Abstract: The lens apparatus includes an aperture stop (SP) forming an aperture, a first lens (A or B) disposed on a first side further than the aperture stop, the first side being one of an object side and an image side, and a second lens (B or A) disposed on a second side further than the aperture stop, the second side being the other of the object side and the image side. In zooming or focusing, the aperture stop is moved independently of the first and second lenses. The first lens and the aperture stop are brought into a first state where an aperture stop side lens surface of the first lens is located away from the aperture stop on the first side and a second state where at least part of the aperture stop side lens surface (RA or RB) of the first lens protrudes through the aperture to the second side further than the aperture stop.

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

Abstract: An optical system includes, in order from an object side, a first lens unit having a negative refractive power and a second lens unit having a positive refractive power. The optical system satisfies: 1.70?Yt/Yw?2.5, Y=2×f×sin(?/2))(85°???90°), and 3.45?bfw/|f1|?7, where fw is the shortest focal length, ft is the longest focal length, f is an arbitrary focal length that satisfies fw?f?ft, ? is an angle between the optical axis and a principal ray of an off-axis light flux incident upon a lens surface closest to the object, Y is a formed image height of a ray incident at the angle ?, Yw is the largest image height at the shortest focal length, Yt is the largest image height at the longest focal length, f1 is a focal length of the first lens unit, and bfw is a back focus at the shortest focal length.

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

Abstract: The imaging lens includes, in order from an object side, a first lens group having positive refractive power; and a second lens group having the positive refractive power, the first lens group being fixed with respect to an image plane, the second lens group being moved toward the object side to adjust a focus on a close object, and a given conditional expression being satisfied, thereby disclosing a downsized imaging lens having a wide angle of view, capable of preferably correcting various aberrations upon focusing on a close object from an infinitely distant object and having high optical performance over an entire picture, an optical apparatus including the imaging lens and an imaging lens manufacturing method.

Abstract: A zoom lens, including: a front lens group; an aperture stop; and a rear lens group, in which the rear lens group includes: a front lens unit and a rear lens unit, a maximum air interval of the rear lens group being interposed between the front lens unit and the rear lens unit, in which the rear lens unit includes: a first lens which is located on the most object side; a second lens which is located on the most image side, and the following conditional expressions are satisfied: ?6.0?fs1/frr??1.0; and ?9.0?fs3/frr??2.0, where frr indicates a focal length of the rear lens unit, and fs1 and fs3 indicate a focal length of the first lens and a focal length of the second lens, respectively.

Abstract: A variable power optical system is provided and includes: in order from the object side, a first lens group having a negative refractive power and including a negative lens group and a positive lens group; a stop; and a second lens group having a positive refractive power and including a sub-lens group on the most object side, the sub-lens group including a first lens having a positive refractive power having at least one aspherical surface, a second lens having a positive refractive power, and a third lens having a positive refractive power. The second lens group is moved to the object side along an optical axis thereof to perform a variable power operation from a wide angle end to a telephoto end of the variable power optical system, and the first lens group is moved to make a correction of an image plane position in accordance with the variable power operation.

Abstract: An optical system includes a front lens group, a stop, and a rear lens group arranged successively in order from the object side toward the image side. The front lens group includes a solid material element having a refractive action. The rear lens group includes a diffractive optical element. The solid material element is formed on at least one transmissive surface of a refractive optical element. An Abbe number of a solid material of the solid material element with respect to the d line, a partial dispersion ratio of the solid material with respect to the g line and the F line, respective thicknesses of the solid material element and the refractive optical element when measured on the optical axis, and respective focal lengths of the diffractive optical portion of the diffractive optical element and the solid material element in air satisfy predetermined conditional expressions.

Abstract: A compact wide-angle zoom lens and an image pickup device having the same. The zoom lens includes a first lens group having a negative refractive power and a second lens group having a positive refractive power in an order from an object side to an image side, performs zooming by varying a distance between the first and second lens groups, and performs focusing by using a first lens closest to the object side in the second lens group.

