Abstract: An optical system includes in order from an object side, a negative lens having a concave surface directed toward an object side, an aperture stop, a double convex lens, a negative meniscus lens having a convex surface directed toward an image side, and a positive lens. A surface at the object side of the fourth positive lens is constituted with an aspherical surface, a radius of curvature which decreases from a center portion toward a circumferential portion and a surface at the image side of the positive lens an aspherical surface, radius of curvature of which increases from the center portion toward the circumferential portion and the following condition is satisfied: 0.05<?m/?p<0.80 where m represents the power of the positive lens at the position of the maximum light height and p represents the power of the positive lens at the position the praxis.

Abstract: A lens that can be used in a digital camera includes in sequence a first lens element (20), a second lens element (30), a third lens element (40), and a fourth lens element (50). The first lens element is biconvex, and includes a first aspheric surface (22) and a second aspheric surface (24). The second lens is biconcave, and includes a third aspheric surface (32) and a fourth aspheric surface (34). The third lens element is concavo-convex, and includes a fifth aspheric surface (42) and a sixth aspheric surface (44). The fourth lens element includes a seventh aspheric surface (52) and a eighth aspheric surface (54), the seventh aspheric surface and the eighth aspheric surface being wavelike. All of the lens elements are made from plastic. The lens is light, has strong impact resistance, and provides good image quality.

Abstract: A zoom lens includes a plurality of lens groups including a first lens group arranged on the foremost side and having negative optical power. Zooming is performed by moving at least one of the plurality of lens groups along a direction parallel to an optical axis of the zoom lens. The first lens group is fixed during the zooming. A first lens arranged on the foremost side, of the first lens group has negative refractive power. When an Abbe constant and a partial dispersion of a material configuring the first lens are respectively represented by ?dn and ?g,Fn, a focal distance of the first lens group is represented by f1, and an air-equivalent back focus upon focusing on an infinity object is represented by bf, the following conditions are satisfied: ?dn<32, 0.008<?g,Fn?(0.644?0.00168×?dn)<0.040, and |f1/bf|<0.9.

Abstract: A taking lens apparatus has a zoom lens system that is composed of a plurality of lens units and that achieves zooming by varying the distances between the lens units and an image sensor that converts the optical image formed by the zoom lens system into an electrical signal.

Abstract: A zoom lens system that has a structure suitable to widen a field angle and realizes high optical performance over the entire zoom range is provided. The zoom lens system includes, in order from an object side to an image side, a first lens unit having negative optical power, a second lens unit having positive optical power, a third lens unit having negative optical power, and a fourth lens unit having positive optical power. During zooming from a wide-angle end to a telephoto end, an axial interval between the first lens unit and the second lens unit reduces, an axial interval between the second lens unit and the third lens unit increases, and an axial interval between the third lens unit and the fourth lens unit reduces. In the zoom lens system, a back focus and refractive indices of the respective lens units are suitably set.

Abstract: A zoom lens system in which reductions in the number of lenses and entire lens length are realized is provided. The zoom lens system includes, in order from an object side to an image side, a first lens unit having negative optical power, a second lens unit having positive optical power, and a third lens unit having positive optical power. During zooming from a wide-angle end to a telephoto end, an interval between the first lens unit and the second lens unit reduces and an interval between the second lens unit and the third lens unit changes. An aspherical lens is used for a positive lens element of the first lens unit. Shapes of respective lens elements composing the first lens unit, an interval therebetween, and the like are suitably set.

Abstract: This application discloses a lens system comprising in order from an object side to an image side: an aperture stop; a first lens element, having a positive optical power; and a second lens element, having a negative optical power. By setting the shapes of the respective lens elements and the materials making up the respective lens elements so as to meet predetermined conditions in such a lens system, a lens system of a compact size which provides good optical performance is realized while securing telecentric characteristics.

