Abstract: A zoom lens system according to the present invention, from an object side, comprises a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power. In zooming, the first to the fourth units all move along the optical axis. The third lens unit is composed of three or more lens elements. The condition (6): nd8?1.5 and vd8?75 and the condition (7): (nd9?1)+(nd10?1)?1.55 are satisfied (where, 16<fT/fW, ?>35, and in the third lens unit: nd8, nd9, nd10 are refractive indices to the d-line of the lens elements located on the most object side and at the second and the third positions from the object side; vd8 is an Abbe number to the d-line of the lens element on the most object side; ? is a half view angle at a wide-angle limit; fT is a focal length of the entire system at a telephoto limit; and fW is a focal length of the entire system at a wide-angle limit).

Abstract: A zoom lens includes, in order from an object side to an image side, a front lens group including a first lens unit having positive refractive power and a second lens unit having refractive power, and a rear lens group including a plurality of lens units. The second lens unit includes a reflective member configured to bend an optical path. At least the first lens unit and at least two lens units of the rear lens group move during zooming. The second lens unit does not move for zooming. A reflection unit including the reflective member moves perpendicularly to an optical axis of the front lens group during retraction. At least part of the front lens group is retractable into a space caused by movement of the reflection unit. A focal length f2 of the second lens unit and a focal length ft of the entire zoom lens at a telephoto end are appropriately set.

Abstract: An image pickup apparatus satisfying certain conditional expressions comprises a zoom lens and an image pickup element. The zoom lens consists of, in order from the object side, a first lens unit having a positive refractive power in which a reflecting surface that deflects the optical path is provided, a second lens unit, comprising a plurality of negative lenses, having a negative refractive power, a rear lens unit, comprising a third lens unit and a fourth lens unit, having a positive refractive power, and an aperture stop between the second and fourth lens units. During zooming from the wide angle end to the telephoto end, the first lens unit is fixed, the second lens unit moves in such a way as to be located closer to the image side at the telephoto end than at the wide angle end, and the distances between the lens units change.

Abstract: Provided is a zoom lens for imaging an object on an imaging surface. The zoom lens includes, in the order from an object side to an image side thereof, a first lens group with positive refraction power, a second lens group with negative refraction power, a third lens group with positive refraction power, and a fourth lens group with positive refraction power. The first lens group includes a first surface. The zoom lens satisfies the formula: 0.15<|L3|/Lt<0.25, where L3 is a distance of the movement of the third lens group along an optical axis of the zoom lens when the zoom lens is switched between a wide-angle state and a telephoto state, and Lt is a distance from the first surface to the imaging surface.

Abstract: A zoom lens includes N lens units, in which a lens unit having a positive refractive power is disposed closest to an object side. Each lens unit is moved to effect zooming. An (N?1)th lens unit and an N-th lens unit, counted from the object side, have positive refractive powers. The (N?1)th lens unit includes a first lens subunit having a positive refractive power and a second lens subunit having a negative refractive power in order from the object side to an image side. The second lens subunit is moved to have a component in a direction perpendicular to an optical axis to move an image position. A focal length fN of the N-th lens unit, a back focus bkt at the telephoto end, and an amount of movement mN of the N-th lens unit during zooming from a wide-angle end to a telephoto end are appropriately set.

Abstract: A zoom lens ZL installed in an electronic still camera 1 includes a first lens group G1 having positive refractive power disposed to the most object side, a second lens group G2 disposed to an image side of the first lens group G1, and a Gn lens group having positive refractive power disposed to the most image side. Upon zooming, the first lens group G1 and the Gn lens group are fixed. Upon focusing, at least one lens group disposed between the second lens group G2 and the Gn lens group are moved as a focusing lens group Gf. With this lens configuration, it becomes possible to provide a zoom lens having an optical property capable of coping with a vibration reduction, and an optical apparatus equipped therewith, and a method for manufacturing the zoom lens.

