Abstract: A zoom lens includes in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens unit. At a telephoto end, with respect to a wide angle end, a distance between the first lens unit and the second lens unit widens, and a distance between the second lens unit and the third lens unit narrows. At the time of zooming from the wide angle end to the telephoto end, a distance between the third lens unit and the fourth lens unit changes, and the zoom lens satisfies the following conditional expressions (1) and (2). 1.1<f2/f3<1.8??(1) ?0.5<?G1/?G2<0.

Abstract: A zoom lens includes a first lens group with a diffraction optical element and having positive refractive power, a second lens group having negative refractive power, a third lens group having negative refractive power, and a fourth lens group having positive refractive power, which are sequentially arranged from an object side to an image side. The second lens group and the third lens group are moved in accordance with zooming between a wide angle end and a telephoto end such that the second lens group is positioned to the object-most side at the wide angle end, and the third lens group is positioned to the image-most side at the telephoto end. At least one of the second lens group and the third lens group includes a negative lens satisfying the conditional expressions: 1.50<nd<1.75; 60.0<?d<75.0; and ?C,A??0.0015×?d<0.2550.

Abstract: A telescopic sight for a firearm includes a scope tube, first and second optical lenses, an eyepiece set and a linear power adjustment mechanism. The optical lenses are contained in the scope tube and configured to move along a longitudinal axis of the scope tube. The eyepiece set is coupled to one end of the scope tube. The linear power adjustment mechanism adjusts zooming power of the telescopic sight, and includes a zoom cam tube and a lever that are contained in the zoom cam tube. The lever is coupled to rotate the zoom cam tube. When actuated, the lever moves linearly along a direction parallel to the longitudinal axis of the scope tube such that a distance between the first and the second optical lenses along the longitudinal axis of the scope tube to change to adjust a zooming power of the telescopic sight.

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, and a rear lens group having a plurality of lens units at least one of which has positive refractive power. The distance between the first lens unit and the second lens unit is greater at a telephoto end than at a wide angle end. The first lens unit includes a positive lens and a negative lens. The rear lens group includes a lens unit R comprising a positive lens and a negative lens. The lens unit R has the highest zoom ratio among the lens units included in the rear lens group. The materials of the positive and negative lenses included in the first lens unit and in the lens unit R are selected appropriately based on predetermined mathematical conditions.

Abstract: A zoom lens assembly for monitor and a monitoring device are provided. The lens assembly comprises a first to a thirteenth lenses (L1-L13) arranged successively coaxially along the transmission direction of an incident light beam. The first, the eighth, the tenth and the twelfth lenses (L1, L8, L10 and L12) are biconvex positive lenses; the second, the ninth and the eleventh lenses (L2, L9 and L11) are falcate negative lenses; the third, the fourth, the sixth and the thirteenth lenses (L3, L4, L6 and L13) are falcate positive lenses; the fifth lens (L5) is a biconcave negative lens; and the seventh lens (L7) is a plano-concave negative lens. The second and the third lenses (L2 and L3) are closely adhered to each other, and the sixth and the seventh lenses (L6 and L7) are closely adhered to each other.

Abstract: A zoom lens system, in order from an object side to an image side, comprising: a negative first lens unit; a positive second lens unit; a negative third lens unit; and a positive fourth lens unit, wherein the first, second and third lens units move along an optical axis in zooming, the third lens unit moves along the optical axis in focusing, and the conditions: 2.5?|(1?(?3T)2)×(?4T)2|?7.0 and 0.5?BfW/fW?4.0 (?3T: a lateral magnification of the third lens unit at an infinite object point distance at the telephoto limit, ?4T: a lateral magnification of the fourth lens unit at an infinite object point distance at the telephoto limit, BfW: a back focal length of the zoom lens system at the wide-angle limit, fW: a focal length of the zoom lens system at the wide-angle limit) are satisfied.

