Abstract: This invention provides an image capturing lens assembly in order from an object side to an image side comprising: a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power; a third lens element with negative refractive power having a concave object-side surface; a fourth lens element having a concave object-side surface and a convex image-side surface; and a fifth lens element having a concave image-side surface, the object-side and image-side surfaces thereof being aspheric and at least one inflection point being formed on at least one of the object-side and image-side surfaces thereof. By such arrangement, it can effectively reduce the aberration as well as the total track length of the imaging lens system for obtaining higher image resolution.

Abstract: An imaging lens includes: an aperture stop; a biconvex first lens directing convex surfaces toward an object and an image; a second lens directing a convex surface toward the object near the optical axis and having negative refractive power; a biconvex third lens directing convex surfaces toward the object and the image near the optical axis; a fourth lens directing a concave surface toward the object near the optical axis and having positive refractive power; and a fifth lens directing a convex surface toward the object near the optical axis and having negative refractive power. The aperture stop and the first to fifth lenses are arranged in this order from the object side, and a conditional expression 1 being 0.50<f1/f<0.76 is satisfied, where f1 represents the focal length of the first lens and f represents the focal length of the entire imaging lens.

Abstract: An imaging lens includes, sequentially from an object side, a positive first lens; a negative second lens; a positive third lens having a convex surface on an image plane side; a fourth lens that is a meniscus lens having a convex surface on the image plane side; and a fifth lens having a refractive power that gradually changes from negative at the lens center to positive at the lens periphery, where the first lens and the second lens are disposed having an interval therebetween.

Abstract: This invention provides an imaging lens system including, in order from an object side to an image side: a first lens with positive refractive power having a convex object-side surface; a second lens with negative refractive power; a third lens having a concave image-side surface; a fourth lens with positive refractive power; a fifth lens with negative refractive power having a concave image-side surface, at least one surface thereof having at least one inflection point; and an aperture stop disposed between an imaged object and the third lens. The on-axis spacing between the first lens and second lens is T12, the focal length of the imaging lens system is f, and they satisfy the relation: 0.5<(T12/f)×100<15.

Abstract: A macro-lens system and a photographing apparatus having the macro-lens system. The macro-lens system includes: first, second, third, fourth, and fifth lens groups which are arranged in order from an object side to an image side, wherein the first lens group has a positive refractive power and is fixed during focusing, the second lens group has a negative refractive power and is moved during focusing, the third lens group has a positive refractive power and is fixed during focusing, the fourth lens group has a positive refractive power and is moved during focusing, and the fifth lens group has a negative refractive power.

Abstract: An image pickup optical system made of five lenses, includes in order from an object side, an aperture stop, a first lens L1 having a positive refracting power, a second lens L2 having a negative refracting power, a third lens L3 having a positive refracting power, a fourth lens L4 having a positive refracting power, and a fifth lens L5 having a negative refracting power. Moreover, an image pickup apparatus includes this image pickup optical system.

Abstract: An image pickup optical lens assembly, sequentially arranged from an object side to an image side along an optical axis, comprises the first lens element with positive refractive power having a convex object-side surface, the second lens element with negative refractive power having a concave object-side surface and a convex image-side surface, the third lens element with refractive power, the fourth lens element with positive refractive power having a concave object-side surface and a convex image-side surface, the fifth lens element with negative refractive power having a concave image-side surface with at least one inflection point, and a stop. Each of the five lens elements may be made of plastic with bi-aspherical surfaces. Additionally, the image pickup optical lens assembly satisfies conditions of shortening the total length and reducing the sensitivity for usage in compact cameras and mobile phones with camera functionalities.

