Abstract: In order that an image pickup lens etc. may be realized which make it possible to easily realize an arrangement which reduces a possibility of deterioration of an optical characteristic, and which is suitable for a reduction in manufacturing costs and for mass-production, an image pickup lens of the present invention satisfies the following formulas (1) and (2); 1.0<d1/d12<1.8 ??(1); and 0.

Abstract: An optical system (10), in particular a projection objective (12), for microlithography, has an optical axis and at least one optical correction arrangement (44), which has a first optical correction element (48) and at least one second optical correction element, wherein the first correction element is provided with a first aspherical surface contour, and wherein the second correction element is provided with a second aspherical surface contour, wherein the first surface contour and the second surface contour add up at least approximately to zero, wherein the correction arrangement (44) has at least one drive for movement of at least one of the two correction elements. In this case, at least one of the two correction elements can rotate about a rotation axis which is at least approximately parallel to the optical axis, and the at least one drive is a rotary drive for rotation of one or both of the correction elements about the rotation axis.

Abstract: A two-lens type optical lens system for taking image consists two lens elements with refractive power, from the object side: a positive first lens element with a convex object-side surface and a concave image-side surface, both the object-side surface and the image-side surface of the first lens element being aspheric; a positive second lens element with a concave object-side surface and a convex image-side surface, both the object-side surface and the image-side surface of the second lens element being aspheric, and an aperture stop located in front of the first lens element. A focal length of the first lens element is f1, a focal length of the second lens element is f2, a focal length of the optical lens system is f, a radius of curvature of the object-side surface of the second lens element is R3, and they satisfy the relations: f/f1>0.9; (f/f1)>(f/f2)>0.35; and 1/R3<?0.01 mm?1.

Abstract: A high performance fixed focal length optical imaging system for example for a cine camera is operable to receive radiation from an object space and deliver the received radiation through the optical system so as to form an image at an image surface in an image space. The imaging system has the advantage of providing high relative illumination and high contrast at elevated spatial frequencies even when using a fast aperture.

Abstract: To realize an image pickup lens that can be applied to an image pickup module in which a solid-state image sensing device is used, that allows a reduction in manufacturing cost, and that easily maintains its desired resolving power, etc., the second lens has a surface facing the subject, and the surface includes a central portion sticking out toward the subject and a peripheral portion surrounding the central portion and sinking in toward the image surface. Further, the image pickup lens satisfies the mathematical expression 0.30<d1/d<0.45, where d1 is the length of a segment between the center of that surface of the first lens which faces the subject and the center of that surface of the first lens which faces the image surface and d is the whole optical length of the image pickup lens.

Abstract: An imaging optical system consists of, in order from its object side, a front lens group of negative refracting power, and a rear lens group of positive refracting power. A lens component is defined by a lens body having only two surfaces: an object side surface and an image side surface in contact with air on an optical axis. The front lens group comprises, in order from its object side, a first lens component concave on its image side and having negative refracting power, and a second lens component concave on its image side and having negative refracting power. The rear lens group comprises, in order from its object side, a third lens component convex on its object side and having positive refracting power, and a fourth lens component having positive refracting power. The sum of the total number of lens components in the front lens group and the total number of lens components in the rear lens group is 4.

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 fixed-focus lens capable of imaging a light valve disposed at a reduced side onto a magnified side is provided. The fixed-focus lens includes a first lens group, a second lens group, and a free form reflective mirror. The first lens group is disposed in the light path between the reduced side and the magnified side. The second lens group is disposed in the light path between the first lens group and the magnified side and includes a first free form lens. The free form reflective mirror is disposed in the light path between the second lens group and the magnified side. An imaging surface imaged from the light valve by the fixed-focus lens is a curved surface. An imaging system using the fixed-focus lens is also provided.

Abstract: An objective lens for an endoscope, including a negative front lens group and a positive rear lens group arranged such that an aperture stop is positioned therebetween, wherein the front lens group has at least a front-side negative lens and a front-side positive lens arranged in this order from an object side, and the rear lens group has at least a rear-side positive lens and a cemented lens arranged in this order from the object side, the cemented lens being configured by cementing together negative and positive lenses. The objective lens satisfies following conditions: ?4.5?fF/f??2.0 and 1.5?fRP/f?2.5, where fF (unit: mm) represent of the front lens group, f (unit: mm) represents a total focal length of the front lens group and the rear lens group, and fRP (unit: mm) represents a focal length of the rear-side positive lens.