Abstract: A zoom lens consists essentially of, in order from the object side, a positive first lens group, a positive second lens group, a negative third lens group, a negative fourth lens group, and a positive fifth lens group. During magnification change from the wide-angle end to the telephoto end, the first lens group and the fifth lens group are fixed relative to the image plane, and the second lens group, the third lens group, and the fourth lens group are moved along the optical axis direction to change distances between the lens groups.

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; a fourth lens group having a negative refractive power; and a fifth lens group having a positive refractive power, wherein the first to fifth lens groups are sequentially arranged in a direction from an object side, during zooming from a wide-angle position to a telephoto position, the first to fifth lens groups are moved, the third lens group includes a first positive lens, a second negative lens, and a third positive lens, and the second negative lens of the third lens group includes a concave object-side surface. The zoom lens may be part of an electronic apparatus, such as a photographing apparatus.

Abstract: A lens system, from an object side to an image side in the following order, at least includes: a fixed object-side lens group that is disposed closest to the object side; a first focusing lens group that moves during a focusing operation and includes a plurality of lenses; a second focusing lens group that moves during a focusing operation and includes a plurality of lenses; a wobbling lens group that has a smaller thickness on an optical axis than the thickness on the optical axis of the first focusing lens group and the thickness on the optical axis of the second focusing lens group, and vibrates in an optical-axis direction; and a fixed image-side lens group that is disposed closest to the image side.

Abstract: A green laser zoom beam expanding system, applied to the field of laser processing, and comprising a first lens, a second lens and a third lens (L1, L2, L3). The first lens and the third lens (L1, L3) are plane-convex plus lenses, and the second lens (L2) is a meniscus minus lens. The first lens, the second lens and the third lens (L1, L2, L3) respectively comprise a first surface and a second surface (S1, S2), a third surface and a fourth surface (S3, S4) as well as a fifth surface and a sixth surface (S5, S6). The radiuses of curvature of the first to sixth surfaces (S1, S2, S3, S4, S5, S6) are ?, ?29.8, 7.2, 1.6, ?, ?100. The center thickness of the first to third lenses (L1, L2, L3) is 2, 1, 4. The outer diameters of the first to third lenses (L1, L2, L3) are 10, 3, 34. Proportions of the refractive indexes to the Abbe numbers of the first to third lenses (L1, L2, L3) are 1.8:25, 1.48:68, and 1.8:25. An interval (d2) between the second surface and the third surface (S2, S3) is 8-28.

Abstract: A folded telephoto lens system may include multiple lenses with refractive power and a light path folding element. Light entering the camera through lens(es) on a first path is refracted to the folding element, which changes direction of the light on to a second path with lens(es) that refract the light to form an image plane at a photosensor. At least one of the object side and image side surfaces of at least one of the lens elements may be aspheric. Total track length (TTL) of the lens system may be 14.0 mm or less. The lens system may be configured so that the telephoto ration (TTL/f) is less than or equal to 1.0. Materials, radii of curvature, shapes, sizes, spacing, and aspheric coefficients of the optical elements may be selected to achieve quality optical performance and high image resolution in a small form factor camera.

Abstract: A zoom lens includes, in order from an object side toward an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens unit having a positive refractive power. The second lens unit, the third lens unit, and the fourth lens unit are moved during zooming. A position of the third lens unit at a telephoto end is closer to the object side than a position of the third lens unit at a wide-angle end. The focal length of the zoom lens at the wide-angle end, the difference in the position of the second lens unit on an optical axis between that at the wide-angle end and that at the telephoto end, and the focal length of the second lens unit are set appropriately.

Abstract: A zoom lens includes in order from an object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens group having a positive refractive power, and at the time of zooming, the first lens group is fixed, the second lens group moves, the third lens group moves, and the fourth lens group is fixed. The first lens group includes in order from the object side, a negative lens, a reflecting optical element, and a positive lens. The second lens group includes in order from the object side, an aperture stop, a positive lens, a cemented lens having a negative refractive power, and a positive lens. The cemented lens includes a positive lens and a negative lens.