Abstract: In a zoom lens ZL1 having a plurality of lens groups G1 to G2 which are disposed in order from an object, where a refractive index average value of the lens components which constitute the zoom lens ZL1 is defined as ndav and a refractive index average value of the lens components which constitute the first lens group G1 which is disposed to closest to the object among the plurality of lens groups G1 to G2 is defined as ndGlav, the zoom lens ZL1 is constituted to satisfy the conditional expression ndav?1.80 and to satisfy the conditional expression ndGlav?1.85.

Abstract: Provided is a small-sized five-element image pickup lens which ensures a sufficient lens speed of about F2 and exhibits various aberrations being excellently corrected. The image pickup lens is composed of, in order from the object side, a first lens with a positive refractive power, including a convex surface facing the object side; a second lens with a negative refractive power, including a concave surface facing the image side; a third lens with a positive or negative refractive power; a fourth lens with a positive refractive power, including a convex surface facing the image side; and a fifth lens with a negative refractive power, including a concave surface facing the image side. The image-side surface of the fifth lens has an aspheric shape, and includes an inflection point at a position excluding an intersection point with the optical axis.

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

Abstract: A lens system includes, in order from an object: a first lens group having negative refractive power; and a second lens group having positive refractive power, the first lens group including, in order from the object, a lens having a negative refractive power, a plastic aspherical lens, and a lens having a positive refractive power, and the following conditional expression |fp/f1|>4.0 being satisfied, where fp denotes a focal length of the plastic aspherical lens, and f1 denotes a focal length of the first lens group.

Abstract: An imaging optics capable of compensating for chromatic aberration is provided with a light shielding means in a surface peripheral area of a certain lens element in a lens system so as to block a light flux of a specified wavelength range, thereby eliminating chromatic aberration in halo of the light flux of the specified wavelength range when it passes the periphery of the lens system. Thus, the invention provides the imaging optics that, without an increase in the number of pieces of lens elements and without a use of an expensive specified low-dispersion glass material, in contrast with the prior art imaging optics of the same optical performances, well compensates for chromatic aberration, especially, in halo.

Abstract: A video projection device has one of a plurality of types of projection lenses replaceably loaded and projects a video on a screen at a fixed position. The video projection device includes: a converter lens which is composed of a plurality of lenses, which is afocal as a whole, and which is detachably provided in front of the projection lens to convert projection magnification; and a gap adjustment mechanism changing a predetermined gap in the converter lens to a setting in accordance with at least one of a projection distance to the screen and the type of the projection lens loaded.

Abstract: A zoom lens includes sequentially from an object side a first lens group having a negative refractive power; a diaphragm; and a second lens group having a positive refractive power. Zoom from a wide angle edge to a telephoto edge is performed by displacement of the second lens group along an optical axis, toward the object side. Correction of imaging plane variation accompanying zoom, is performed by displacement of the first lens group along the optical axis. The second lens group includes a positive first lens disposed farthest on the object side and having at least one aspheric surface, and a cemented lens that includes a negative lens, a positive lens, and a negative lens. Furthermore, a first condition ?d2p>75 is satisfied, ?d2p being the Abbe number for a d-line in the positive lens included in the cemented lens of the second lens group.

Abstract: A zoom lens includes sequentially from an object side a first lens group having a negative refractive power; a diaphragm; and a second lens group having a positive refractive power. Zoom from a wide angle edge to a telephoto edge is performed by displacement of the second lens group along an optical axis, toward the object side. Correction of imaging plane variation accompanying the zoom, is performed by displacement of the first lens group along the optical axis. The second lens group includes sequentially from the object side, a positive first lens having at least on aspheric surface and a positive second lens. Furthermore, a first condition ?d21>63 and a second condition ?d22>70 are satisfied, ?d21 being the Abbe number for a d-line in the first lens of the second lens group and ?d22 being the Abbe number for a d-line in the second lens of the second lens group.