Abstract: An image pickup lens, comprises sequentially from an object side: an aperture stop, a first lens being a positive meniscus lens which has a convex surface at the object side and a concave surface at an image side opposite to the object side, and a second lens having a concave surface at the object side and an image side surface whose radius of curvature on an paraxial region is infinite or a negative value, wherein the first lens is the second lens and the image side surface of the second lens includes an aspheric surface to make a positive power strong toward a lens peripheral region, and wherein the image pickup lens is made to satisfy the following conditional formulas. 1.55<n1<1.80??(1) 0.4<D3/f<0.6??(2) 40.0<?2<90.

Abstract: An optical lens system for taking image comprises, in order from an object side to an image side: a first lens element with positive refractive power having an aspheric convex object-side surface and an aspheric concave image-side surface; a second lens element with positive refractive power having an aspheric convex object-side surface and an aspheric concave image-side surface. Radii of curvature of the object-side surface of the first lens element, the object-side and image-side surfaces of the second lens element are R1, R3 and R4 respectively, focal lengths of the optical lens system for taking image, the first and second lens elements are f, f1, f2 respectively, an on-axis distance between the first and second lens elements is T12, a center thickness of the second lens element is CT2, they satisfy the relations: 0.76 mm?1<1/R1<2.0 mm?1; 0.4<R3/R4<1.15; 0.35<(f/f1)?(f/f2)<0.72; T12/CT2>1.0.

Abstract: This invention provides a compact imaging lens assembly comprising, in order from an object side to an image side: a first lens element with negative refractive power having a convex object-side surface and a concave image-side surface; a second lens element with positive refractive power, at least one of the object-side and image-side surfaces thereof being aspheric; and an aperture stop disposed between the second lens element and an image plane; wherein there are two lens elements with refractive power in the compact imaging lens assembly; and wherein the compact imaging lens assembly satisfies the relations: 0.40<f/f2<1.20, |R3/R4|>1.5. Such an arrangement of optical elements can effectively improve the image quality of the system, reduce the total track length of the lens assembly while maintaining a sufficient back focal length, and achieve a wide field of view.

Abstract: A projection objective of a microlithographic projection exposure apparatus comprises a manipulator for reducing rotationally asymmetric image errors. The manipulator in turn contains a lens, an optical element and an interspace formed between the lens and the optical element, which can be filled with a liquid. At least one actuator acting exclusively on the lens is furthermore provided, which can generate a rotationally asymmetric deformation of the lens.

Abstract: Aspheric lens structures with dual aspheric surfaces and fabrication methods thereof are disclosed. An aspheric lens structure includes a first lens component with an aspheric top surface disposed on a second lens component, wherein the interface between the first lens component and the second lens component is spherical. The second lens component includes an aspheric back surface, wherein the radius of curvature of the aspheric top surface of the first lens component is different than the radius of curvature of the aspheric back surface of the second lens component. The second lens component may also include a planar back surface with a third lens component disposed on the planar back surface of the second component. The third lens component includes an aspheric back surface, wherein the radius of curvature of the aspheric top surface of the first lens component is different than the radius of curvature of the aspheric back surface of the third lens component.

Abstract: The present invention provides a photographing optical lens assembly comprising, in order from the object side to the image side: a first lens element with positive refractive power having a convex object-side surface and a concave image-side surface, the object-side and image-side surfaces thereof being aspheric; a second lens element with negative refractive power having a concave object-side surface and a convex image-side surface, the object-side and image-side surfaces thereof being aspheric; and an aperture stop located in front of the first lens element; wherein an Abbe number of the first lens element is V1, an Abbe number of the second lens element is V2, and they satisfy the relation: |V1?V2|<15; and wherein the number of the lens elements of the photographing optical lens assembly is limited to two. Such an arrangement of optical elements can effectively reduce the volume of the lens assembly and the sensitivity of the optical system and enable the lens assembly to obtain a higher resolution.

Abstract: A fixed-focus lens including a first lens group and a second lens group is provided. The first lens group is disposed between a magnified side and a reduced side and includes a first lens and a second lens arranged in sequence from the magnified side to the reduced side. The refractive powers of both the first lens and the second lens are negative, and the first lens is an aspheric lens. The second lens group is disposed between the first lens group and the reduced side and includes a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged in sequence from the magnified side to the reduced side. The refractive powers of the seven lenses from the third lens to the ninth lens are respectively positive, negative, positive, negative, positive, negative, and positive in sequence.