Abstract: An image pickup optical lens assembly, sequentially arranged from an object side to an image side along an optical axis, comprising: the first lens element with positive refractive power having a convex object-side surface, the second lens element with negative refractive power, the third lens element with refractive power, the fourth lens element with positive or negative refractive power having a concave object-side surface and a convex image-side surface with both being aspheric, and the fifth lens element with positive or negative refractive power having a convex object-side surface and a concave image-side surface with both being aspheric. Additionally, the image pickup optical lens assembly satisfies conditions related to the reduction of the total length and the sensitivity of the image pickup optical lens assembly for compact cameras and mobile phones with camera functionalities.

Abstract: An optical unit includes a first lens, a second lens, a diaphragm, a third lens, a fourth lens, and a fifth lens, which are arranged in the stated order from an object side to an image plane side. The second lens has a convex shape. The third lens has a meniscus shape. The fourth lens has a convex shape. The fifth lens has a negative power.

Abstract: A zoom lens comprises, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit, and a fourth lens unit having a positive refractive power. The fourth lens unit includes a forty-first lens unit having a negative refractive power and arranged at the object side with reference to the longest air gap and a forty-second lens unit having a positive refractive power and arranged at the image side with reference to the air gap. The forty-first lens unit includes a negative 411st lens, and the forty-second lens unit includes a positive 421st lens. Abbe numbers and partial dispersion ratios of materials of the 411st lens and the 421st lens ?d411, ?gF411, ?d421 and ?gF421 are appropriately set.

Abstract: An optical system comprising two lens cells, each lens cell comprising multiple lens elements, to provide imaging over a very wide image distance and within a wide range of magnification by changing the distance between the two lens cells. An embodiment also provides scannable laser spectroscopic measurements within the field-of-view of the instrument.

Abstract: The present invention relates to an optical unit. The present invention further relates to the use of such an optical unit. Such an optical unit comprises, seen in a direction from the object side to the imaging surface, a first substrate, a first lens element, a flat, transparent intermediate layer, a second lens element and a second substrate, which intermediate layer has an optically correcting function near the imaging surface.

Abstract: An imaging lens includes plastic-made first, second, third, fourth, and fifth lens elements arranged in the given order from an object side to an imaging side, each having object-side and imaging-side surfaces facing toward the object and imaging sides, respectively. The first lens element has a positive focusing power, and the object-side surface thereof is a convex surface. The second lens element has a negative focusing power, and the imaging-side surface thereof is a concave surface. The third lens element has a positive focusing power, and each of the imaging-side and object-side surfaces thereof is a convex surface. The fourth lens element is a meniscus lens, and the imaging-side surface thereof is a convex surface. The imaging-side surface of the fifth lens element has a concave area in a vicinity of an optical axis of the fifth lens element.

Abstract: Disclosed herein is a zoom lens including a first lens group, a second lens group, a third lens group, a fourth lens group, and a fifth lens group. The zoom lens satisfies following conditional expressions (1) and (2), 0.03<H1?/f1<0.3??(1) 0.3<|f2|/?(fw·ft)<0.65??(2) where H1? is an interval from a vertex of a surface nearest to the image side in the first lens group to a principal point on the image side of the first lens group (? denotes the object side, and + denotes the image side), f1 is focal length of the first lens group, f2 is focal length of the second lens group, fw is focal length of an entire lens system at a wide-angle end, and ft is the focal length of the entire lens system at a telephoto end.

Abstract: The present invention provides an imaging lens assembly including, in order from an object side to an image side: a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power; a third lens element with negative refractive power; a fourth lens element with positive refractive power having a convex object-side surface; a fifth lens element having a concave image-side surface, at least one inflection point being provided on the fifth lens element; and an aperture stop disposed between an imaged object and the third lens element. Such an arrangement of optical elements can effectively improve the image quality of the system and enable the imaging lens assembly to maintain a compact form. When the aperture stop is disposed near the object side, the telecentric feature is emphasized, resulting in a shorter total track length.