Abstract: A six element fisheye objective lens comprising a first lens element having a convex object surface facing the object and a concave image surface facing the image plane, a second lens element having a convex object surface facing the object and a concave image facing the image plan. A third lens element has a positive power. A positively powered lens group has a positively powered cemented doublet lens pair. A singlet lens element has a positive power, The lens group has an object surface facing the object and an image surface facing the image. The ratio of the total track to the focal length satisfies the condition that 8<TT/fo<15. The fisheye objective lens has an optical axis, the first, second, third and the lens group being coaxially aligned on the optical axis.

Abstract: A pickup lens is provided in which various aberrations are satisfactorily corrected, which can be manufactured at low cost, and which has an optical length of 10 mm or less. This pickup lens is configured by arranging, in order from the object side, a first lens L1 with a meniscus shape with concave surface on the object side and having negative refractive power, an aperture diaphragm S, a second lens L2 with convex surfaces on both sides and having positive refractive power, a third lens L3 with concave surfaces on both sides and having negative refractive power, and a fourth lens L4 with convex surfaces on both sides and having positive refractive power; and with the following conditions satisfied. +5.0<(r2+r1)/(r2?r1)<+7.0??(1) 0.15f<d1<0.

Abstract: A zoom lens, having a camera shake correction function, that is capable of preventing degradation of chromatic aberration while correcting camera shake, and can be small, light-weight and power-saving, is provided. The zoom lens is composed of four groups of lenses having positive, negative, positive and positive refractive powers, arranged in that order from an object side to an image plane side, where a second lens group conducts zooming and a fourth lens group conducts focus adjustment. The second lens group is made of a concave meniscus lens, a concave lens, a double convex lens, and a concave lens, arranged in that order from the object side to the image plane side, and it includes also at least one aspheric surface. A third lens group includes a cemented lens having a cemented surface whose convex surface faces the object side, and can be shifted in a perpendicular direction with respect to an optical axis in order to correct image fluctuations during a camera shake.

Abstract: An image scanning lens includes four lens components that may include five lens elements as follows: a first lens element having negative refractive power and a meniscus shape with its convex surface on the object side, a second lens element having positive refractive power and a meniscus shape with its convex surface on the object side, a stop, a third biconcave lens element cemented to a fourth biconvex lens element, and a fifth lens element having negative refractive power and a meniscus shape with its concave surface on the object side. The image scanning lens satisfies certain conditions related to the focal lengths of the first, second, and third lens components of the image scanning lens and to the anomalous dispersion of the second lens element. An image scanning device, such as an image scanner, with an image pickup device, such as a CCD, uses the image scanning lens.

Abstract: According to one exemplary embodiment, a projection lens having an object plane and an image plane is provided and includes the following lens groups listed objectwise to imagewise: (1) a first lens group having negative refractive power; and (2) at least three other lens groups having a positive refractive power and at least one other lens group having a negative refractive power. In one embodiment, the projections lens includes a second lens group having a positive refractive power; a third lens group having a negative refractive power; and fourth, fifth and sixth lens groups having overall positive refractive power. The projection lens having a numerical aperture of at least about 0.85 and is of a 1½ waist construction, with the ½ waist defined in the first lens group and a primary waist is defined in the third lens group.

Abstract: A fixed focal length, wide-angle lens includes, in order from the object side, a negative first lens group that includes a plastic negative lens element, a positive second lens group that includes a plastic positive lens element, a positive third lens group that includes a positive lens element joined on its image side to another lens element, and a positive fourth lens group. In the preferred embodiments, all lens groups except the third lens group are single lens elements that each include an aspheric lens surface. Also, the wide-angle lens preferably satisfies specified conditions that, together with the use of plastic lenses, joined lens elements, and aspheric surfaces, enables a high performance, compact, wide-angle lens of relatively simple construction to be produced.