Abstract: An zoom lens includes a front unit having positive refractive power, an aperture stop, and a rear unit. The front unit has a positive lens Gp1 and the rear unit has a negative lens Gn1. When an Abbe number of a material of the positive lens Gp1, and a partial dispersion ratio of the material thereof for a g-line and an F-line is defined as ?dp1 and ?gFp1 respectively, and a refractive index and an Abbe number of a material of the negative lens Gn1 for a d-line, and a partial dispersion ratio of the material thereof for the g-line and the F-line is defined as Ndn1 ?dn1 and ?gFn1 respectively, satisfying the following conditions: 75<?dp1<99, 0.020<?gFp1?0.6438+0.001682×?dp1<0.100, 1.75<Ndn1<2.10, and 0.020<?gFn1?0.6438+0.001682×?dn1<0.100.

Abstract: Disclosed are a projection lens that has a simple inner focus structure, an appropriate back focal length, telecentricity, a high optical performance, and a small size and can effectively correct, particularly, lateral chromatic aberration, and a projection display device. A projection lens includes a first lens group having a negative refractive power and a second lens group having a positive refractive power arranged in this order from a magnification side. A fifth lens arranged closest to a reduction side in the first lens group is moved along an optical axis to adjust focus, and at least two lenses are made of a material with anomalous dispersion capable of reducing chromatic aberration in a wide visible range.

Abstract: A zoom lens ZL installed in an electronic still camera 1 includes, in order from an object side, a first lens group G1 having negative refractive power, and a second lens group G2 having positive refractive power. A distance between the first lens group G1 and the second lens group G2 varies upon zooming from a wide-angle end state to a telephoto end state. The second lens group G2 has a front lens group G2F and a rear lens group G2R, and the front lens group G2F is moved along the optical axis upon focusing on a close object, thereby providing a compact zoom lens having excellent optical performance, an optical apparatus equipped with the zoom lens, and a method for manufacturing the zoom lens.

Abstract: A miniature auto-focusing lens device includes a first casing, a second casing coupled to the first casing, a movable lens set disposed in the first casing, an electromagnetic driving module provided in the first casing and configured to drive the movable lens set to perform focusing and displacement, and a fixed lens set coupled to the second casing and corresponding in position to the movable lens set. The movable lens set and the fixed lens set together form an optical system of the miniature auto-focusing lens device to perform optical focusing and imaging. The fixed lens set includes a lens that outstrips any one of the lenses of the movable lens set in size.

Abstract: A zoom lens including a first lens group and a second lens group arranged in sequence from a magnified side toward a reduced side is provided. The first lens group has a negative refractive power and includes a first lens, a second lens, a third lens, and a fourth lens arranged in sequence from the magnified side toward the reduced side, of which the refractive powers are respectively positive, negative, negative, and positive. The second lens group has a positive refractive power and includes a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, and an eleventh lens arranged in sequence from the magnified side toward the reduced side, of which the refractive powers are respectively positive, negative, positive, negative, positive, negative, and positive. The eighth lens, the ninth lens, and the tenth lens together form a triple cemented lens.

Abstract: The invention relates to an eyepiece optical system that, albeit being of small size, works in favor of gaining an angle of field and optical performance, and an electronic view finder incorporating such an eyepiece optical system. Specifically, the invention is characterized by comprising, in order from an object side to an exit side thereof, a first lens group that is a single lens that has positive refracting power and is in a meniscus configuration concave on its object side, a second lens group that is a single lens that has negative refracting power and is in a meniscus configuration concave on its object side, and a third lens group that is a single lens that has positive refracting power, wherein an object-side concave lens surface in the first lens group is an aspheric surface, an object-side concave lens surface in the second lens group is an aspheric surface, and an exit-side lens surface in the third lens group is an aspheric surface.