Abstract: Disclosed is a wide-angle lens having a viewing angle of more than 130°. The wide angle lens has a front group, an aperture, and a rear group arranged in this order from an object side to an image side. The front group has a first lens as a negative lens, a second lens as a negative lens, and a third lens as a positive lens arranged from the object side to the image side. The rear group is a cemented lens having a positive power when two lenses are bonded to each other. The wide-angle lens constitutes an image forming system with the five lenses as a whole, the first lens and the second lens of the front group are aspherical lenses, and the third lens is a spherical lens.

Abstract: A lens system with a lens formed of a material having a negative index of refraction in an operational frequency range, a first surface of the material having a convex hyperbolic curvature, and a second surface of the material having a concave circular curvature. A lens system can include two of these lenses, arranged with the concave circular surfaces facing each other. Far field radiation arriving at the hyperbolic surface of the the first lens is refracted by the lens material toward the circular surface, out of the first lens in a direction parallel to the original radiation direction, and into the circular surface of the second lens, where it is refracted toward the hyperbolic surface of the second lens, and exits the second lens in a direction parallel to the original direction. The lens material can have a tunable or fixed negative refractive index and/or resonant frequency.

Abstract: A miniature image capture lens is disclosed, comprising a wafer scale lens system, which comprises a first lens group including a first substrate, a first surface disposed on a first side of the first substrate, a second surface disposed on a second side of the first substrate, and a second lens group including a second substrate, a third surface disposed on a first side of the second substrate, and a fourth surface disposed on a second side of the second substrate, wherein the first surface, the second surface, the third surface and the fourth surface are aspherical, one of the first surface and the second surface, and one of the third surface and the fourth surface have a high refraction index Nd_h and a high abbe number Vd_h, another one of the first surface and the second surface, and another one of the third surface and the fourth surface have a low refraction index Nd_l and a low abbe number Vd_l, and the miniature image capture lens meets the following conditions: Nd—h=1.58˜1.62; Nd—l=1.48˜1.

Abstract: A fixed-focus lens adapted to be disposed between a primary image side and a second image side is provided. The fixed-focus lens includes a second lens group, a first lens group, and a curved reflector arranged in sequence from the primary image side to the second image side. The second lens group includes a first lens, a second lens, and a third lens arranged in sequence from the primary image side to the second image side. The first lens and the third lens have positive refractive powers and each of the first lens, the second lens, and the third lens is a spherical lens.

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 wide angle optical system includes: a first lens group of negative refractive power; and a second lens group of positive refractive power; the first lens group and the second lens group being arranged in the above-mentioned order from the object side; the second lens group including: a cemented doublet SU21; an aperture diaphragm; a lens SU22; and a biconvex lens L25; the cemented doublet, the aperture diaphragm, the lens and the biconvex lens being arranged in the above-mentioned order from the object side; the largest ones of the air spaces on the axis being the front and rear spaces of the aperture diaphragm except the back focal length; the wide angle optical system being divided into the first lens group and the second lens group at the second largest air space operating as a boundary.

Abstract: A wide-angle optical system comprises a front lens group (11), and a rear lens group (12), with an aperture stop (13) interposed between. The front lens group (11) includes at least two negative lenses (111, 112) and at least one positive lens (113). At least one of the positive lenses included in the front lens group (11) has at least one aspherical surface. The front lens group (11) satisfies the conditional expression vdp<29 where vdp is the minimum value of the Abbe number of the positive lens(es) included in the front lens group (11).

Abstract: A wide-angle lens 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. The first lens group includes at least one negative meniscus lens having a convex surface facing the object side. The second lens group includes, in order from the object side, a positive lens, a negative lens and a positive lens. Given conditional expressions are satisfied.

Abstract: The present invention provides a photographing optical lens assembly comprising, in order from the object side to the image side: a first lens element with positive refractive power having a convex object-side surface and a concave image-side surface, the object-side and image-side surfaces thereof being aspheric; a second lens element with negative refractive power having a concave object-side surface and a convex image-side surface, the object-side and image-side surfaces thereof being aspheric; and an aperture stop located in front of the first lens element; wherein an Abbe number of the first lens element is V1, an Abbe number of the second lens element is V2, and they satisfy the relation: |V1?V2|<15; and wherein the number of the lens elements of the photographing optical lens assembly is limited to two. Such an arrangement of optical elements can effectively reduce the volume of the lens assembly and the sensitivity of the optical system and enable the lens assembly to obtain a higher resolution.