Abstract: A zoom lens system comprises a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having positive refractive power. The first lens group includes a first lens unit having negative refractive power, which includes a negative lens and a negative lens having at least one aspherical surface, and a second lens unit including a positive lens. The second lens group includes an aperture element, a first lens unit having positive refractive power, which has a positive lens, a second lens unit having positive refractive power, which has a cemented positive lens including a positive lens and a negative lens, and a third lens unit having negative refractive power, which has a negative lens having at least one aspherical surface. The third lens group includes a positive lens plating with a multi-layer coating in the surface facing to the object side in order to cut off infrared rays and decrease the influence of infrared rays on image.

Abstract: A compact optical system includes a reduced number of lens elements with a bendable optical path and so is compatible with miniature image pickup devices. The image pickup lens includes, in order from its object side, a first lens element having a negative refracting power, a second lens element having positive refracting power, a stop, a third lens element having a negative refractive power and a fourth lens element having positive refracting power, and satisfies the following conditions (1) and (2) 50>&ngr;d1−&ngr;d2>10  (1) 2>f/f3>0.35  (2) where &ngr;d1 is the d-line reference Abbe number of the first lens element, &ngr;d2 is the d-line reference Abbe number of the second lens element, f is the focal length of the image pickup lens, and f3 is the composite focal length of the third and fourth lens elements. Between the first and the second lens element there is interposed a reflecting surface.

Abstract: A single focus lens is composed of four lens components of negative, positive, negative and positive refractive power, respectively, in order from the object side. The first lens, in order from the object side, has a concave surface on the image side, and a stop is positioned between the first lens and the second lens. The second lens has a convex surface on the object side, the third lens has a concave surface on the object side, and the fourth lens has a convex, aspherical surface on the image side such that the refractive power of the fourth lens becomes weaker towards the edge of the lens. Specified conditions are preferably satisfied in order to provide favorable correction of aberrations.

Abstract: A pickup lens is provided in which various aberrations are satisfactorily corrected, which can be manufactured at low cost, and which has an optical length of 10 mm or less. This pickup lens is configured by arranging, in order from the object side, a first lens L1 with a meniscus shape with concave surface on the object side and having negative refractive power, an aperture diaphragm S, a second lens L2 with convex surfaces on both sides and having positive refractive power, a third lens L3 with concave surfaces on both sides and having negative refractive power, and a fourth lens L4 with convex surfaces on both sides and having positive refractive power; and with the following conditions satisfied.

Abstract: A wide-angle, single focus lens is disclosed that is formed of four lens elements of negative, positive, negative, and positive refractive power, in sequential order from the object side. The first lens element is concave on its object side, the second lens element has at least one surface that is aspheric, and the fourth lens element is convex on its image side and has at least one surface that is aspheric. Specified conditions are preferably satisfied in order to reduce aberrations and provide a bright image while maintaining a short overall lens length.

Abstract: There are provided A zoom lens system comprising, in order from an object side, a first lens unit of negative refractive power, a second lens unit of positive refractive power, a third lens unit of negative refractive power, and a fourth lens unit of positive refractive power, wherein the zoom lens system zooming from a wide angle end to a telephoto end a separation between each lens units is varied so that conditional expressions D1W>D1T, D2W>D2T, and D3W>D3T are satisfied where DiW is a separation between an i-th lens unit and an (i+1)-th lens unit at a wide-angle end, DiT is a separation between an i-th lens unit and an (i+1)-th lens unit at a telephoto end, wherein a diffraction optical element is included in at least one of lens units.

Abstract: A projection zoom lens includes a first lens group having a negative refracting power, a second lens group having a positive refracting power, a third lens group having a negative refracting power, and a fourth lens group having a positive refracting power, which are arranged in that order from a screen side toward an image plane side along an optical axis. The first and the fourth lens group are kept stationary, and the second and the third lens group are moved along the optical axis to vary power from a limit wide angle power toward a limit telephoto power. The second lens group includes a 2nd-group 1st positive lens, a 2nd-group 1st compound lens formed by joining a 2nd-group 2nd positive lens having a convex surface on the image plane side and a 2nd-group 1st negative lens having a concave surface on the screen side, and a 2nd-group 3rd positive lens arranged in that order from the screen side toward the image plane side.