Abstract: A zoom lens includes a first lens group and a second lens group disposed between the first lens group and an image side. The first lens group has three lenses. Refractive powers of the three lenses arranged from an object side to the image side are respectively negative, negative, and positive. The second lens group has five lenses. Refractive powers of the five lenses arranged from the object side to the image side are respectively positive, negative, positive, negative, and positive. Effective focal lengths (EFL) of the first and the second groups are respectively f1 and f2. The EFL of the zoom lens is fw when the zoom lens is switched to a wide end. The zoom lens satisfies ?2.8<f1/fw<?2.5 and 0.75<|f1/f2|<0.9.

Abstract: An optical element unit is provided comprising an optical element group for projecting light along an optical axis of the optical element group and a housing having an inner housing part partly defining a first space and a light passageway between the inner housing part and a second space. The inner housing part receives the optical element group. The optical element group comprises an ultimate optical element located in the region of the light passageway. A load-relieving device is provided adjacent to the ultimate optical element, the load relieving device partly defining the first space and the second space and at least partly relieving the ultimate optical element from loads resulting from pressure differences between the first space.

Abstract: A relay zoom system includes, in order from an object side, a first lens group having a positive refractive power and a second lens group having a positive refractive power. Furthermore, in the relay zoom system, the first lens group and the second lens group are each made up of at least two positive lenses and one negative lens. The first lens group and the second lens group in the relay zoom system are configured so as to move along an optical axis when magnification is varied from a lower magnification edge state to a higher magnification edge state.

Abstract: An image forming optical system according to the present invention is characterized in that, in an image forming optical system having a positive lens group, a negative lens group, and an aperture stop, the positive lens group is disposed at an object side of the aperture stop, the positive lens group has a cemented lens which is formed by cementing a plurality of lenses, in a rectangular coordinate system in which a horizontal axis is let to be Nd and a vertical axis is let to be ?d, when a straight line indicated by Nd=?×?d+? (where, ?=?0.017) is set, Nd and ?d of at least one lens forming the cemented lens is included in both of areas namely, an area which is determined by a line when a lower limit value is in a range of a following conditional expression (1a), and a line when an upper limit value is in a range of the following conditional expression (1a), and of an area determined by following conditional expressions (2a) and (3a). 1.45<?<2.15??(1a) 1.30<Nd<2.

Abstract: The variable-power optical system is provided and includes a first lens group having a negative refractive power, a stop, and a second lens group having a positive refractive power, in order from an object side. The first lens group includes a first sub lens group having three negative meniscus lenses and a second sub lens group having a biconcave lens and a positive lens, in order from the object side. The second lens group includes a first positive lens arranged closest to the object side and having at least one aspheric surface and a second positive lens arranged immediately after the image side of the first positive lens. When the absolute value of the focal length of the first lens group is |f1| and the focal length of the entire system at a wide angle end is fw, the Conditional expression: 1.9<|f1|/fw<3.6 is satisfied.

Abstract: Provided is a zoom lens system including: in order from an object side to an image side, a first lens unit having a positive refractive power; an aperture stop; and a second lens unit, in which the first lens unit includes a first-a lens unit having a positive refractive power and a first-b lens unit having a negative refractive power which moves along an optical axis in focusing, the first-b lens unit includes at least one negative lens and at least one positive lens, and the following conditional expression is satisfied: 0.020<?gF1?0.6438+0.001682×vd1<0.100, where ?gF1 denotes a partial dispersion ratio of a material of the positive lens, and vd1 denotes Abbe number of the positive lens.

Abstract: The invention relates to an electronic image pickup system whose depth dimension is extremely reduced, taking advantage of an optical system type that can overcome conditions imposed on the movement, of a zooming movable lens group while high specifications and performance are kept. The electronic image pickup system comprises an optical path-bending zoom optical system comprising, in order from its object side, a 1-1st lens group G1-1 comprising a negative lens group and a reflecting optical element P for bending an optical path, a 1-2nd lens group G1-2 comprising one positive lens and a second lens group G2 having positive refracting power. For zooming from the wide-angle end to the telephoto end, the second lens group G2 moves only toward the object side. The electronic image pickup system also comprises an electronic image pickup device I located on the image side of the zoom optical system.