Abstract: Providing a zoom lens system having a vibration reduction function capable of performing quick focusing with excellent optical performance even upon vibration reduction. The system including, in order from an object, 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, and a fourth lens group G4 having positive refractive power. 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 varies, and a distance between the second lens group G2 and the third lens group G3 varies. The third lens group G3 carries out focusing from an infinity object to a close object. At least a portion of the fourth lens group G4 moves in a direction perpendicular to the optical axis.

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, the second lens group including, in order from the object side, a first negative lens and a cemented lens including a second negative lens having a convex shape on the object side and a positive lens, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and an aperture stop arranged between the second lens group and the third lens group, wherein when changing a magnification from a short focal end to a telephoto end, an interval between the first lens group and the second lens group is increased, an interval between the second lens group and the third lens group is decreased, an interval between the third lens group and the fourth lens group is increased, and the first lens group and the third lens group are moved to be located closer to the object side at the long focal end than the short fo

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, an aperture stop, a third lens unit having a positive refractive power, and a rear group including at least one lens unit. During zooming from a wide angle end to a telephoto end, the first and third lens units move to the object side, the second lens unit moves to the image side, and the aperture stop moves to the object side along a convex path. Radii of curvature of object- and image-side lens surfaces of a lens closest to the object side in the second lens unit, focal lengths of the entire zoom lens at the wide angle end and the telephoto end, and focal lengths of the first and second lens units are set properly.

Abstract: A variable power zoom lens of four groups of lens pieces respectively exerting positive, negative, positive, and positive refractivities varies the power from the wide-angle end to the telephoto end as a result of the 1st and 2nd lens groups being separated more, the 2nd and 3rd lens groups, and the 3rd and 4th lens groups, coming closer to each other. The 3rd lens group has a leading set of lens pieces closer to the object side having a positive refractivity as a whole and the trailing set of lens pieces have negative refractivity as a whole, and the trailing set alone are moved to be orthogonal to the optical axis to compensate for defocus in the imaging plane. The 2nd lens group is displaced closer to objects for focusing.

Abstract: A variable focal length lens system including: a first lens group having positive power; a second lens group having negative power; a third lens group having positive power; and a fourth lens group having positive power sequentially arranged from a side where an object is present. An aperture stop is disposed between the second and third lens groups. The first to fourth lens groups are so moved that the distance between the first and second lens groups increases, the distance between the second and third lens groups decreases, and the distance between the third and fourth lens groups decreases when a lens position setting is changed from a wide angle end state to a telescopic end state. The third lens group includes a negative lens and a positive lens disposed on the image side thereof. The variable focal length lens system satisfies the following conditional expression. 0.35<f3/|f3a|<0.

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

Abstract: A zoom lens system comprising in order from an object side to an image side: a first lens unit having a positive refracting power; a second lens unit having a negative refracting power; a third lens unit having a positive refracting power; and a fourth lens unit having a positive refracting power, wherein at the time of zooming from a wide angle end to a telephoto end, each of distances between the first lens unit and the second lens unit, between the second lens unit and the third lens unit, and between the third lens unit and the fourth lens unit is changed, and the first lens unit is moved, the first lens unit comprises a lens component having positive refracting power, a total number of lens components included in the first lens unit is one, and the third lens unit comprises five lens elements.

Abstract: Wide-angle large-aperture zoom lens provides a field angle greater than 75° at the wide-angle end and a variable magnification power of 2.5 or greater, and can downsize a compensation mechanism for image blur due to hand tremors. The zoom lens includes a first lens group LG1 of positive refractive power, a second lens group LG2 of negative refractive power, a third lens group LG3 of positive refractive power, and a fourth lens group LG4 of positive refractive power, all arranged in sequence from the closest to an object to the closest to an imaging plane, and permits magnification power to vary by varying clearances between adjacent ones of the first lens group LG1 to the fourth lens group LG4. Part of the lens pieces in the third lens group is moved orthogonally to the optical axis to compensate for image blur due to hand tremors.

Abstract: Disclosed is a zoom lens having 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; and a fourth lens group G4 having positive refractive power. 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 is changed, a distance between the second lens group G2 and the third lens group G3 is changed, and the fourth lens group G4 is moved toward the object first, then moved toward an image. The third lens group G3 has a first positive lens L31, a negative lens L32 and a second positive lens L33, and the fourth lens group G4 has two lenses: L41 and L42.