Abstract: An adaptor lens is provided for attachment between a lens of a camera and a camera body, in order to provide the camera with adaptor lens attached, a smaller effective screen size than the camera without the adaptor lens attached. The adaptor lens is formed of, in order from the object side, a front lens group and a rear lens group. The front lens group is formed of, in sequential order from the object side, a negative lens element and at least one meniscus lens element with its concave surface on the object side. The rear lens group is formed of, in sequential order from the object side, a positive lens element with a convex surface on the object side, and a negative lens element. Various conditions are, preferably, satisfied in order to maintain favorable correction of axial chromatic aberration and lateral color.

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 taking lens system has, from the object side, a front lens unit including a first lens element and a second lens element, an aperture stop, and a rear lens unit including a third positive lens element, a fourth negative lens element, and a fifth positive lens element. In the taking lens system, the following condition is fulfilled: 0.3<F/F345<0.9 where F represents the focal length of the entire taking lens system; and F345 represents the composite focal length of the third to fifth lens elements.

Abstract: A zoom optical system provides a series of lens units designed to allow for zooming with minimal change in aberration resulting from the movement of the lens units. Each lens unit has a plurality of lens units. One embodiment has, in order from the object side, a first lens unit having a negative refractive power, a second lens unit having a positive 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 may have at least one gradient index lens element and the first lens unit is kept stationary during a change of magnification. Additional embodiments have more or fewer lens units and the refractive power of each lens unit is varied. In some embodiments, a lens unit other than the first lens unit is kept stationary.

Abstract: Projection lens systems (13) for use in projection televisions are provided. The systems are characterized by a screen side lens unit (U1) which: (1) has a weak optical power; (2) has a negative, aspherical lens element composed of a high dispersion material; and (3) has a positive lens element which is composed of a low dispersion material.

Abstract: An objective optical system is disclosed having, in a first construction, in relative order from the object side, a first lens element of negative refractive power, a visual field conversion optical element which folds light rays incident thereon, a stop, and either one or two additional lens elements of positive refractive power which form an objective optical system. Certain prescribed conditions are satisfied in order that the objective optical system be compact and have acceptably small aberrations to thereby enable a high quality image to be formed. In a second alternative construction, the stop is positioned after the second lens element and the third lens element includes a convex surface on the image side and satisfies a prescribed condition.

Abstract: An objective lens including first, second, third, and fourth lens units in order from the object side. The first lens unit consists of a first lens of negative refractive power in the shape of a meniscus with a concave surface toward the image field side. The second lens unit consists of a second lens of positive refractive power. The third lens unit consists of a composite lens having joined together a third lens of negative refractive power with a concave surface toward the object side and a fourth lens of positive refractive power with a convex surface toward the image field side, the third lens unit having as a whole negative refractive power. The fourth lens unit consists of a fifth lens of positive refractive power. The objective lens has a predetermined condition for focal length.

Abstract: A zoom lens of the negative lead type includes, in order from the object side, a first lens unit of negative refractive power, a second lens unit of positive refractive power, a third lens unit of negative refractive power consisting of one negative lens, and a fourth lens unit of positive refractive power consisting of one positive lens, wherein, during zooming from the wide-angle end to the telephoto end, all the lens units move along an optical axis in such a manner that the separation between the first lens unit and the second lens unit decreases, the separation between the second lens unit and the third lens unit increases and the separation between the third lens unit and the fourth lens unit decreases.

