Abstract: The imaging lens consists of, in order from the object side, a first lens group having a positive power, a second lens group having a negative power, and a third lens group. The first lens group consists of, in order from the object side, a positive front group, a stop, and a positive rear group. The rear group has a cemented lens consisting of a negative lens concave toward the image side and a positive lens convex toward the image side in order from the object side. The second lens group consists of a negative lens. During focusing, only the second lens group moves. The following conditional expression relating to a focal length f2 of the second lens group and focal length f of the whole system is satisfied: 0.8<|f2/f|<5.

Abstract: An imaging lens substantially consists of a negative first lens group and a positive second lens group in this order from the object side. The first lens group substantially consists of only a first lens, which is one biconcave lens. The second lens group substantially consists of, in the following order from the object side: a cemented lens, which is formed by bonding a second lens, i.e., a biconvex lens, and a third lens, i.e., a negative meniscus lens, in this order from the object side, and which has a positive refractive power as a whole; an aperture stop; and a cemented lens that is formed by bonding a fourth lens, i.e., a biconvex lens and a fifth lens, i.e., a negative meniscus lens in this order from the object side and that has a positive refractive power as a whole.

Abstract: An optical system includes, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, and a third lens group having positive refractive power. The second lens group is moved upon carrying out focusing from an infinitely distant object to a close object, at least a portion of the third lens group is moved in a direction including a component perpendicular to an optical axis, and given conditional expressions is satisfied. Accordingly, an optical system excellently suppressing variations in aberrations generated upon vibration reduction, an optical apparatus equipped therewith, and a method for manufacturing the optical system are provided.

Abstract: A fixed focus lens comprising, sequentially from an object side, a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a positive refractive power. The first lens group includes an aperture stop. The second lens group is configured by a single lens element. During focusing, the second lens group moves along an optical axis and the first lens group and the third lens group are fixed with respect to an imaging plane.

Abstract: Provided is an imaging lens including a fixed first lens group having a positive refractive power and including a plurality of lenses, a second lens group serving as a focus group and including a negative lens, and a third lens group having a positive refractive power that are arranged sequentially from an object side to an image side. A stop is disposed between predetermined lenses of the first lens group, and, on an assumption that a lens group located closer to the object side than the stop of the first lens group is a 1ath lens group and a lens group located closer to the image side than the stop is a 1bth lens group, Condition Equation (1) below is satisfied: 0.7<f/f1b<2.0,??(1) where f is a focal distance of an entire system and f1b is a focal distance of the 1bth lens group.

Abstract: An imaging optical system includes, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, an aperture stop, and a third lens unit having a positive refractive power. The second lens unit moves toward the image side during focusing from a far object to a near object. The third lens unit includes, in order from the object side to the image side, two lenses having concave surfaces that face each other with a largest air gap in the third lens unit provided therebetween, and a positive lens. A focal length of the entire imaging optical system and a focal length of the second lens unit are appropriately set.

Abstract: A photographic optical system includes, in order from an object side to an image side, a first lens unit, a second lens unit for focusing, and a third lens unit. The first lens unit includes a first lens sub-unit having a positive refractive power and a second lens sub-unit. The first lens unit includes a diffractive optical element and an aspheric surface. A length on an optical axis from a lens surface furthest on the object side of the first lens sub-unit to an image plane, an air space between the first lens sub-unit and the second lens sub-unit, a focal length of the first lens sub-unit, a focal length of the second lens sub-unit, a focal length of the diffractive optical element by only a diffractive component, a focal length and an F-number of the entire photographic optical system are appropriately set to satisfy predetermined conditions for optimal focusing.

Abstract: An internal focus lens comprising sequentially from an object side a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a positive refractive power. The second lens group is configured by a simple lens element and is moved along an optical axis to perform focusing. The internal focus lens satisfies condition expressions (1) 0.48<|f3|/f<0.73 and (2) 1.05<Fno×f1/f<1.42, where f3 is the focal length of the third lens group, f is the focal length of the entire optical system, f1 is the focal length of the first lens group, and Fno is the F number of the entire optical system.