Abstract: The zoom lens Z1 having, in order from an object, 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, and a fourth lens group G4 having positive refractive power, wherein the conditional expression 2.70<TLt/(fw×ft)1/2<3.70 as well as the conditional expression 0.05<D1/ft<0.29 are, where TLt denotes a total length of the zoom lens ZL in a telephoto end state, fw denotes a focal length of the zoom lens ZL in a wide-angle end state, ft denotes a focal length of the zoom lens ZL in a telephoto end state, and D1 denotes a thickness of the first lens group G1 on the optical axis.

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

Abstract: A lens system and an image capturing device having the same include 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 being exchangeable with the third lens group.

Abstract: A zoom lens and an image pickup device. The 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, and a fourth lens group having a positive refractive power, which are arranged in order from an object side to an image side, wherein, when the zoom lens is zoomed from a wide angle position to a telephoto position, all of the first lens group, the second lens group, the third lens group, and the fourth lens group move relative to one another so that a distance between the first lens group and the second lens group increases, a distance between the second lens group and the third lens group reduces, and a distance between the third lens group and the fourth lens group increases.

Abstract: A zoom lens includes, in order from the object side to the image side, a positive refractive first lens unit, a negative refractive second lens unit, a positive refractive third lens unit, and a rear group including one or more lens units. The first lens unit consists of a negative lens and a positive lens. The first to third lens units and the lens units constituting the rear group move at a time of zooming. The first and third lens units move relative to the image plane in such a way that their respective positions at the telephoto end are displaced toward the object side from their respective positions at the wide angle end. The focal lengths f1, f2 of the first and second lens units and the focal lengths fw, ft of the whole system at the wide angle end and at the telephoto end are arranged appropriately.

Abstract: A zoom lens includes a first lens group, a second lens group, an aperture, a third lens group, a fourth lens group, a fifth lens group, and an image surface in order along an optical axis from an object side to an image side. The first lens group has positive refractive power, and includes three lenses. The second lens group has negative refractive power, and includes fourth lenses. The third lens group has positive refractive power, and includes two lenses. The fourth lens group has positive refractive power, and includes five lenses. The fifth lens group has positive refractive power, and includes two lenses. Therefore, the zoom lens has a small size and high zoom ratio.

Abstract: Provided is an optical system (PS) which is used in a wavelength range including a near ultraviolet light range having a wavelength longer than approximately 350 nm and a visible light range. The optical system includes at least two first positive lenses which satisfies a predetermined conditional expression concerning anomalous dispersion characteristic and a rate of change of the refractive index with respect to temperature, and is disposed closer to a contraction side than an aperture stop (ST), and at least one second positive lens which satisfies a predetermined conditional expression concerning anomalous dispersion characteristic and a rate of change of the refractive index with respect to temperature.

Abstract: A zoom lens includes, in order from the object side to the image side: a first lens group that has a positive refractive power; a second lens group that has a negative refractive power; a third lens group that has a positive refractive power; and a fourth lens group that has a positive refractive power

Abstract: A zoom lens includes, a first lens unit of a positive refractive power, a second lens unit of a negative refractive power, a reflective element, and a rear lens group including two or more lens units and an aperture stop, in which the first lens unit, the second lens unit, and two or more lens units of the rear lens group are moved while the reflective element is stationary during zooming, wherein movement amounts M1 and M2 of the first and second lens units during zooming, a movement amount Ms of the aperture stop, and focal lengths fw and ft of the entire zoom lens at the wide-angle end and the telephoto end, respectively, lateral magnifications ?2w and ?2t of the second lens unit, a distance LSw from the first lens surface to the aperture stop at the wide-angle end 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; a second lens unit having negative optical power; a third lens unit having positive optical power; and a subsequent lens unit, wherein in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit, the second lens unit, and the third lens unit are moved along an optical axis to perform magnification change, wherein the third lens unit has at least two air spaces, and the conditions: ?4.9<f1/f2<?3.0 and Z=fT/fW>6.5 (f1 and f2: composite focal lengths of the first and second lens units, fT and fW: focal lengths of the entire system at a telephoto limit and a wide-angle limit) are satisfied.