Abstract: A zoom optical system is disclosed. The zoom optical system provides a series of lens units designed to allow for zooming with minimal change in aberration resulting from the movement of the lens units. To achieve this goal each lens unit is has a plurality of lens units. By way of example, one embodiment of the present invention has, in order from the object side, a first lens unit having a negative refractive power, a second lens unit having a positive 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 comprises at least one gradient index lens element and the first lens unit is kept stationary during a change of magnification. Additional embodiments are described in which more or fewer lens units are used and the refractive power of each lens unit is varied. In some embodiments, a lens unit other than the first lens unit is kept stationary.

Abstract: A projection lens device for extensively projecting an original image being displayed on an image source, such as a liquid crystal panel, upon a screen, comprising in sequence from the screen: a first lens group having a negative refractive power as an entire system thereof, and including at least a meniscus lens of negative refractive power, which has a convex surface toward the screen side; a second lens group having a positive refractive power as an entire system thereof, and including cemented lenses having a negative refractive power, one of which has convex surfaces at both sides and a first Abbe's number and the other of which has concave surfaces at both sides and a second Abbe's number being smaller than the first Abbe's number; and a third lens group having a negative refractive power as an entire system thereof, and including at least a lens which has a concave surface at a center thereof toward the screen.

Abstract: A wide-field eyepiece, formed of at least four lens groups and five lens elements, is disclosed which satisfies predetermined conditional expressions, so as to provide an eyepiece having an angle of view of at least 65 degrees with less than 6% distortion. The wide-field eyepiece is formed of, in order from the side of an image position 1 formed by an objective lens (not illustrated): a first lens group G.sub.1 of negative refractive power that includes a first lens element L.sub.1 having a concave surface on both sides, a second lens group G.sub.2 of positive refractive power that includes a second lens element L.sub.2 having a convex surface on the side of an observer's eye position, a third lens group G.sub.3 of positive refractive power wherein a lens element surface thereof has a convex surface on both sides and is cemented to a negative lens element having a concave surface on the side nearest the image 1 formed by the objective lens; and a fourth lens group G.sub.

Abstract: A high-resolution objective for large-format photography has a pair of positive meniscuses flanking a stop area forming a lens aperture; and a respective negative cemented doublet on a side of each meniscus turned away from the stop area, the positive meniscuses being composed of glass having anomalous partial dispersion, a refractive index n.sub.e <1.63 and a dispersion or Abbe number .nu..sub.e >63, the cemented doublets each having a negative lens element and a positive lens element, the negative lens element being composed of a lead-free, arsenic-free and antimony-free glass with an anomalous dispersion, a refractive index n.sub.e >1.63 and an Abbe number .nu..sub.e <50.

Abstract: A four element, athermalized projection lens for use in forming an enlarged color image of a LCD panel is disclosed. The powers of the elements from the screen to the LCD are negative/positive/negative/positive and the dispersions are low dispersion/low dispersion/high dispersion/low dispersion. The first three elements are composed of plastic and the last element is composed of glass. The projection lens exhibits a high level of aberration correction over magnifications ranging from about 5.times. to about 12.times.. The four element design comprises the minimum number of elements capable of achieving a relatively long back focal length, athermalization, and lateral color correction of less than about half a pixel.

Abstract: In a retro-focus type objective lens for an endoscope, its front-group concave lens system is constituted by two concave lenses, and a predetermined conditional expression is satisfied, so as to secure a sufficient length of back focus, while fully favorably correcting chromatic aberration in magnification. A four group lens configuration having five lenses comprising a front-group concave lens system composed of two concave lenses L.sub.1 and L.sub.2, a rear convex lens system composed of lenses L.sub.3 and L.sub.5, with an aperture stop interposed therebetween, in order to secure a long back focus at least three times the composite focal length of the whole system, satisfied is the following conditional expression:dx.gtoreq.3.0.times..vertline.f.sub.F .vertline. (1)wherein f.sub.

