive refractive power which is fixed while changing magnification, provided in this order from an object side. The zoom lens satisfying Conditional Formula (1) below: 1.30<h/(Yimg·tan ?)<2.

Abstract: A zoom lens comprises in order from an object side a first lens unit having a positive refractive power. The first lens unit consist one positive lens. The zoom lens satisfies the following conditional expressions (1) and (2). Fno(W)<2.7??(1) 3.1<ft/fw where, Fno(W) denotes an F-number of the zoom lens at a wide angle end, ft denotes a focal length at a telephoto end of the overall zoom lens system, and fw denotes a focal length at the wide angle end of the overall zoom lens system.

Abstract: A zoom lens includes a first lens unit, a second lens unit, a third lens unit and a fourth lens unit that includes a 41 lens group and a 42 lens group. The 41 lens group includes a 411 lens group and a 412 lens group. A lens surface on a most image side of the 411 lens unit has a shape convex to the image side and a lens surface on the most object side of the 412 lens unit has a shape concave to the object side. A curvature radius r411 of the lens surface on the most image side of the 411 lens unit, a curvature radius r412 of the lens surface on the most object side of the 412 lens unit, and lateral magnification ?3w of the third lens unit at a wide-angle end are respectively appropriately set.

Abstract: In a zoom lens including a positive first lens unit, negative second lens unit, positive third lens unit, and positive fourth lens unit, the fourth lens unit includes a 41 lens group, a 42 lens group, and a 43 lens group. the lateral magnification of the third lens unit at a wide-angle end when an infinite object is focused, the focal length of the fourth lens unit, the lens configuration length of the fourth lens unit, the air interval between the 41 and 42 lens groups, the air interval between the 42 and 43 lens groups, the focal length of the 42 lens group, the average values of the Abbe constants and partial dispersion ratios of positive lens of the 42 lens group, the average values of the Abbe constants and partial dispersion ratios of negative lenses of the 42 lens group, and the like are appropriately set.

Abstract: A zoom lens, including, in order from object side to image side: a positive first lens unit which does not move during zooming; a negative second lens unit for zooming; a positive third lens unit for zooming; a negative fourth lens unit which moves during zooming; and a positive fifth lens unit which does not move during zooming, in which: 0.6<|?3F|<1.0, ?4.0<f4/f3<?1.0, and 20<L2w/L3w<300 are satisfied, where ?3F is a lateral magnification of the third lens unit at a position at which a lateral magnification of the second lens unit becomes ?1; f3 and f4 are respectively focal lengths of the third and fourth lens units; L2w is a gap between the second and third lens units at a wide angle end; and L3w is a gap between the third and fourth lens units at the wide angle end.

Abstract: A positive first lens group that is fixed during magnification change, a negative second lens group that is movable during magnification change, a positive third lens group that is movable during magnification change, a positive fourth lens group that is movable during magnification change, and a positive fifth lens group that is fixed during magnification change are arranged in this order from the enlargement side. The system is telecentric at the reduction side. Conditional expression (1) is satisfied: L/Im?<15.0??(1), where L is a distance along the optical axis from the most enlargement-side lens surface to the most reduction-side lens surface when the projection distance is infinity, and Im? is a maximum effective image circle diameter at the reduction side.

Abstract: A zoom lens includes a positive first lens group fixed during zooming, a negative second lens moved to the image side upon zooming from the wide angle end to the telephoto end, a negative third lens group for image plane correction during zooming, and a positive fourth lens group fixed during zooming. The first lens group is composed of a negative first lens group front group, a positive first lens group middle group, and a positive first lens group rear group, disposed in order from the object side. The first lens group front group is composed of two negative lenses and one positive lens, disposed in order from the object side. Focusing is performed by moving only the first lens group middle group in an optical axis direction. The zoom lens satisfies a predetermined conditional expression.

Abstract: A zoom lens substantially consists of, in order from the object side, a positive first lens group, a negative second lens group, a positive third lens group, a positive fourth lens group, and a negative fifth lens group. When varying magnification from the wide angle end to the telephoto end, a distance between the first lens group and the second lens group is always increased, a distance between the second lens group and the third lens group is always decreased, a distance between the third lens group and the fourth lens group is always decreased, and a distance between the fourth lens group and the fifth lens group is changed, while all of the lens groups are moved with respect to an image formation position. Formulas (Ca): ?5.00?1?(?5T)2<?2.5 and (D): 0.10<fw/f1<0.25 are satisfied.

Abstract: A zoom lens includes a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, third lens unit having a positive refractive power, a fourth lens unit having a negative refractive power, a fifth lens unit having a positive refractive power, and an aperture stop disposed between the second lens unit and the third lens unit. At the time of zooming, the aperture stop moves and the fifth lens unit is fixed. At the time of zooming from a wide angle end to a telephoto end, a distance between the first lens unit and the second lens unit widens, a distance between the second lens unit and the third lens unit narrows, a distance between the third lens unit and the fourth lens unit fluctuates, and a distance between the fourth lens unit and the fifth lens unit fluctuates.