Abstract: A zoom lens and a photographing apparatus having the same. The 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 that are sequentially arranged from an object side to an image plane side. An interval between the lens groups adjacent to each other varies when the zoom lens zooms from a wide angle position to a telephoto position. The zoom lens satisfies the following inequality: 1.8<|?3T/?3W|<2.2??<Formula> where ?3T denotes the magnification of the third lens group at the telephoto position, and ?3W denotes the magnification of the third lens group at the wide angle position.

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. All of the lens units are moved during zooming from a wide-angle end to a telephoto end. An aperture stop is arranged on the image side of the third lens unit. A distance T23 from a lens surface closest to the image side in the second lens unit to a lens surface closest to the object side in the third lens unit when the zoom lens is at the telephoto end, a focal length fT of the entire zoom lens at the telephoto end, and focal lengths f1, f2, and f3 of the first, second, and third lens units, respectively, are set based on predetermined mathematical conditions.

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. The first to fourth lens units move during zooming. The first lens unit includes a cemented lens obtained by cementing negative and positive lenses, the second lens unit includes negative, negative, and positive lenses, the third lens unit includes positive and negative lenses, and the fourth lens unit includes a positive lens. Movement amounts M1 and M3 of the first and third lens units, respectively, during zooming from the wide-angle end to the telephoto end and focal lengths f1 and f3 of the first and third lens units, respectively, are appropriately set based on predetermined mathematical conditions.

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, the first, second, third, and fourth lens groups being arranged in order from an object side, and satisfies conditional expression (1) and conditional expression (2) below, (1) 0.95<|fw12|/fw<1.2 and (2) 140<f1/?t234<150, where, fw12 denotes a synthetic focal length of the first lens group and the second lens group at a wide-angle end, fw denotes a focal length of a whole lens system at the wide-angle end, f1 denotes the focal length of the first lens group, and ?t234 denotes the synthetic magnification of the second lens group, the third lens group, and the fourth lens group at a telephoto end.

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

Abstract: A projection objective of a microlithographic projection exposure apparatus has a high index refractive optical element with an index of refraction greater than 1.6. This element has a volume and a material related optical property which varies over the volume. Variations of this optical property cause an aberration of the objective. In one embodiment at least 4 optical surfaces are provided that are arranged in at least one volume which is optically conjugate with the volume of the refractive optical element. Each optical surface comprises at least one correction means, for example a surface deformation or a birefringent layer with locally varying properties, which at least partially corrects the aberration caused by the variation of the optical property.

Abstract: A high-performance zoom lens system which is compact and has a wide view angle at a wide-angle limit and a high zooming ratio in a balanced manner, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and the conditions: ?2.3<f2/fW<?1.5, ?W?36 and fT/fW>4.

Abstract: A zoom lens system includes in order from an object side to an image side, a first lens unit G1 having a positive refracting power, a second lens unit G2 having a negative refracting power, a third lens unit G3 having a positive refracting power, and a fourth lens unit G4 having a positive refracting power. At the time of zooming from a wide angle end to a telephoto end, distances between the lens units change. The third lens unit includes a first cemented lens component having a concave image-side surface on the image side, and a second cemented lens component having a concave object-side surface on the object side, which is disposed immediately after the image side of the first cemented lens component. The first cemented lens component includes a positive lens, and a negative lens having a concave image-side surface which is disposed on the image side of the positive lens.

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

Abstract: Provided is a zoom lens including, in order from an object side to an image side: a positive first lens unit having two positive lenses and a negative lens; a negative second lens unit having positive and negative lenses; a positive third lens unit; and a rear group including lens unit, wherein: with respect to a wide angle end, at a telephoto end, intervals between the first and second lens units, the second and third lens units, and the third lens unit and the rear group respectively change; and a focal length and an Abbe number of a material of the positive lens of the first lens unit that has a largest Abbe number among positive lenses, a refractive index and an Abbe number of a material of the positive lens of the second lens unit, and a focal length of the first lens unit are set appropriately.