Abstract: Provided is an imaging lens including a fixed first lens group having a positive refractive power and including a plurality of lenses, a second lens group serving as a focus group and including a negative lens, and a third lens group having a positive refractive power that are arranged sequentially from an object side to an image side. A stop is disposed between predetermined lenses of the first lens group, and, on an assumption that a lens group located closer to the object side than the stop of the first lens group is a 1ath lens group and a lens group located closer to the image side than the stop is a 1bth lens group, Condition Equation (1) below is satisfied: 0.7<f/f1b<2.0,??(1) where f is a focal distance of an entire system and f1b is a focal distance of the 1bth lens group.

Abstract: An internal focus lens comprising sequentially from an object side a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a positive refractive power. The second lens group is configured by a simple lens element and is moved along an optical axis to perform focusing. The internal focus lens satisfies condition expressions (1) 0.48<|f3|/f<0.73 and (2) 1.05<Fno×f1/f<1.42, where f3 is the focal length of the third lens group, f is the focal length of the entire optical system, f1 is the focal length of the first lens group, and Fno is the F number of the entire optical system.

Abstract: An internal focusing lens includes sequentially from an object side, a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a positive refractive power. During focusing, the second lens group is moved along the optical axis and, the first lens group and the third lens group are fixed. The internal focusing lens satisfies a conditional expression (1) 0.31<f1/f<0.58, where f1 is the focal length of the first lens group and f is the focal length of the entire optical system, at infinity focus.

Abstract: Embodiments of an optical zoom lens system may comprise three lens groups with a PNP power sequence. The first lens group may vary focus. The second and third lens groups may be movable to vary magnification during zoom. The first lens group may include three lens subgroups with an NNP power sequence: a stationary first lens subgroup, a second lens subgroup including a movable lens element, and a stationary or movable third lens subgroup. The second lens subgroup may include two parts, which may be movable at different rates of travel to vary focus. One part may include the movable lens element. Lens elements of the first lens group may be movable according to different focus movement plans. In the first lens group, lens element movement and lens element power may contribute to provide low focus breathing over the entire zoom range. The F-number may be F/2.8 or less.

Abstract: A lens module includes a first lens group with a positive refractive power, a second lens group with a negative refractive power, and a third lens group with a positive refractive power. The first lens group essentially consists of a first lens with a negative refractive power, a second lens with a positive refractive power and a third lens with a positive refractive power arranged in order from a magnified side to a reduced side. The second lens group essentially consists of a fourth lens with a negative refractive power and a fifth lens with a positive refractive power arranged in order from the magnified side to the reduced side. The third lens group essentially consists of a sixth lens with a positive refractive power and a seventh lens with a positive refractive power arranged in order from the magnified side to the reduced side.

Abstract: A projection lens is composed of a positive first lens group, a negative second lens group, and a positive third lens group, which are sequentially arranged from the magnification side of the projection lens, and the reduction side of the projection lens is telecentric. Further, the following formulas (1) and (2) are satisfied: 0.30?d23/f3?0.65??(1); and 10?|D12/ff|??(2), where d23: space in air between the second lens group and the third lens group, f3: focal length of the third lens group, D12: total length of the first lens group and the second lens group in the direction of an optical axis, and ff: length from the most magnification-side surface in the entire system of the projection lens to a magnification-side focus position of the entire system.

Abstract: Provided is an imaging lens, including, in order from an object side: a positive first lens; a second lens having a concave shape toward the object side; and (i?2) number of lens, wherein the i-th lens, which is the most image-side lens, includes: an i-th lens flat plate; and a positive or negative lens element on at least one of the opposite surfaces of the i-th lens flat plate, wherein the following conditional relationship is satisfied: 0.9>Ymax/Y>0.61, where: Ymax is a height of the most off-axial ray on an image-side surface of the (i?1)th lens; and Y is a maximum image height.

Abstract: An imaging lens includes a first lens group that includes sequentially from an object side, a first lens formed of resin and having a positive refractive power and a second lens formed of resin and having a negative refractive power, the first lens and the second lens collectively forming a cemented lens having a positive refractive power. The imaging lens further includes a second lens group that includes a negative lens having a convex surface directed toward an image plane and a third lens group that includes a positive lens, where the first lens group, the second lens group, and the third lens groups are sequentially arranged from the object side.

Abstract: Methods and apparatus to correct a curved Petzval focusing surface to a plane using a convex lens, a concave lens, and a space arranged between the curved side of the convex lens and the curved side of the concave lens. The method and apparatus may also include a Fresnel lens arranged between the concave lens and a pixel array.