Abstract: A zoom lens includes: a first lens group having a negative power; and a second lens group having a positive power, in this order from an object side. The first lens group includes a first lens having a negative power and a second lens having a positive power. The zoom lens satisfies conditional formulae 1.6<|f1|/fw<2.5 (1); 1.6<f2/fw<2.4 (2); 0.32<d2/fw<0.60 (3); 2.5<ft/fw<4.5 (4); 1.56<nd2<1.66 (5); and ?d2<33 (6), when f1: the focal length of the first lens group, f2: the focal length of the second lens group, fw: the focal length of the entire system at the wide angle end, d2: the distance between the first and second lenses along an optical axis, ft: the focal length of the entire system at the telephoto end, nd2: the refractive index of the second lens at the d line, and ?d2: the Abbe's number of the second lens at the d line.

Abstract: A first lens group having positive refractive power and a second lens group are arranged in this order from an object side, and only the first lens group moves in the optical axis direction while focusing. The first lens group substantially consists of a positive 1-1 lens, a positive 1-2 lens, a positive 1-3 lens, a negative 1-4 lens, an aperture stop, a negative 1-5 lens, a positive 1-6 lens, and a positive 1-7 lens. The 1-3 lens and the 1-4 lens are cemented to each other, and the 1-5 lens and the 1-6 lens are cemented to each other. The second lens group substantially consists of a negative 2-1 lens and a positive 2-2 lens. Only the first lens group moves in the optical axis direction while focusing.

Abstract: A zoom lens comprising, 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, a fourth lens unit having a negative refractive power, and a fifth lens unit having a positive refractive power. Each distance between the first lens unit and the second lens unit, between the third lens unit and the fourth lens unit, and between the fourth lens unit and the fourth lens unit at the telephoto end is longer than at the wide angle end, and a distance between the second lens unit and the third lens unit at the telephoto end is shorter than at the wide angle end, and the following conditional expressions are satisfied. 2<mg3t/mg3w<6 1.2<mg5t/mg5w<4 0.02<f5/ft<0.

Abstract: In a zoom lens system, an optical apparatus, and a manufacturing method, there are provided, in order from an object side: a first lens group having positive power, a second lens group having negative power, a third lens group having positive power, a fourth lens group having negative power, a fifth group having positive power, and an aperture stop disposed to an image side of the second lens group. Upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens and second lens groups increases, a distance between the second and third lens groups decreases, a distance between the third and fourth lens groups varies, and a distance between the fourth and fifth lens groups varies. With given conditions being satisfied, high optical performance with suppressing variation in aberrations are achieved.

Abstract: A zooming optical system that is compact and has high zooming ratio and superb optical performance, optical system and a method for manufacturing the zooming optical system, are provided. The zooming optical system includes, in order from an object along the optical axis, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having negative refractive power, and upon zooming from a wide angle end state to a telephoto end state, a distance between the first lens group G1 and the second lens group G2, a distance between the second lens group G2 and the third lens group G3, a distance between the third lens group G3 and the fourth lens group G4, and a distance between the fourth lens group G4 and the fifth lens group G5, being respectively varied.

Abstract: The zoom lens includes a front unit including a first positive lens unit and a second positive or negative lens unit, a reflective mirror and a rear unit including two or more lens units. During zooming, the reflective mirror is not moved, and the first lens unit and at least two lens units of the rear unit are moved. When the zoom lens is retracted into a body of an image pickup apparatus, at least one of rotation of the reflective mirror such that a normal line thereto is brought closer to parallel to an optical axis of the rear unit and axial movement thereof in a direction of the optical axis of the rear unit is performed. The front unit is moved into a space formed by the at least one of the rotation and the axial movement. Conditions of 10.5<ft/|fn|<30.0 and 0.80<(Lf?L)/Lm<1.30 are satisfied.

Abstract: A zoom lens includes, in order from object side to image side, a positive first lens unit, a negative second lens unit, a positive third lens unit, a negative fourth lens unit, and a rear lens unit including, in order from object side to image side, a positive first lens subunit, a negative second lens subunit, and a positive third lens subunit. The relationship between the combined focal length of the first and second lens units at wide-angle end, the combined focal length of the third lens unit and the lens units on the image side of the third lens unit at wide-angle end, the focal length of the second lens subunit, and the focal length of the rear lens unit at telephoto end is appropriately set.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit of a positive refractive power, a second lens unit of a negative refractive power, a third lens unit of a positive refractive power, a fourth lens unit of a positive refractive power, and a fifth lens unit, the second and fourth lens units being moved during zooming, a distance between the first and second lens units increasing at a telephoto end in comparison with a wide-angle end, wherein the fifth lens unit includes a first lens subunit of a negative refractive power, and a second lens subunit of a positive refractive power, the first lens subunit is moved to have a component perpendicular to an optical axis to change an image-forming position, and a condition 0.5<|(1??5n)×?5p|<2.0 is satisfied.