Abstract: An optical system for use in an infrared camera which includes, in order from an object side: a first lens group having a negative refractive power and a second lens group having a positive refractive power arranged a distance from the first lens group. The first lens group comprises a negative meniscus lens having a convex surface facing toward the object side and the second lens group comprising, in order from the object side: a first lens having a positive refractive power, a second lens having a negative refractive power and a third lens having a positive refractive power. The lenses comply with the following conditions: (1) 0.5.PHI.<-.PHI.f<0.7.PHI., (2) 0.55.PHI.<.PHI.r<0.87.PHI., (3) 1.55 (1/.PHI.)<d<1.98 (1/.PHI.) and (4) dr<2.1 (1/.PHI.). The conditions are defined by: .PHI.: is the overall refractive power for the overall optical system for the infrared camera, .PHI.f: is the refractive power for the first lens group, .PHI.

Abstract: A small, light weight wide angle photographic lens has attachment size of less than approximately 3.5 times the focal length and has a field angle of approximately 100.degree..The wide angle photographic lens includes a first lens L.sub.1 having a negative refractive power and a concave surface facing the image side; a second lens L.sub.2 with a positive refractive power having the convex surface facing the object side; a third lens L.sub.3 having a negative refractive power cemented to the second lens L.sub.2 and having a surface with a larger absolute value of index of refraction on the image side; a fourth lens L.sub.4 having a positive refractive power cemented to the third lens L.sub.3 and having a surface with a larger index of refraction on the object side; and a plurality of lenses on the image side of the fourth lens L.sub.4, wherein the concave surface of the first lens L.sub.1 is an aspherical surface with a conical constant .kappa. greater than 0.3 and less than 0.

Abstract: A variable focal length optical system includes, in succession from an object side, a first lens component, a second lens component, a third lens component, and a fourth lens component, wherein at least two air gaps of a first air gap between the first lens component and the second lens component, a second air gap between the second lens component and the third lens component, and a third air gap between the third lens component and the fourth lens component change when the focal length of the zoom lens is changed.

Abstract: A wide angle lens is constituted by four sheets of concave, concave, convex, and convex lenses successively arranged from the object side so as to satisfy predetermined conditional expressions concerning focal lengths, whereby various kinds of aberration are favorably corrected and, while the cost required for molding each lens is minimized, a higher brightness can be obtained as compared with the conventional wide angle lens. From the object side, first, second, third, and fourth lenses (L.sub.1 to L.sub.4) are successively disposed. Each of the first lens (L.sub.1) and second lens (L.sub.2) is made of a negative meniscus lens whose concave surface with a stronger curvature is directed toward the imaging surface (1), while each of the third lens (L.sub.3) and the fourth lens (L.sub.4) is made of a biconvex lens whose surface with a stronger curvature is directed toward the imaging surface (1), such that f.sub.2 /f.sub.1 is 0.888 thereby satisfying a conditional expression of 0.8<f.sub.2 /f.sub.1 <1.

Abstract: An optical system of a projection display apparatus includes a projection lens assembly having a first lens group having a negative power, a second lens group having a negative power and a third lens group having a positive power, all arranged in this order from a side of a screen. An air space is provided between the first and second lens groups and also between the second and third lens groups. Each air space is longer than the entire length of the second lens group as taken along the optical axis of the assembly.

Abstract: An inverse telephoto large aperture wide angle lens comprises a first lens group with a negative refractive power, a second lens group with a positive refractive power, a stop, a third lens group with a negative refractive power, and a fourth lens group with a positive refractive power arranged in the named order from a side of an object, in which for focusing on a near object from infinity the first lens group is fixed with respect to an image surface, and the second, third, and fourth lens groups are moved along an optical axis thereof toward the object such that a space between the first lens group and the second group and a space between the second lens group and the third lens group decrease, but a space between the third lens group and the fourth lens group increases.

Abstract: An imaging lens system is disclosed which comprises a focusing lens and a correcting lens which has aspherical surfaces on both side. Usually, the focusing lens if located on the object side but the correcting lens may be disposed on the object side.