Abstract: The present application provides a micromechanical (MEMS) based zoom lens system, for use in miniature device applications, such as miniature electronic imaging devices. The MEMS-based zoom lens system comprises at least four optical elements, or two Alvarez or Lohmann lenses, that are configured for passage of optical signals therethrough along an optical signal path. Each optical element is MEMS-driven and displaceable in a direction substantially transverse to the optical signal path. In use, the transverse displacement of the optical elements vary an overall focal length of the MEMS zoom lens system such as to provide an optical zoom function. A method of manufacturing a MEMS zoom lens system is also provided in a further aspect.

Abstract: A zoom lens includes, in order from an object side to an image side, a first, a second, a third, a fourth, a fifth, a sixth and a seventh lens units respectively having positive, negative, positive, negative, positive, negative and positive refractive powers. A distance between adjacent lens units change during zooming so that a distance between the fourth lens unit and the fifth lens unit at a telephoto end is shorter than the distance at a wide angle end and a distance between the fifth lens unit and the sixth lens unit at the telephoto end is longer than the distance at the wide angle end. And the fourth lens unit moves during focusing.

Abstract: An imaging lens includes a first lens group having positive refractive power; a second lens group having positive refractive power; and a third lens group having negative refractive power, arranged in this order from an object side to an image plane side. The first lens group includes a first lens having positive refractive power, a second lens having negative refractive power, and a third lens having positive refractive power. The second lens group includes a fourth lens having positive refractive power and a fifth lens having positive refractive power. The third lens group includes a sixth lens and a seventh lens. The first to fifth lenses have specific Abbe's numbers.

Abstract: The invention concerns an optical device and its application to generate an adjustable wave front deformation of a laser beam and thus to generate an adjustable beam spot geometry in the focal plane of laser optics. For this purpose, a device is provided which allows adjusting and modifying a laser beam in such a way that a beam spot, the shape of which can be adjusted continuously based on the original focal shape, is generated after focusing the beam, i.e. at least one dimension parameter of the shape of the beam spot has to be variable and adjustable so that the beam parameter product of the beam can also be modified without having to modify the focal position.

Abstract: The zoom lens is composed of: an object side lens group at least including, in order from an object side: a first lens group G1 having positive refractive power; and a second lens group G2 having negative refractive power; and an image focusing side lens group including, in order from the object side: a negative lens group A having negative refractive power; and a negative lens group B arranged by facing the negative lens group A across an air distance, having negative refractive power. In the zoom lens, focusing from infinity to a close object is achieved by moving just the negative lens group A toward an image focusing side to satisfy a conditional expression below: [Expression 1] ?1.80<?2t<?0.94??(1) (1??At2)×?Bt2<?4.

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: The invention provides a viewing optical system positioned between a viewing plane as a virtual plane and an eye point. The viewing optical system comprises, in order from the viewing plane side, a first lens and a filter.

Abstract: A wide-angle lens system is formed, sequentially from an object side, with a first group having a positive power, a second group having a negative power and a third group having a positive power, and at the time of focusing, only the second group is moved on an optical axis. The lens system satisfies conditional formulas of 0.3<BH1/T1<0.7 and 0.9<f3/f<1.8 (where BH1 is a distance from the final surface of the first group to a principal point position on the back side of the first group, T1 is a distance on the optical axis from a lens element surface of the first group closest to the side of the object to a lens element surface closest to the side of the image, f3 is the focal length of the third group and f is the focal length of the entire system).

Abstract: The zoom lens includes in order from an object side to an image side where N represents an integer equal to or more than 5, a first lens unit, a second lens unit, an (N?2)-th lens unit, an (N?1)-th lens unit and an N-th lens unit respectively having positive, negative, positive, negative and positive refractive powers. The (N?1)-th lens unit includes an image stabilizing lens unit. The conditions of 0.01<BldN/TDw<0.09 and 2.0<fN/fw<8.0 are satisfied where BldN represents a length of the N-th lens unit on the optical axis, TDw represents a distance on the optical axis between a most object side lens surface and a most-image side lens surface at a wide-angle end, fw represents a focal length of the entire zoom lens at the wide-angle end, and fN represents a focal length of the N-th lens unit.