Abstract: A fixed-focus lens adapted to be disposed between a magnified side and a reduced side is provided. The fixed-focus lens includes a first lens group, a second lens group, and a third lens group. The first lens group disposed between the magnified side and the reduced side includes three lenses and has a negative refractive power. The second lens group disposed between the first lens group and the reduced side includes five lenses and has a positive refractive power. The third lens group disposed between the second lens group and the reduced side includes five lenses and has a positive refractive power. The fixed-focus lens satisfies |F1/F|<1.35, 3.5<|F2/F|<4.5, and 4<|F3/F|<5, wherein F1 is the effective focal length (EFL) of the first lens group, F2 is the EFL of the second lens group, F3 is the EFL of the third lens group, and F is the EFL of the fixed-focus lens.

Abstract: An exemplary projection lens includes, in this order from the magnification side to the minification side thereof, a negative lens group of negative fraction power, and a positive lens group of positive fraction power. The projection lens satisfies the formulas of: ?2.5<F1/F<?1.5; and 1.3<F2/F<1.5, where F1, F2, and F respectively represent the effective focal lengths of the negative lens group, the positive lens group, and the projection lens.

Abstract: A configuration where a first group having a positive refractive power and a positive second group having a positive refractive power are placed sequentially from the object side is basically used. As the first group, a wide-angle first group and a telephoto first group are selectively switched over to be placed on the optical axis, thereby switching over the focal length between the wide-angle side and the telephoto side. Since the configuration in which the first group placed on the object side is switched is employed, adherence of dust or the like to the imaging surface due to the switching of the focal length can be prevented from occurring. Each group is configured by a minimum number of lenses. The whole system has a configuration which has a reduced number of lenses, and which is small and simple.

Abstract: A wide angle lens especially suitable for digital single lens reflex cameras is described. The lens offers the advantages of superior performance while using fewer lens elements thus reducing size and cost to manufacture. The lens consists of two lens groups separated by an aperture stop. The first lens group consists of a meniscus lens and the novel use of a bi-concave lens element. The first group may also include a cemented doublet with novel ratios of refractive index and Abbe numbers. Embodiments of the wide angle lens satisfy conditional equations of 6?BFL/f?7.5 and 10<?d/f?21, where BFL is the distance from the most image side lens element surface to the image plane with the lens focused at infinity, f is the effective focal length of the wide angle lens and ?d is the distance from the most object side lens element surface to the most image side lens element surface.

Abstract: A compatible near field optical recording/reproducing apparatus includes a solid immersion lens unit including a first lens, which has an aspherical surface in which light incident from the first light source is condensed, and a second lens, which realizes a high numerical aperture via a near field effect by light condensed by the first lens and has an aspherical surface. An effective beam size-controlling device controls an effective size of a light beam transmitted to the solid immersion lens unit such that either near field light or far field light is transmitted to an information storage medium by the solid immersion lens unit and a focal point adjusting optical system adjusts a focal position of light transmitted to the information storage medium according to the type of the information storage medium.

Abstract: An imaging optical system consists of, in order from its object side, a front lens group of negative refracting power, and a rear lens group of positive refracting power. A lens component is defined by a lens body having only two surfaces: an object side surface and an image side surface in contact with air on an optical axis. The front lens group comprises, in order from its object side, a first lens component concave on its image side and having negative refracting power, and a second lens component concave on its image side and having negative refracting power. The rear lens group comprises, in order from its object side, a third lens component convex on its object side and having positive refracting power, and a fourth lens component having positive refracting power. The sum of the total number of lens components in the front lens group and the total number of lens components in the rear lens group is 4.

Abstract: Providing an optical system having a large aperture ratio, a long back focal length, high optical performance with excellently correcting various aberrations, and an optical apparatus equipped with the optical system. The system includes, in order from an object along an optical axis of the optical system, a first lens group having positive refractive power, and a second lens group having positive refractive power. The second lens group includes a negative lens, a first positive lens, and a second positive lens, and the optical system includes a compound type aspherical lens constructed by a glass material and a resin material.

Abstract: An imaging optical system includes: an object-side lens group having, in order from its object side, an object-side positive meniscus lens that is convex on its object side and has positive refracting power, and an object side negative meniscus lens that is convex on its object side and has negative refracting power; and image-side lens group having, in order from its object side, an image-side negative lens, an image-side first positive lens and an image-side second positive lens. The image-side negative lens and the image-side first positive lens adjacent thereto form together a cemented doublet.