Abstract: An object of the invention is to provide a projection lens capable of sufficiently correcting lateral chromatic aberration at both of the wide-angle end and the telephoto end, with an increased zoom ratio, a less number of lens elements, and less variation in telecentricity.

Abstract: A variable power optical system is provided and includes: in order from the object side, a first lens group having a negative refractive power and including a negative lens group and a positive lens group; a stop; and a second lens group having a positive refractive power and includes a sub-lens group having a positive refractive power as a whole and arranged on the most object side, the sub-lens group including a first lens having a positive refractive power having at least one aspherical surface, a second lens having a negative refractive power, and a third lens having a positive refractive power. The second lens group is moved to the object side along an optical axis to perform a variable power operation from the wide angle end to the telephoto end with moving the first lens group to make a correction of an image plane position.

Abstract: An optical imaging system includes a first lens group having a positive or negative optical power, an aperture diaphragm, and a second lens group having a positive optical power arranged in order from an object side. The first lens group includes a first front lens group having at least two negative lenses and a first rear lens group having at least one positive lens with an airspace in-between the first front and rear lens groups. The second lens group includes a second front lens group having first positive and negative lenses, second negative and positive lenses arranged in order from the object side, and a second rear lens group including at least one aspherical lens. When focusing on an object in a close range from infinity, the second lens group moves to the object side while an interval between the second front and rear lens groups are shortened.

Abstract: Disclosed is a zoom lens system in which a first lens unit having negative optical power and a second lens unit having positive optical power are arranged in the stated order from an object side to an image side, and in which an interval between the first lens unit and the second lens unit changes in zooming. In such a zoom lens system, the first lens unit includes a first lens component having negative optical power, a second lens component joined to a lens surface of the first lens component, and a third lens component having positive optical power so as to provide the zoom lens system having excellent optical performance by appropriately setting a material forming the first lens component.

Abstract: This invention provides an imaging lens system including, in order from an object side to an image side: a first lens group with negative refractive power comprising a single first lens element with negative refractive power; a second lens group with positive refractive power comprising, in order from the object side to the image side: a second lens element with positive refractive power; a third lens element with negative refractive power; an aperture stop; and a fourth lens element with negative refractive power; and a third lens group with positive refractive power comprising a single fifth lens element with positive refractive power; wherein by moving the first lens group and the second lens group along the optical axis while keeping the third lens group stationary, the zooming operation is performed such that the system switches between a wide-angle mode and a telephoto mode.

Abstract: The invention relates to an optical system that is capable of providing a zoom lens having improved image-formation capability with a reduced number of lenses, and fabricating a slim yet high-performance digital or video camera. The optical system comprises a cemented lens having a cementing surface on its optical axis. Air contact surfaces on the light ray entrance and exit sides of the cemented lens G2 are aspheric, and at least one cementing surface in the cemented lens G2 satisfies condition (1). 6.4<|(r/R)|??(1) Here r is the axial radius of curvature of the cementing surface, and R is the maximum diameter of the cementing surface.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit having a negative refractive power and a second lens unit having a positive refractive power. In the zoom lens, an interval between the first and second lens units becomes smaller at a telephoto end than at a wide-angle end during zooming. The first lens unit includes, in order from the object side to the image side, a first lens having a negative refractive power, a second lens having a negative refractive power, which is made of a plastic and has an aspheric lens surface, and a third lens unit having a positive refractive power. In the zoom lens, a refractive index and an Abbe number of the plastic (Nd, ?d), a focal length of the second lens (fn), and a focal length of the first lens unit (f1) are appropriately set.