Abstract: An image sensor includes a sensing device including a pixel array having a plurality of unit pixels, the sensing device being configured to generate pixel data in response to an incident light signal having information of an image of an object and information of an ambient light; an image data generation unit configured to generate image data corresponding to the object based on the pixel data; and an illuminance data generation unit configured to generate illuminance data corresponding to the ambient light based on the pixel data.

Abstract: A zoom lens apparatus with focus adjusting and an optical imaging device therewith are provided, wherein a combination of screw-driven ultra sonic motor and voice coil motor is adopted to drive different optical lens sets (25,61). For the ultra sonic motor, the screw motion of the rotor (23) is transformed into a simple rectilinear motion by providing a third tube (24) placed in the rotor (23) and radially fixed relative to the stator (22). Thus the zoom lens apparatus with focus adjusting produced with the combination can well maintain the stability of the optical axis, moreover, the combination of different driving methods integrates and makes better use of lens sets of different functions and hence simplifies the overall structure.

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 negative refractive power, a fifth lens group having a positive refractive power, and a sixth lens group having a negative refractive power. The zoom lens varies the interval between the lens groups to perform zooming; shifts the second lens group in a direction substantially orthogonal to the optical axis to correct image blur occurring with optical system vibrations; and satisfies given conditions, enabling a compact size and a high zoom ratio to be achieved while improving imaging performance.

Abstract: A camera lens module in which an optical system is configured to include five sheets of lenses is provided. In the camera lens module, first, second, third, fourth and fifth lenses are sequentially arranged from an object side, and the first lens performs a zooming operation while moving along an optical axis. Accordingly, the optical system is configured to include five sheets of lenses for performance of a zooming operation and to allow only the first lens to perform the zooming operation, so that it is possible to manufacture a high-resolution optical system in a compact size and to perform the zooming operation at a high speed.

Abstract: A fluidic lens may include an optical surface configured for deflection dominated by bending stress. An adjustable concentric load may be applied to the optical surface to cause a clear aperture region of the optical surface to deflect with generally spherical curvature. Adjusting the concentric load controls the radius of curvature. An adjustable uniformly-distributed load may be applied to the optical surface by fluid pressure that causes the clear aperture region to deflect with an aspheric shape. Adjusting the pressure controls the asphericity of curvature. First and second fluids having similar densities and different refractive indexes may be disposed on either side of a deflectable optical surface to help balance gravitational loading on either side of the optical surface, thereby reducing gravity-associated aberrations.

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 positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power, which are in this order from an object side, and a stop located between a most image-side surface of the second lens group and a most image-side surface of the third lens group. Distances between the lens groups change when magnification is changed from a wide angle end to a telephoto end. The third lens group consists of a positive lens, a cemented lens of a positive lens and a negative lens, a negative meniscus lens with its concave surface facing the object side, and a biconvex lens, which are in this order from the object side. Further, a predetermined conditional formula is satisfied.

Abstract: An imaging optical system includes, in order from the object side to the image side, a first lens element, a second lens element, a third lens element, an aperture stop, a fourth lens element, a fifth lens element, and a sixth lens element arranged along an optical axis. The first lens element has a concave image-side surface in the vicinity of the optical axis. The second lens element has a negative refractive power. The third lens element has a convex object-side surface in a vicinity of an optical axis. The fourth lens element has a convex object-side surface in the vicinity of the optical axis. The fifth lens element has a convex image-side surface in the vicinity of the optical axis. The sixth lens element is made of plastic and has a convex image-side surface in a vicinity of an outer circumference.