Abstract: A lens system with a first group having a positive meniscus lens and a sensor. The optical distance between the front surface of the first group and the sensor can be not greater than the height of the sensor times the image F-number, which may alternatively be referred to as the working F-number. A second group can be disposed adjacent to the front focal point of the first group, and a lens-stop can be disposed adjacent to the second group. A third group can be disposed midway between the lens-stop and the object field of the first and second groups. The image F-number can be 2.8 or greater. The first group can have a doublet formed by a first lens that is plano convex and a second lens that is plano concave. The second group can have a first, plano convex lens and a second, biconvex lens forming a doublet with a third, plano concave lens.

Abstract: A wide-angle zoom optic system includes: in an order from an object, a first lens group having a negative refractive power; a second lens group having a positive refractive power; and a third lens group having a positive refractive power, wherein the first lens group includes two lens elements. In the zoom optic system, the ratio of the distance between the last lens element with respect to the object and an image field at a wide-angle position to a focal length at the wide-angle position is adjusted, so that a compact zoom optic system having a high magnification and a wide viewing angle can be implemented.

Abstract: An imaging lens includes a first lens group that includes sequentially from an object side, a first lens formed of resin and having a positive refractive power and a second lens formed of resin and having a negative refractive power, the first lens and the second lens collectively forming a cemented lens having a positive refractive power. The imaging lens further includes a second lens group that includes a negative lens having a convex surface directed toward an image plane and a third lens group that includes a positive lens, where the first lens group, the second lens group, and the third lens groups are sequentially arranged from the object side.

Abstract: Provided is an optical system in which chromatic aberrations can be excellently corrected in spite of environmental changes, to thereby maintain high optical performance. The optical system includes: a plurality of optical elements each having refractive surfaces located in a light incident side and a light exit side; and an aperture stop. A focal length, an Abbe number of a material, and an extraordinary partial dispersion ratio of each of an l-th optical element and an r-th optical element which satisfy a condition related to the extraordinary partial dispersion ratio are suitably set.

Abstract: Disclosed is a high-definition imaging lens assembly that can reduce the length of an optical path. The high-definition imaging lens assembly includes: first, second, third, and fourth lenses that are sequentially disposed from an object along an optical axis, wherein the first lens has positive refractive power and the second lens has negative refractive power, the first and second lenses are made of optical glass, a front surface of the first lens and a rear surface of the second lens are spherical, and a rear surface of the first lens and a front surface of the second lens that are substantially planar are bonded to each other. The third and fourth lenses are made of plastic and are spaced each other and at least one surface of each of the third and fourth lenses is aspherical.

Abstract: An optical system includes at least one of a movable lens unit movable in an optical axis direction and a fixed lens unit that is not movable in the optical axis direction. The at least one lens unit includes a plurality of refractive optical elements. The refractive optical elements are made of resin and have focal lengths of the same sign. When ?i is a refractive power, with respect to d-line, of the ith refractive optical element from an object side, ?G is a refractive power of a negative lens in the lens unit including the refractive optical elements, and ?a is an average refractive power, with respect to d-line, of the refractive optical elements, ?i, ?G, and ?a are adequately set.

Abstract: The purpose is to provide a large-aperture-ratio internal focusing telephoto lens applicable to a wider photographing area by equipping a vibration reduction function capable to satisfactorily correct a camera shake and the like with securing superb optical performance. The large-aperture-ratio internal focusing telephoto lens includes, in order from an object, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. The second lens group G2 is moved along an optical axis upon changing focus from infinity to a close-range object. The first lens group G1 has at least two cemented lenses and satisfies a given conditional expression. Either one of the cemented lens satisfies a given conditional expression.

Abstract: A compact and light-weighted projection lens system that is capable of projecting an image at an angle as wide as 75 degrees with sufficient field angle and brightness as represented by F number of approximately 2.4, that is capable of effectively correcting chroic aberration of magnification and aberration of distortion and exhibiting optical stability against environmental variations, and that is suitable for obtaining an extraordinarily fine image by the magnification and projection.

Abstract: The present invention provides a compact, thin zoom lens. The zoom lens according to the present invention includes, from an object side to an image plane side, a first lens group having an overall negative overall refractive power, a second lens group having an overall positive refractive power; and a third lens group having an overall positive refractive power. The first lens group includes a first lens and a second lens bonded together and having a negative refractive power. The second lens group includes a third lens with a positive refractive power, and a fourth lens and a fifth lens bonded together and having a negative refractive power. The third lens group includes a sixth lens having a positive refractive power. As a result, the total length is reduced, the retracted length can be reduced, and the zoom lens can be compact and thin.