Abstract: A projection-type display apparatus, comprises a front lens group having a plural number of lenses, each having rotationally symmetric surface configuration, a rear lens group, being disposed in rear of the front lens group, including a refractive lens for diverting a light and having a rotationally symmetric surface configuration, and a plural number of free curved surface lenses, each having a rotationally asymmetric free curved surface configuration, and a reflection mirror, being disposed in rear of the rear lens group, having a convex configuration into a direction of reflection of light and a rotationally asymmetric free curved surface configuration, at least in a part thereof.

Abstract: A compact short back focus imaging lens system with two lenses is revealed and includes along the optical axis from an object side to an image side: an aperture stop, a first lens with positive refractive power that is a meniscus aspherical lens with convex surface facing the object side, a second lens with negative refractive power that is a meniscus aspherical lens with convex surface facing the image side, an IR cut-off filter and an image sensor. Moreover, the following conditions are satisfied by the imaging lens system: - 0.3 ? f 1 f 2 ? - 0.01 0.25 ? bf TL ? 0.4 wherein f1 is focal length of the first lens, f2 is focal length of the second lens, bf is back focal length of the imaging lens system, and TL (overall length) is the distance from the aperture stop to the image plane.

Abstract: An imaging lens system, in order from the object side to the image side thereof, includes a first lens with positive refractive power, and a second lens with positive refractive power. The imaging lens system satisfies the following formulas: 1.2?TTL/f?2.0, where image sensing element TTL is the distance along an optical axis thereof from the object-side lens surface of the first lens to an imaging plane, f is the focal length of whole the image lens system.

Abstract: An image pickup lens includes a first lens block with a positive power and a second lens block with a positive or negative power. The first lens block includes a first lens substrate, and lens portions 1a and 1b arranged on opposing surfaces of the first lens substrate. The lens portions 1a and 1b are different from the first lens substrate in at least one of a refractive index and an Abbe number. The second lens block includes a second lens substrate, and lens portions 2a and 2b arranged on opposing surfaces of the second lens substrate. The lens portions 2a and 2b are different from the second lens substrate in at least one of a refractive index and an Abbe number. The image pickup lens satisfies a condition relating to focal lengths of the lens portions 1a and 2b.

Abstract: A high performance fixed focal length optical imaging system for example for a cine camera is operable to receive radiation from an object space and deliver the received radiation through the optical system so as to form an image at an image surface in an image space. The imaging system has the advantage of providing high relative illumination and high contrast at elevated spatial frequencies even when using a fast aperture.

Abstract: A lens unit includes a front group, a stop, and a rear group, in order from the object side toward the image side. The front group includes at least: a first lens having a negative meniscus shape; a negative second lens formed from a plastic and having an aspherical surface; and a positive third lens, in order from the object side toward the image side. The rear group includes at least: a positive first lens; and a negative second lens, in order from the object side toward the image side.

Abstract: An image system adapted to a projection display apparatus includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, an aspheric reflector, and a curved reflector. The second lens group includes an aspheric lens which is the nearest to the light valve in the second lens group. A material of the aspheric lens includes glass, the thermal-optical coefficient of the glass is between 1.0×10?6/K and 12.5×10?6/K, and the refractive index of the glass is between 1.482 and 1.847. The aspheric reflector is disposed front of the first lens group for reflecting the image beam passing through the first lens group and second lens group. The curved reflector is disposed above the first lens group for reflecting the image beam reflected by the aspheric reflector onto the screen. The image system has a good imaging quality.

Abstract: An imaging lens has a compact shape and sufficiently compensates for various aberrations. The imaging lens includes a first lens, a second lens, and a third lens disposed sequentially, with the first lens toward an object. The conditions “0.5H<T0<0.7H,” “2<?r4/?<2.5,” and “0.15<?r5/?<0.3” are satisfied, where: H is the effective radius of the surface of the third lens facing an image surface; T0 is the distance between the optical axis and a point on a line parallel to the optical axis and normal to the surface of the third lens facing the image surface; ? is the combined refractive power of the imaging lens; ?r4 is the refractive power of the surface of the second lens facing the image surface; and ?r5 is the refractive power of the surface of the third lens facing the object.