Abstract: A high performance zoom lens system suitable for use with a camera is disclosed. The zoom lens systems employs liquid optics and a movable lens group to provide optical performance over the zoom focal length range at focus distances from close to infinity. The system also provides compensation for undesirable thermally induced effects by adjustments of the zoom group and the variably shaped optical surface in the liquid lens cell.

Abstract: In an image forming optical system having a positive lens group, a negative lens group, and an aperture stop, the positive lens group being disposed at an image-plane side of the aperture stop and having a cemented lens, and when a straight line indicated by Nd=?×?d+? (where, ?=?0.017) is set, Nd and ?d of at least one lens forming the cemented lens are included in both an area which is determined by a line when a lower limit value is in a range of a following conditional expression (1), and a line when an upper limit value is in a range of the following conditional expression (1), and in an area determined by following conditional expressions (2) and (3) 1.45<?<2.15??(1) 1.30<Nd<2.20??(2) 3<?d<25??(3) Here, Nd denotes a refractive index, and ?d denotes an Abbe's number.

Abstract: A zoom lens comprises a first lens group having a negative refractive power and a second lens group having a positive refractive power in order from object to image sides, an interval between the first and second lens groups changes in a zoom operation, the first lens group is constituted by negative and positive lenses in order from the object to image sides, the negative and positive lenses of the first lens group are arranged at intervals, the second lens group is constituted by three lenses including positive and negative lenses in order from the object to image sides, and a radius of curvature of a lens surface at the object side of the negative lens constituting the first lens group, a shape of a negative lens having the maximum refractive power constituting the second lens group, and a refractive power of the second lens group are appropriately set.

Abstract: A lens driver unit includes a plurality of lens groups including a first lens group and a second lens group, a first lens frame with first and second engaging portions, a second lens frame with a third engaging portion to engage with the first engaging portion, a lens barrel, a first guide element, a second guide element, at least one third guide element, an engaging element, and a drive unit. In an imaging position in which all of the lens groups including the first and second lens groups are placed on an optical axis, the first lens frame is integrally moved with the second lens frame along the optical axis by engagement of the first and third engaging portions while in a contained position, the first lens frame is rotated in a predetermined direction to retreat the first lens group outside an inner diameter of the lens barrel.

Abstract: Disclosed herein is a zoom lens module that may include a first zoom lens group on an optical axis, a second zoom lens group on the optical axis, and a first driving unit configured to move at least one of the first zoom lens group and the second zoom lens group to vary a distance between the first zoom lens group and the second zoom lens group. In the disclosure, the first driving unit may include a first driving motor, a screw member on a rotary shaft of the first driving motor, and a first wire member connecting the screw member to one of the first zoom lens group and the second zoom lens group.

Abstract: A zoom lens includes, sequentially from an object side, a first lens group that is negative; and a second lens group that is positive, where focal length is varied by varying a distance between the first lens group and the second lens group. The first lens group includes, from the object side, a first lens that is a negative biconcave lens having at least one aspherical surface, and a second lens that is a positive meniscus lens having a convex surface facing toward the object side and at least one aspherical surface, and a first condition 0.8<|f1/f2|<1.0 and a second condition 0.5<|r2/f1|<0.8 are satisfied, where f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, r2 is radius of curvature of a surface of the first lens in the first lens group, the surface facing toward an image.

Abstract: A zoom lens includes a first lens group having negative refractive power and a second lens group having positive refractive power, each including at least one plastic aspherical lens. The zoom lens satisfies the following Conditional Expressions (1) and (2), (1) 0.40<fw/bkw<0.60; (2) 0.01<|(X1?X0)/h0|<0.022, where fw: focal length of the entire zoom lens in focus at infinity in a wide-angle end state; bkw: back focus when the entire zoom lens is in focus at infinity in the wide-angle end state; X1: thickness at an image-side effective diameter position of the plastic aspherical lens of the first lens group; X0: thickness at the center of the plastic aspherical lens of the first lens group; and h0: image-side effective radius of the plastic aspherical lens of the first lens group.