Abstract: The present invention is directed to high magnification compact zoom lenses that are reduced in diameter of groups of lens pieces closer to the imaging plane to provide downsized lightweight zoom lenses of magnification as high as 20 diameters, with an image stabilizer or vibration compensating mechanism being also reduced in dimensions. An exemplary improved high magnification zoom lens has four groups of lens pieces, namely, the first or leading lens group G1 of positive refractivity in the foremost position closer to the subject, the second lens group G2 of negative refractivity, the third lens group G3 of positive refractivity, and the fourth lens group G4 of positive refractivity in the rearmost position closer to the imaging plane, all arranged in this order.

Abstract: A zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group, and a positive fourth lens group, in this order from an object. Upon zooming from the short focal length extremity to the long focal length extremity, the distance between the first and the second lens groups increases, and the distance between the second and the third lens groups decreases. The third lens group includes a positive first sub-lens group and a negative second sub-lens group, in this order from the object. The first sub-lens group comprises a positive lens element provided at the most object-side thereof and a cemented lens provided at the most image-side thereof. The cemented lens includes a positive lens element and a negative lens element, in this order from the object.

Abstract: The present invention is directed to an inner focusing macro lens that has a large aperture ratio as expressed by 2.5 or even smaller in F-number and still remains compact, and that is adapted to compensate for spherical aberration, astigmatism, and comatic aberration during photographing throughout the entire object distance ranging from infinity to proximity for an up to 1:1-magnification image. The inner focusing macro lens has the leading or first lens group of positive refractivity, the second lens group of negative refractivity, the third lens group of positive refractivity, and the trailing lens set succeeding to the third lens group in sequence from a position closest to an object being photographed. During focusing from a point infinitely far to that as proximal as desired, the first lens group is static while the second lens group is moved toward the imaging plane, and the third lens group is moved toward the object.

Abstract: A telephoto zoom lens having four lens groups in a P-N-P-P configuration arranged sequentially from an object side. The first lens group includes a front group which is fixed when focusing and has a positive refractive power, and a rear group which moves when focusing and has a positive refractive power. The entire first lens group, including the front and rear groups, is fixed during zooming, and the second and third lens groups move during zooming. The second lens group compensates for shaking of an image plane caused by hand-shaking, by moving in a direction perpendicular to the optical axis, and satisfies the following condition: 1.2<f1a/f1b<1.8 where f1a and f1b denote the focal length of the front group of the first lens group and the focal length of the rear group of the first lens group, respectively.

Abstract: Example methods and apparatus to perform multi-focal plane image acquisition and compression are disclosed. A disclosed example method includes capturing a first image of a portion of an object at a first focal plane and at a first resolution, computing a contrast metric for the captured first image, comparing the contrast metric to a threshold to determine whether to capture a second image of the portion of the object at the first focal plane and at a second resolution, wherein the second resolution is different from the first resolution, capturing the second image of the portion of the object at the first focal plane and at the second resolution, and storing a first representation of the second image in a file, the file containing a second representation of the portion of the object at a second focal plane, wherein the second representation is at the first resolution.

Abstract: A zoom lens system includes, in the order from the object side to the image side thereof, a first lens group of positive refraction power, a second lens group of negative refraction power, a third lens group of positive refraction power, a fourth lens of positive refraction power, and an imaging plane. The first lens group and the third lens group are immovably mounted. The second lens group and the fourth lens group are movably mounted. The zoom lens system satisfies the formulae: 5<f3/f4<8.2; and 2.1<|f2/fw|<3.2, wherein f2-f4 respectively represent the effective focal lengths of the second, third and fourth lens groups, fw represents the shortest effective focal length of the zoom lens system.