Abstract: An image forming optical system which comprises a negative lens unit and a positive lens unit arranged in order from an object side. The negative lens unit includes, in order from the object side, a first negative lens and a second negative lens, or a first negative lens, a second negative lens and a third negative lens. The positive lens unit includes, in order from the object side, a third positive lens, a fourth negative lens, a fifth positive lens and a sixth positive lens, or a fourth positive lens, a fifth negative lens, a sixth positive lens and a seventh positive lens.

Abstract: An imaging lens of which optical performance does not deteriorate even in a high temperature environment, various aberrations are well corrected, optical length is short, and back focus is sufficiently secured. This imaging lens comprises a first diaphragm S1, a first junction type compound lens 14, a second diaphragm S2 and a second junction type compound lens 16, wherein the first diaphragm, the first junction type compound lens, the second diaphragm, and the second junction type compound lens are arranged in this sequence from an object side to an image side. The first junction type compound lens comprises a first lens L1, a second lens L2 and a third lens L3 arranged in this sequence from the object side to the image side, and the second junction type compound lens comprises a fourth lens L4, a fifth lens L5 and a sixth lens L6 in this sequence from the object side to the image side. The first lens, the third lens, the fourth lens and the sixth lens are formed of a curable resin material.

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: A lens system includes a first lens and a second lens formed in turn from an object side to an image side. The lens system satisfies the following conditions: 0.08?D2/D?0.14??(1) 4?h2/z2?12??(2) wherein, D2 is the distance along an optical axis of the lens system from the second surface of the first lens to the third surface of the second lens, D is the distance along an optical axis of the lens system from the first surface of the first lens to fourth surface of the second lens, h2 is the distance from the optical axis of the lens system to the outermost optically effective portion of the second lens surface of the first lens, and z2 is the distance along the optical axis of the lens system from the vertex of the second surface of the first lens to the point of the optical axis where h2 is measured.

Abstract: An imaging lens includes a first lens group having a positive refractive power, an aperture stop, and a second lens group having a positive refractive power, which are disposed in order from an object. The first lens group has a first lens component having a negative refractive power and a second lens component having a positive refractive power, which are disposed in order from the object, and conditions expressed by the expressions 0.12<f/f1<0.47 and 0.016<D12/f<0.079 are satisfied, when f1 is a focal length of the first lens group, f is a focal length of the imaging lens, and D12 is an air distance between the first lens component and the second lens component of the first lens group.

Abstract: The invention relates to an image pickup system comprising an electronic view finder suitable for achieving compactness and having a sufficient viewing angle of field and satisfactory optical performance. The image pickup system comprises an image pickup device, an image display device for displaying an image, a controller for converting image formation obtained from the image pickup device into a signal that enables the image information to be formed on the image display device, and a viewing optical system for guiding an image displayed on the display device to a viewer's eye. The viewing optical system comprises at least three lenses.

Abstract: A lens system includes a first lens and a second lens formed in turn from an object side to an image side. The lens system satisfies the following conditions: 0.08?D2/D?0.14??(1) 4?h2/z2?12??(2) wherein, D2 is the distance along an optical axis of the lens system from the second surface of the first lens to the third surface of the second lens, D is the distance along an optical axis of the lens system from the first surface of the first lens to fourth surface of the second lens, h2 is the distance from the optical axis of the lens system to the outermost optically effective portion of the second lens surface of the first lens, and z2 is the distance along the optical axis of the lens system from the vertex of the second surface of the first lens to the point of the optical axis where h2 is measured.

Abstract: A lens assembly includes, in order from an object side toward an image side along an optical axis thereof, a first lens having positive refractive power, and a second lens. The lens assembly satisfies the following conditions: 0<|f1/f|<2 and 0<|f2/f|<7, wherein f is an effective focal length of the lens assembly, f1 is an effective focal length of the first lens, and f2 is an effective focal length of the second lens. The first lens has at least one spherical surface, thus effectively decreasing the production cost of the lens assembly.

Abstract: A fixed focal length lens system comprises a first lens unit and a second lens unit. The first lens unit comprises a plastic negative lens, wherein the first lens unit has a negative diopter, and the plastic negative lens comprises at least one non-spherical surface. The second lens unit comprises a plastic positive lens, wherein the second lens unit has a positive diopter. The fixed focal length lens system satisfies the equation: ?1<2Gf/1Gf<0, wherein 1Gf is the focal length of the first lens unit and 2Gf is the focal length of the second lens unit.