Abstract: A projection objective suitable for immersion microlithography is designed as a single-waist system with five lens groups, and has a first lens group of negative refractive power, a second lens group of positive refractive power, a third lens group of negative refractive power, a fourth lens group of positive refractive power and a fifth lens group of positive refractive power. The fourth lens group has an entrance surface (E) that lies in the vicinity of a point of inflection of a marginal ray height between the third lens group (LG3) and the fourth lens group (LG4). No negative lens of substantial refractive power is arranged between the entrance surface and the system diaphragm (5). Embodiments of inventive projection objectives achieve a very high numerical aperture NA>1 in conjunction with a large image field and are distinguished by a compact design size.

Abstract: An optical system comprising two lens cells, each lens cell comprising multiple lens elements, to provide imaging over a very wide image distance and within a wide range of magnification by changing the distance between the two lens cells. An embodiment also provides scannable laser spectroscopic measurements within the field-of-view of the instrument.

Abstract: The invention relates to an optical system (10) that comprises a plurality of lenses (12) distributed into a first group (13) including at least two lenses (12) and a second group (14) including at least two lenses (12), wherein at least one lens (12) of the first group (13) is provided over a corresponding lens (12) of the second group (14). The optical system (10) is provided with a means (20) for guiding the light rays (11) entering inside any lens (12) of the first group (13) towards the corresponding lens (12) of the second group (14).

Abstract: An imaging lens includes, in order from an object side, a first lens having a negative power and including a concave image-side surface, a second lens having a positive power, a stop, a third negative lens, which is a biconcave lens, a fourth lens having a positive power, and a fifth lens having a positive power and including a convex image-side surface. The imaging lens satisfies the following conditional expressions: 0.18<(D4+D5)/f<0.44, and 0.18<D1/f where f denotes a focal length of an entire lens system, D1 denotes a thickness of a center of the first lens, D4 denotes a distance from an image-side surface of the second lens to the stop on an optical axis, and D5 denotes a distance from the stop to an object-side surface of the third lens on the optical axis.

Abstract: A purely refractive projection objective suitable for immersion microlithography is designed as a single-waist system with five lens groups in the case of which a first lens group of negative refractive power, a second lens group of positive refractive power, a third lens group of negative refractive power, a fourth lens group of positive refractive power and a fifth lens group of positive refractive power are provided. The fourth lens group has an entrance surface (E) that lies in the vicinity of a point of inflection of a marginal ray height between the third lens group (LG3) and the fourth lens group (LG4). No negative lens of substantial refractive power is arranged between the entrance surface and the system diaphragm (5). Embodiments of inventive projection objectives achieve a very high numerical aperture NA>1 in conjunction with a large image field and are distinguished by a compact design size.

Abstract: It is provided that an imaging lens having satisfactory optical performances and being reduced in size and cost. The imaging lens includes in order from an object side, a negative first lens, a negative second lens, a positive third lens, a stop, a positive fourth lens and a negative fifth lens L5. And the focal length f3 of the third lens at d-line, the focal length f of the whole system at d-line satisfy 3.0<f3/f<4.5.

Abstract: A small projection lens includes a first lens, which is a biconvex lens, an aperture, an aperture diaphragm (or an aperture), a second lens, which is a negative meniscus lens having a concave surface facing a magnification side, a third lens, which is a positive meniscus lens having a convex surface facing a reduction side, and a fourth lens, which is a biconvex lens having aspheric surfaces at both sides on an optical axis, arranged in this order from the magnification side. A minimum portion of the length of all lens elements of the small projection lens in a diametric direction vertical to the optical axis is equal to or less than 15 mm, and the small projection lens satisfies the following conditional expression: 2.5<?/S<10.0 (where S indicates the maximum length of a magnification-side image (inch) and ? indicates a magnifying power).