Abstract: An image stabilizing optical lens device including, in order from an object side to an image side of the image stabilizing optical lens device, a first lens unit having positive refractive power, a second lens unit having negative refractive power and being movable along an optical axis of the image stabilizing optical lens device to perform focusing, and a third lens unit having positive refractive power, the third lens unit including a front lens sub-unit having negative refractive power and being movable so as to be decentered with respect to the optical axis and a rear lens sub-unit having positive refractive power.

Abstract: This invention is related to a compact photographing lens wherein an aperture stop is arranged at a position closest to an object, a first lens group, a second lens group, and a third lens group are arranged sequentially from the object side, the first lens group is formed by arranging, sequentially from the object side, a first lens having a positive refracting power and a second lens having a negative refracting power and bonded to the first lens, the second lens being formed from a meniscus lens with a concave surface facing the object side, the second lens group is formed from only a third lens as a meniscus lens which has at least one aspherical refracting surface and a concave surface facing the object side, the third lens group is formed from only a fourth lens as a meniscus lens which has at least one aspherical refracting surface and a convex surface facing the object side.

Abstract: In a zoom lens comprising first to fourth lens groups, the second lens group comprises two meniscus lenses and an achromatic lens. The achromatic lens comprises a cemented lens having a negative refracting power as a whole, and a lens having a positive refracting power with a convex surface directed onto the object side. The cemented lens comprises a meniscus lens or plane-convex lens having a positive refracting power with a concave surface or plane directed onto the object side, and a lens having a negative refracting power.

Abstract: An image stabilizing optical lens device including, in order from an object side to an image side of the image stabilizing optical lens device, a first lens unit having positive refractive power, a second lens unit having negative refractive power and being movable along an optical axis of the image stabilizing optical lens device to perform focusing, and a third lens unit having positive refractive power, the third lens unit including a front lens sub-unit having negative refractive power and being movable so as to be decentered with respect to the optical axis and a rear lens sub-unit having positive refractive power.

Abstract: A retrofocus lens system has a negative first, a positive second and a positive third lens group. The first lens group includes an aspheric first lens, a negative meniscus second and third lenses that are convex on the large conjugate side, and a negative meniscus fourth lens being convex on the small conjugate side. The second lens group includes a positive fifth lens and a sixth lens joined to the fifth lens. The third lens group includes a positive meniscus seventh lens being convex on the small conjugate side, a biconcave eighth lens, a positive ninth lens joined to the eighth lens, a biconvex tenth and eleventh lenses, and an aspheric twelfth lens. The system satisfies 0.8<f2/f3<1.5, 1.6<|f1|/f<2.

Abstract: An objective optical system comprising, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power and a third lens unit having a positive refractive power, wherein the second lens unit is moved along an optical axis for changing a magnification. This objective optical system is configured to be compact and have favorable optical performance by adequately selecting an airspace between the first lens unit and the second lens unit as well as a power for the first lens unit.

Abstract: A standard lens system composed, in order from the object side, of a first lens unit having a positive refractive power, an aperture stop, a second lens unit having a positive refractive power and a third lens unit having a negative refractive power: the first lens unit being composed of at least one positive meniscus lens component which has a convex surface on the object side, and at least one doublet which consists of a positive meniscus lens component and a negative lens component; the second lens unit being composed of at least one cemented doublet which consists of a negative lens element and a positive lens element, and a positive lens component; and the third lens unit being composed of at least one positive lens component and a negative lens component or at least one negative lens component.

Abstract: An achromatic lens system includes in order, from the object side, a front lens group, a chromatic aberration correcting lens group, and a rear lens group. Aberrations, including spherical aberration, coma, astigmatism, curvature of image, as well as axial chromatic aberration of wavelengths from green to red, are substantially corrected by the front lens group and the rear lens group. The axial chromatic aberration of the wavelength blue, caused by the front lens group and the rear lens group, is corrected by the chromatic aberration correcting lens group.

Abstract: A Fourier transform lens assembly suited for use in an optical information processor includes a first lens group having a positive power, a second lens group having a negative power disposed on one side of the first lens group, and a third lens group having a positive power disposed on the side opposite to the first lens group with respect to the second lens group. The distance between a front focal plane and a back focal plane of the Fourier transform lens assembly is less than two times a focal length of the Fourier transform lens assembly.