Abstract: The present application provides a micromechanical (MEMS) based zoom lens system, for use in miniature device applications, such as miniature electronic imaging devices. The MEMS-based zoom lens system comprises at least four optical elements, or two Alvarez or Lohmann lenses, that are configured for passage of optical signals therethrough along an optical signal path. Each optical element is MEMS-driven and displaceable in a direction substantially transverse to the optical signal path. In use, the transverse displacement of the optical elements vary an overall focal length of the MEMS zoom lens system such as to provide an optical zoom function. A method of manufacturing a MEMS zoom lens system is also provided in a further aspect.

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, and a third lens unit having positive refractive power, wherein at least the first to third lens units move during zooming from a wide-angle end to a telephoto end, and a focal length f2 of the second lens unit, a focal length ft of the entire zoom lens at the telephoto end, and a refractive index Nd2n of a lens having negative refractive power closest to the object side included in the second lens unit are appropriately set.

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 includes, in order from an object side, a first unit that does not move, a negative second unit which moves during zooming, a positive third unit which moves during zooming, a positive fourth unit which moves during zooming and focus adjustment, an aperture stop that does not move in an optical axis direction, and a positive fifth unit which does not move, wherein Zinf representing a zooming ratio of the entire zoom lens when focused on infinity, ?3winf and ?3tinf representing lateral magnifications of the third unit at the wide angle end and a telephoto end, respectively, when focused on infinity, ?4tinf and ?5tinf representing lateral magnifications of the fourth unit and the fifth unit, respectively, at the telephoto end when focused on infinity, and f3 and f4 representing focal lengths of the third unit and the fourth unit, respectively, satisfy predetermined conditional expressions.

Abstract: A zoom lens comprises a first lens unit G1 having a positive refractive power, a second lens unit G2 having a negative refractive power, and a plurality of lens units G3 and G4. Zooming from a wide angle end to a telephoto end is carried out by changing a distance between the lens units. One of the first lens unit G1 and the second lens unit G2 has, or both the first lens unit G1 and the second lens unit G2 have a specific arrangement.

Abstract: A zoom lens optical system includes, in order from an object side along an optical axis: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; a fourth lens group having negative refractive power; and a fifth lens group having positive refractive power, wherein upon zooming from a wide-angle end state to a telephoto end state, the first lens group being moved with respect to an image plane, a distance between the first lens group and the second lens group increasing, a distance between the second lens group and the third lens group decreasing, a distance between the third lens group and the fourth lens group varying, and a distance between the fourth lens group and the fifth lens group varying.

Abstract: The zoom lens includes at least five lens groups including first, second, third, fourth and fifth lens groups respectively having positive, negative, negative, positive and positive refractive powers. At least four movable lens groups are moved during zooming. At least two movable lens groups placed further on an image side than an aperture. C1 and C2 lens groups are moved so as to draw mutually different loci and such that a distance therebetween becomes maximum at a middle zoom position. The C1 and C2 lens groups are located further on a same side at the telephoto end than at a wide-angle end. At least one of D1 and D2 lens groups is moved during the zooming so as to be located further on an object side at a telephoto end than at the wide-angle end. A distance therebetween at the telephoto end becomes larger than that at wide-angle end.

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<0.9.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens unit having a positive refractive power. In the zoom lens, each lens unit moves to perform zooming. In addition, an amount of movement Mm of the fourth lens unit when zooming from a wide angle end to an intermediate zooming position, an amount of movement Mt of the fourth lens unit when zooming from the wide angle end to a telephoto end, a focal length fw of an entire system at the wide angle end, and focal lengths f3 and f4 of the respective third lens unit and fourth lens unit are properly set.