Abstract: An imaging lens module includes a fixed diaphragm and an optical module. The optical module includes first, second, third, fourth and fifth lenses arranged from an object side to an image side in a sequence of: the first lens, having a negative refractive power, a convex surface disposed towards the object side, and a concave surface disposed towards the image side; the diaphragm; the second lens having a positive refractive power and a convex lens disposed towards the image side; and the third lens; being a meniscus negative lens; the fourth lens, being a positive lens, and adhered with the third lens to form a composite lens; the fifth lens, having a positive refractive power, such that the imaging lens module is a lens module with the features of high imaging quality and high yield rate.

Abstract: A zoom lens configured by arranging a first lens group, a second lens group, a third lens group, a fourth lens group, and a fifth lens group in order from the object side to the image side, and further having an aperture diaphragm on the object side of the third lens group. In the first lens group, a first lens, a second lens, and a third lens are located in order from the object side to the image side. In the second lens group, a fourth lens, a fifth lens, and a sixth lens are located in order from the object side to the image side. The third lens group is made up of a seventh lens which is a convex lens, the fourth lens group is made up of at least two or more cemented lenses, the third lens group and the fourth lens group include at least one surface formed into an aspherical surface.

Abstract: A zoom lens having five lens groups arranged in succession. The zoom lens is configured such that when zooming from a short focal length end toward a long focal length end, the second lens group lens moves toward the third lens group and the fourth lens group moves toward a side of the third lens group, and the fifth lens group corrects the zooming and a shift in a position of an imaging plane of the zoom lens caused by movement of the third lens group and the fourth lens group.

Abstract: A compact zoom lens optical system suitable for use in a camera using a solid state photographing device and providing excellent correction of color aberrations, high zooming ratio, and telecentricity. The zoom lens optical system includes: a first lens group having a positive refractive power, the first lens group including two lenses; a second lens group having a negative refractive power; a third lens group having a positive refractive power; a fourth lens group having a positive refractive power; and a fifth lens group having a positive refractive power. The first through fifth lens groups are sequentially arranged from an object side and the first lens group is moved during zooming from a wide angle position to a telephoto position.

Abstract: A zoom lens with a reduced thickness and size in the depthwise direction consists of a plurality of lens groups (GR1 to GR5), so that it varies in power in response to variation in intervals between the lens groups. The zoom lens also has a prism G2 to bend the optical axis passing through the lens groups (GR1 to GR5). The last lens group G5 (counted from the object side) is composed of a negative lens group and a positive lens group, with an air layer interposed between them (arranged sequentially from the object side). The present invention also provides an imaging device equipped with an imaging element to convert the optical images formed by said zoom lens into electrical signals.

Abstract: A purely refractive projection objective suitable for immersion micro-lithography is designed as a single-waist system with five lens groups, in the case of which a first lens group with a negative refracting power, a second lens group with a positive refracting power, a third lens group with a negative refracting power, a fourth lens group with a positive refracting power and a fifth lens group with a positive refracting power are provided. The system aperture is in the region of maximum beam diameter between the fourth and the fifth lens group. Embodiments of projection objectives according to the invention achieve a very high numerical aperture of NA>1 in conjunction with a large image field, and are distinguished by a good optical correction state and moderate overall size. Pattern widths substantially below 100 nm can be resolved when immersion fluids are used between the projection objective and substrate in the case of operating wavelengths below 200 nm.

Abstract: Disclosed is a zoom lens which is composed of a plurality of groups of lenses and which varies the power thereof by changing inter-group spacings. The zoom lens is configured such that: the last group of lenses that is located at the end of an image space and is negatively refractive is held stationary in optical-axis directions during variation of the power of the zoom lens, and includes a front group of negative lenses and a rear group of positive lenses; and the rear group of positive lenses or part of the rear group of positive lenses (hereinafter, referred to as a group of blur compensation lenses) is movable in directions orthogonal to the optical axis of the zoom lens. In this configuration, the group of blur compensation lenses is moved in the directions orthogonal to the optical axis in order to shift an image.