Abstract: A new and improved projector lens arrangement which can automatically adjusted for focusing purposes in an easily and convenient manner according to a novel focusing method of the present invention. The projection lens arrangement generally includes three groups of optical elements aligned along a common optical axis with a variable vertex length and wide field coverage angle. One element group near the object is a doublet having a negative element with a concave surface and a positive element being bi-convex having one surface near the image complementarily shaped to the concave surface of the negative element.

Abstract: Binoculars designed to provide a large aided static field of view are provided. The binoculars are characterized by S/D ratios of above 2.8, where S is the binoculars' aided static field of view calculated by multiplying the binoculars' magnifying power by the binoculars' semi field of view in object space and D is given by tan.sup.-1 [(R.sub.ex +1.5)/13], where R.sub.ex is the radius of the binoculars' exit pupil and where R.sub.ex and the constants 1.5 and 13 are measured in millimeters. As a result of the increased S/D ratio, the binoculars of the invention minimize the sensation of tunnel vision which normally occurs when binoculars are used and reduce the user's apprehension of missing activities in his or her peripheral vision. In certain embodiments, a movable field lens unit is employed to provide variable power and a negative corrector lens unit is employed for aberration correction and to minimize the size of the binoculars. The binoculars are suitable for mass production and general consumer use.

Abstract: An objective for use in photographic compact cameras has a relative aperture of 3.5 and a focal length of 35 mm, and is of the triplet type. The lens element on the object side is a cemented element. In order to achieve an extremely compact structural shape and balanced monochromatic correction, as well as a reduction in the chromatic magnification difference, the color coma and the color astigmatism, four design conditions are specified.

Abstract: A zoom lens for the projector includes, in order from a screen, a first lens unit of positive refractive power, a second lens unit of negative refractive power and a third lens unit of positive refractive power, zooming from the wide-angle end to the telephoto end being performed by axially moving the second and third lens units in such a manner that the air separation between the first and second lens unit increases, while the air separation between the second and third lens units decreases, and the following conditions being satisfied:1<-.beta.3w<1.50.8<-.beta.2w<1.20.25<-f2/fw<0.450.7<e2w/fw<1.1where .beta.2w and .beta.3w are the image magnifications for an infinitely distant object of the second and third lens units in the wide-angle end, respectively, f2 is the focal length of the second lens unit, e2w is the interval between the principal points of the second and third lens units, and fw is the shortest focal length of the entire lens system.

Abstract: A zoom lens comprises a first lens unit having a positive refractive power, a second lens group having a negative refractive power, an iris and a third lens unit having a positive refractive power, arranged in this sequence as viewed from an object. The third lens unit comprises a lens unit 3a and a lens unit 3b arranged in this sequence as viewed from the object, with a large air gap therebetween. Zooming from a short focal length end to a long focal length end is effected by moving the second lens group from a unit side to a image side and moving the first lens unit and the third lens unit to depict convex loci toward the object. The zoom lens meets the condition of-0.3<HF.sub.3 /f.sub.3 <0.20.5<l.sub.3 /f.sub.3 <1.5whereHF.sub.3 is a distance between an apex of a lens of the third lens group facing the object and a front principal point of the third lens unit,f.sub.3 is a focal length of the third lens unit, andl.sub.3 is an air gap between the lens unit 3a and the lens unit 3b.

Abstract: A method is described for selecting optical materials to use in designing color-corrected optical systems. Various dioptric, catadioptric and anamorphic optical systems are described, which use only two different types of optical materials to obtain precise axial color correction at three, four or five wavelengths (depending upon the particular optical materials), with only very small chromatic aberration occurring at wavelengths between the precisely color-corrected wavelengths. Examples of color-corrected lens systems comprising more than two glasses are also described.

Abstract: The invention relates to an eyepiece that has an improved image surface flatness even at a wider field angle, is well corrected for various aberrations inclusive chromatic aberration of pupil and is usable with inexpensive microscopes (esp., stereoscopic ones). The eyepiece of the invention is an eyepiece including at least three lens components comprising a cemented lens component consisting positive and negative lens elements and a lens component having a negative refractive power in its entirety, characterized in that the lens component other than the lens components proximate to the object and eye sides is provided with a plastic lens element or elements having at least one aspherical surface.