Abstract: An imaging lens SL comprising, in order from an object side: a first group G1 having positive refractive power; an aperture stop S; a second group G2 having positive refractive power; and a third group G3 having negative refractive power; upon focusing from infinity to a close object, the first group and the second group moving independently along an optical axis toward the object side, the first group including, in order from the object side, a front group having negative refractive power, and a rear group having positive refractive power, and the front group consisting of, in order from the object side, a positive lens and a negative lens, thereby providing an imaging lens capable of obtaining excellent optical performance upon focusing from infinity to a close object, with downsizing the optical system with a simple lens construction, an optical apparatus and a method for manufacturing the imaging lens.

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 includes a first lens unit including one of an SLM or a VFL, a second lens unit being optically coupled between the first lens unit and a focal plane and including one of an SLM or a VFL, and a control unit controlling focal lengths of the first and second lens units. A distance between the first lens unit and the second lens unit and a distance between the second lens unit and the focal plane are invariable. The control unit changes a magnification ratio of the zoom lens by changing the focal lengths of the first and second lens units.

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 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 positive first lens unit, a negative second lens unit, a positive third lens unit, and a positive fourth lens unit. During zooming from a wide-angle end to a telephoto end, the first lens unit moves with a locus convex toward the image side, and the third lens unit moves toward the object side. The first lens unit includes, in order from the object side to the image side, a negative first lens, a positive second lens, and a positive third lens. A distance (d12) between the first lens and the second lens, a focal length (fw) of the entire zoom lens at the wide-angle end, and a refractive index (Np) of a positive lens having the lowest refractive index among the refractive indices of materials of all positive lenses included in the first lens unit are appropriately set based on predetermined mathematical conditions.

Abstract: An imaging device, comprising an interchangeable lens having a photographing optical system whose focal length can be varied, comprises a zoom position detection section for detecting a zoom position in accordance with focal length of the imaging optical system, and a lens control section for controlling movement of a focus lens contained in the imaging optical system, wherein the lens control section corrects position that the focus lens is moved to in accordance with the zoom position before movement of the focus lens and zoom position during movement of the focus lens.

Abstract: An optical system includes, in order from an object side to an image side, a first lens unit of a positive refractive power, an aperture diaphragm, and a second lens unit of a positive refractive power. The first lens unit includes, in order from the object side to the image side, a cemented lens Lp1 made by joining a first lens of a positive refractive power and a second lens of a negative refractive power with each other, and a third lens of a positive refractive power which has a meniscus shape. The predetermined conditions are satisfied.

Abstract: A variable beam expander, including: a first lens having a first focal length that is adjustable by a control circuit; a second lens having a second focal length that is adjustable by the control circuit; wherein the first lens and the second lens are separated by a fixed distance; and wherein the control circuit is configured to adjust the first and second focal lengths such that the sum of the first and second focal lengths is equal to the fixed distance.

Abstract: A zoom lens for projection substantially consists of a first lens-group having negative refractive power, and a second lens-group through a fifth lens-group having positive refractive power, arranged in this order from a magnification side. The zoom lens is configured to be telecentric on a reduction side. The first lens-group and the fifth lens-group are fixed while the second lens-group through the fourth lens-group move during magnification change. The fourth lens-group includes at least three positive lenses, and a most-magnification-side lens in the fourth lens-group has a convex surface facing the magnification side. Further, when a focal length of an entire system at a wide angle end is fw, and a focal length of the fourth lens-group is f4, and a full angle of view at a wide angle end is 2?, conditional formulas (1) and (7) are satisfied: 7.5<f4/fw<14.5??(1); and 70°?2???(7).

Abstract: A zoom lens includes a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power, and a fourth lens unit having positive refractive power. During zooming from a wide-angle end to a telephoto end, each lens unit moves so that a distance between the first lens unit and the second lens unit increases, and a distance between the second lens unit and the third lens unit decreases. Each of the first lens unit, the second lens unit, and the third lens unit consists of a single positive lens and a single negative lens, and the fourth lens unit consists of a single positive lens. Focal lengths of the entire zoom lens at the wide-angle end and the telephoto end and focal lengths of the first lens unit and the second lens unit are appropriately set.