Abstract: The invention discloses a macro lens that takes a retrofocusing function for the purpose of downsizing. The macro lens employs a floating mechanism to cover a wide photographing range from the equi-magnification to the infinity, and especially, attains a great imaging performance by appropriately compensating for spherical aberration, comatic aberration, and chromatic aberration of magnification. The macro lens comprised of first to fifth lenses in the order closer to the object; that is, the first lens serving as a negative meniscus lens with a convex surface oriented to the object, the fourth lens as a negative lens with a concave surface of great curvature oriented to the image plane, and the fifth lens as a negative lens with a surface of great curvature oriented to the object. The macro lens satisfies conditions as expressed in the following formulae: 0.6?F1/F?1.3 ??(1) 0.9?F4/F5?1.

Abstract: An imaging lens is provided and includes: a positive first lens with a convex surface directed to the object side; a second lens having a negative meniscus shape with a concave surface directed to the image side; a third lens having a positive meniscus shape with a convex surface directed to the image side; a negative fourth lens with both surfaces being an aspheric surface and the image-side surface being concave in the proximity of the optical axis; and a positive or negative fifth lens with both surfaces being an aspheric surface, in order from the object side. The following conditional expressions are satisfied as for Abbe numbers vd1 and vd2 of the first lens and the second lens and Abbe number vd4 of the fourth lens.

Abstract: A zoom lens with a wide angle of view and a high zooming ratio and a camera employing the zoom lens. 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, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power, wherein the first through fifth lens groups are sequentially arranged from an object side toward an image side. The first through fifth lens groups are moved during zooming between wide angle position to telephoto position in a manner that increases the distances between the first and second lens groups, between the third and fourth lens groups, and between the fourth and fifth lens groups and decreases a distance between the second and third lens groups.

Abstract: A zoom lens includes, in order from an object side to an image side: 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 an aperture stop; a fourth lens unit having negative optical power; and a fifth lens unit having positive optical power, in which, during zooming from a wide-angle end to a telephoto end, the first lens unit stays, the second lens unit moves toward the image side, and the third lens unit moves together with the aperture stop.

Abstract: A zoom lens has first to fifth lens groups G1 to G5 having positive, negative, positive, positive, and negative refractive power, in order from an object side. The first lens groups G1 includes a prism L2 for bending a light path. Zooming is performed by adjusting a focal length by linear movement of the second lens group G2 and fourth lens group G4 and compensating an image surface position by nonlinear movement of the fifth lens group G5. Focusing is performed by moving the fifth lens group G5.

Abstract: A zoom lens system, in sequence from an object side to an image side, includes a first lens group having positive refractive power and fixed for gathering incoming light; a second lens group having negative refractive power for changing a focal length of the zoom lens system; a third lens group having positive refractive power and made stationary; a fourth lens group having positive refractive power and movable for compensating for a fluctuation of an image plane position; and a fifth lens group having positive refractive power and movable for focusing purpose. During zooming from a wide-angle end to a telephoto end, the second and fourth lens groups are moved independently toward the third lens group in such a manner that spacing between the first lens group and the second lens group increases and spacing between the third lens group and the fourth lens group decreases.

Abstract: An afocal zoom lens for microscopes includes five lens units having, in order from the object side, positive, negative, negative, positive, and negative refracting powers. When the magnification of the afocal zoom lens is changed in the range from a low-magnification position to a high-magnification position, a first lens unit and a fifth lens unit are fixed, a second lens unit is moved toward the image side, and a fourth lens unit is moved toward the object side. The afocal zoom lens satisfies the following condition: 0?F2/F3?2.5 where the focal length of the second lens unit is represented by F2 and the focal length of a third lens unit is represented by F3. The third lens unit is constructed with at least one negative lens with a concave surface facing the object side.