Abstract: An optical system has a positive lens group, a negative lens group, and an aperture stop. The negative lens group is disposed at an object side of the aperture stop and has a cemented lens, and in a rectangular coordinate system in which a horizontal axis is Nd and a vertical axis is ?d, when a straight line indicated by Nd=?×?d+? where ?=?0.017 is set, Nd and ?d of at least one lens forming the cemented lens are included in both an area determined by a line when a lower limit value is in a range of expression (1a) and a line when an upper limit value is in a range of the expression (1a), and an area determined by expressions (2a) and (3a): 1.45<?<2.15 (1a); 1.30<Nd<2.20 (2a); and 3<?d<12 (3a); where Nd denotes a refractive index, and ?d denotes an Abbe's number.

Abstract: A zoom lens includes, sequentially from an object side, a first lens group that is negative; and a second lens group that is positive, where focal length is varied by varying a distance between the first lens group and the second lens group. The first lens group includes, from the object side, a first lens that is a negative biconcave lens having at least one aspherical surface, and a second lens that is a positive meniscus lens having a convex surface facing toward the object side and at least one aspherical surface, and a first condition 0.8<|f1/f2|<1.0 and a second condition 0.5<|r2/f1|<0.8 are satisfied, where f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, r2 is radius of curvature of a surface of the first lens in the first lens group, the surface facing toward an image.

Abstract: A zoom lens including a first lens group with a negative refractive power and a second lens group with a positive refractive power is provided. The first lens group is composed of a first lens, a second lens, and a third lens. Refractive powers of the first lens, the second lens, and the third lens are respectively negative, negative, and positive. Moreover, the second lens group is disposed between the first lens group and an image side. The second lens group is composed of a fourth lens, a fifth lens, and a sixth lens. Refractive powers of the fourth lens, the fifth lens, and the sixth lens are respectively positive, negative, and positive. The first lens group and the second lens group are capable of moving between an object side and the image side. The zoom lens has advantages of wide angle and small volume.

Abstract: A zoom lens assembly and zoom lens module are provided, including a first lens, a second lens, a plurality of guiding blocks, a sheathing tube, a plurality of linking members and an adjusting tube. The first lens includes a plurality of curved surfaces disposed on a second lens surface toward a first lens surface. The second lens includes a plurality of driving rods disposed on a third lens surface and abutting the curved surfaces. The guiding blocks are respectively fixed on the first lens. The sheathing tube sheathes the first lens and the second lens and comprises a plurality of guiding notches to receive the guiding blocks, and a plurality of slits. The linking members pass through the slits and are fixed on the second lens. The adjusting tube sheathes the sheathing tube and comprises a plurality of driving notches to receive the linking members.

Abstract: A first group (10) having a negative refractive power, a diaphragm (St) and a second group (20) having a positive refractive power are arranged in order from the object side. Power variation from the wide angle end to the telephoto end is executed by moving the second group (20) to the object side along an optical axis. Correction of an image plane associated with the power variation is made by moving the first group (10) along the optical axis. The second group (20) includes a first lens (L21) having at least one aspheric surface and having a positive refractive power; a cemented lens formed of a second lens (L22) having a positive refractive power and a third lens (L23) having a negative refractive power; a fourth lens (L24) having a negative refractive power; and a fifth lens (L25) having a positive refractive power in order from the object side.

Abstract: In one form, an imaging system comprises an imager that forms an image of an object in a field of view, a rotationally symmetric lens assembly disposed between the imager and the object, and an equalizer. The rotationally symmetric lens assembly provides increased collection efficiency for a given depth of field, whereby the rotationally symmetric lens assembly causes aberration, compared to a well-focused lens. The rotationally symmetric lens assembly comprises a front negative lens, a rear positive lens, and an aperture positioned between the front and rear lenses. The equalizer, which is connected to the imager, receives image data and at least partially compensates for the aberration caused by the rotationally symmetric lens assembly.