Abstract: An embodiment of this invention provides a zoom lens that includes, in order from an object side to an image-forming side, a first lens group having positive refraction power; a second lens group having negative refraction power; a third lens group having positive refraction power; and a fourth lens group having positive refraction power; wherein the second lens group and the fourth lens group move along an optical axis for zooming between a wide-angle end and a telephoto end.

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: A zoom lens includes, in order from an object side: a first lens unit having a positive refractive power which does not move for varying magnification; a second lens unit having a negative refractive power which moves for varying magnification; a third lens unit having a positive refractive power which moves for varying magnification; and a fourth lens unit having a positive refractive power which does not move for varying magnification, in which: the first lens unit includes a first sub lens unit which does not move for focusing and a second sub lens unit having a positive refractive power which moves for focusing; the first sub lens unit includes three lenses having negative, positive, and positive refractive powers; and each of the elements is appropriately set.

Abstract: A 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 side. Upon zooming from the short to long focal length extremities, the distance between the first and second lens groups increases, the distance between the second and third lens groups decreases, and the distance between the third and fourth lens groups changes. The second lens group includes a negative lens element having a concave surface on the image side, a negative lens element having a concave surface on the image side, and a plastic positive lens element having an aspherical surface on at least one side and having a convex surface on the object side, in that order from the object side.

Abstract: A zoom lens system, in order from an object side to an image side, comprising a first lens unit of positive power, a second lens unit of negative power, a third lens unit of positive power, and a fourth lens unit of positive power, wherein the first lens unit is composed of three or fewer lens elements, wherein the second lens unit is composed of three lens elements, wherein in zooming, the first to the fourth lens units are moved individually along an optical axis such that air spaces should vary, so that variable magnification is achieved, and wherein the conditions are satisfied: tan 2?W×m2W??1.78, tan 2?W×|fG2|/fG1?1.25, ?W?37 and fT/fW?10 (m2W is a lateral magnification of the second lens unit at a wide-angle limit, fG1 and fG2 are composite focal lengths of the first and the second lens units, ?W is a half view angle at a wide-angle limit, and fT and fW are focal lengths of the entire system respectively at a telephoto limit and at a wide-angle limit), an imaging device and a camera are provided.

Abstract: A zoom optical system in which: a positive first lens group, a negative second lens group, a positive third lens group, and a positive fourth lens group are arranged in that order from the object side and magnification is changed by properly changing distances between these lens groups; the first lens group consists of only one lens element and the most object-side surface of the first lens group has a convex shape which faces toward the object side; the second lens group includes, in order from the object side, a negative single lens, a negative cemented lens, and a positive single lens; and the following condition (1) or (2) is satisfied: 0.2??Dw-w10/Lt?0.

Abstract: The present invention provides a zoom lens ZL comprising 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, and a fourth lens group G4 having positive refractive power, the first lens group G1 including a negative meniscus lens L11 and a positive meniscus lens L12, the second lens group G2 including a negative meniscus lens L21, a biconcave negative lens L22 and a positive meniscus lens L23, and the fourth lens group G4 including one positive lens L41, and the refractive indexes of at least three lenses in the zoom lens ZL being greater than 1.9.

Abstract: A zoom lens comprising, 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, and a fourth lens unit of a positive refractive power. In zooming, the first lens unit is configured fixed and the second, third, and fourth lens units are configured movable. The following conditions are satisfied where f3st is a movement amount of the third lens unit associated with zooming from a wide angle end to a telephoto end, f3 is a focal length of the third lens unit, ?2w is a lateral magnification of the second lens unit at the wide angle end, and z is a zoom ratio, 0.010<(|f3st|/f3)/z<0.045, and ?0.33<?2w<?0.20.

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 negative refractive power. The first to fourth lens units are arranged in order from the object side to the image side. All of the lens units are moved during zooming from the wide-angle end to the telephoto end. In the zoom lens, a number of lenses in each of the lens units, imaging magnifications on the telephoto end and the wide-angle end of the second lens unit and the third lens unit, a sum of thicknesses on the optical axis of the first lens unit and the second lens unit, and focal lengths of the entire zoom lens at a wide-angle end and at a telephoto end are appropriately set.