Abstract: A zoom lens optical system includes a first optical group with a first lens having negative refraction, a second lens having positive refraction, and a light path changing unit to change the path of an incident light passing through the first lens to have light incident on the second lens. A second optical group is provided for varying magnification. The second optical group has a third lens having negative refraction, a fourth lens, and a fifth lens, wherein the fourth and fifth lenses are integrally connected and have negative refraction. A third optical group includes an iris diaphragm, a sixth lens having positive refraction, and a seventh lens having negative refraction. A fourth optical group is provided for focusing. The fourth optical group has an eighth lens and a ninth lens being integrally connected and both having positive refraction.

Abstract: A lens assembly includes, in order from an object side to an image side: a first lens; a first meniscus lens in optical communication with the first lens; a second meniscus lens in optical communication with the first meniscus lens; an aperture stop in optical communication with the second meniscus lens; a fourth lens in optical communication with the aperture stop; and a bi-convex lens in optical communication with the fourth lens. The lens assembly is a four group, five element, lens assembly that is constructed so that at least one of the lenses may be replaced without also requiring the other lenses in the assembly to be significantly changed, resulting in a “flexible” construction. The lens assembly may be adapted to provide a field of view of approximately 15 degrees; approximately 0% vignetting within the field of view; and a distortion of the image of less than approximately 1%. Multiple lens assemblies and detectors may be provided in a single housing.

Abstract: A projection lens, for enlarging and projecting a picture formed on a flat fluorescent plate of a CRT projection tube, includes: a first lens unit of a plus lens, having aspheric surfaces on both surfaces, being convex to the screen side at a central portion including an optical axis, a second lens unit of a minus lens, having aspheric surfaces on both surfaces, being concave to the screen side at a central portion including an optical axis; a third lens unit of a plus lens, having spherical surfaces on both surfaces, being convex on both sides; a fourth lens unit of a plus lens, having aspheric surfaces on both surfaces thereof, being curved in concave-like to the screen side, on a peripheral portion far from the optical axis into a radial direction; and a fifth lens unit of a minus lens, being made up with a transparent liquid, commonly serving a faceplate of the CRT projection tube and a cooling, and a meniscus lens, having a thickness being nearly equal to and at least an aspheric surface directing a conc

Abstract: There is disclosed a zoom lens having small variations of aberration and field angle during focusing and having a small system as a whole. The zoom lens includes a first lens unit having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a negative optical power, a fourth lens unit having a positive optical power, and a fifth lens unit having a positive optical power, in order from an object side to an image side. During zooming, the second lens unit and third lens unit are moved, and during focusing, the fifth lens unit is moved. The fifth lens unit consists of one negative lens element and two positive lens elements in order from the object side to the image side, and the following conditions are satisfied: 0<?5<0.35 1.85<?5p/?5n.

Abstract: The zoom lens has, in order from the object to image sides, 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, wherein the second lens unit and the fourth lens unit move during zooming. The following condition is satisfied: ?23<20.0, N23>1.9, ?1.0<f2/f2t<?0.05, where f2 represents a focal length of the second lens unit, ft represents a focal length of the entire system at a telephoto end zoom position, and ?23 and N23 represent an Abbe number and a refractive index of the material forming the third lens of the second lens unit, respectively.

Abstract: Projection exposure device and also projection objective with a lens arrangement which has at least one lens group of negative refractive power, this lens group comprising at least four lenses of negative refractive power, and a lens of positive refractive power being arranged after the third lens of negative refractive power in this lens group.

Abstract: A lens module for a thin scanning device is to be disposed on an optical path from an original to an image sensor, and includes first to fifth lenses and a stop. The first lens has a focal length and a shape factor with identical signs, and is disposed to form an object distance with the original. The second lens has a focal length with a sign opposite to that of the focal length of the first lens, and a shape factor with a sign opposite to that of the shape factor of the first lens. The stop is disposed between the second and third lenses. The third lens has a positive focal length and a positive shape factor. The fourth lens has a positive focal length and a negative shape factor. The fifth lens has a negative focal length and a positive shape factor.

Abstract: A purely refractive projection objective suitable for immersion micro-lithography is designed as a single-waist system with five lens groups, in the case of which a first lens group with a negative refracting power, a second lens group with a positive refracting power, a third lens group with a negative refracting power, a fourth lens group with a positive refracting power and a fifth lens group with a positive refracting power are provided. The system aperture is in the region of maximum beam diameter between the fourth and the fifth lens group. Embodiments of projection objectives according to the invention achieve a very high numerical aperture of NA>1 in conjunction with a large image field, and are distinguished by a good optical correction state and moderate overall size. Pattern widths substantially below 100 nm can be resolved when immersion fluids are used between the projection objective and substrate in the case of operating wavelengths below 200 nm.

Abstract: A projection optical system comprises a first lens group with positive power, a second lens group with negative power, a third lens group with positive power, a fourth lens group with negative power, and a fifth lens group with positive power. At least one of the first, second, and third lens group has an aspherical surface. A lens arrangement of one embodiment has a plurality of waists of lenses, with aspherical surface before and after a first waist.

Abstract: A lens module for a thin scanning device is to be disposed on an optical path from an original to an image sensor, and includes first to fifth lenses and a stop. The first lens has a focal length and a shape factor with identical signs, and is disposed to form an object distance with the original. The second lens has a focal length with a sign opposite to that of the focal length of the first lens, and a shape factor with a sign opposite to that of the shape factor of the first lens. The stop is disposed between the second and third lenses. The third lens has a positive focal length and a positive shape factor. The fourth lens has a positive focal length and a negative shape factor. The fifth lens has a negative focal length and a positive shape factor.

Abstract: The present invention provides a high-performance, thin wide-angle lens suitable for imaging elements with high pixel counts. The wide-angle lens includes, from an object side to an image plane side: a first lens group including a first lens having a negative refractive power and a second lens having a positive refractive power; and a second lens group including a third lens having a negative refractive power, a fourth lens having a positive refractive power, and a fifth lens having a positive refractive power. The fourth lens is bonded to the third lens. The fifth lens is formed with at least one of its convex surfaces being an aspherical surface.

Abstract: An eyepiece lens is constructed with, in order from an entrance side for light to an exit side for light, first, second, third, fourth and fifth lens units of negative, positive, positive, positive and positive refractive powers, respectively. Each of the first, second, third, fourth and fifth lens units of the eyepiece lens is composed only of one lens or a cemented lens, and an intermediate image by an objective lens is formed between the second lens unit and the third lens unit. An objective lens is constructed with, in order from an object side to an image side, first and second lens units of positive and negative refractive powers, respectively. The first and second lens units of the objective lens are composed of one positive lens and of one positive lens and one negative lens, respectively, and the various conditions are appropriately set. An optical apparatus includes the eyepiece lens, the objective lens and an erecting prism.

Abstract: Disclosed is a lens system which includes a first lens of negative optical power having a meniscus shape whose convex surface faces a front, a second lens of positive optical power forming a biconvex shape, an aperture stop, a third lens of negative optical power forming a biconcave shape, a fourth lens of positive optical power, and a fifth lens of positive optical power forming a biconvex shape, which are disposed in order from the front to a rear. Lens intervals, materials composing the lenses, and the like are specified, thereby obtaining a lens system in which a sufficient back focal distance is kept, and which is small in size, low in cost, and satisfactory in optical performance.

Abstract: A lens assembly, which is mounted on a digital still camera (DSC), comprises a fixed aperture, and a lens unit. The lens unit has a first lens, a second lens, a third lens, a fourth lens and a fifth lens in sequence. The first lens is a biconcave lens disposed at the front side of the lens unit. The second lens is a biconvex lens. The third lens is a biconcave lens. The fourth lens is a positive meniscus lens. The fifth lens is a positive lens. The aperture is arranged between the first lens and the second lens.