Abstract: An imaging lens system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens sequentially disposed from an object side. The system satisfies TTL/f<1.0 and D23/D34<1.2, where TTL is a distance from an object-side surface of the first lens to an imaging plane, f is a focal length of the imaging lens system, D23 is a distance from an image-side surface of the second lens to an object-side surface of the third lens, and D34 is a distance from an image-side surface of the third lens to an object-side surface of the fourth lens.

Abstract: The present disclosure discloses an optical imaging lens assembly including, sequentially from an object side to an image side along an optical axis, a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens. Each of the first to the sixth lenses has reactive power. The second lens has positive refractive power. An image-side surface of the fourth lens is concave. A radius of curvature R2 of an image-side surface of the first lens, a radius of curvature R5 of an object-side surface of the third lens and an effective focal length f3 of the third lens satisfy: 2.5<(R2+R5)/f3<11.0.

Abstract: There is provided an imaging lens with excellent optical characteristics which satisfies demand of a low profile and a low F-number. An imaging lens comprises in order from an object side to an image side, a first lens with positive refractive power being formed in a meniscus shape having an object-side surface being convex in a paraxial region, a second lens with positive refractive power in a paraxial region, a third lens with negative refractive power in a paraxial region, a fourth lens with positive refractive power in a paraxial region, a fifth lens having aspheric surfaces on both sides, and a sixth lens with negative refractive power having an image-side surface being concave in a paraxial region, and predetermined conditional expressions are satisfied.

Abstract: There is provided an imaging lens with excellent optical characteristics which satisfies demand of a low profile and a low F-number. An imaging lens comprises in order from an object side to an image side, a first lens with positive refractive power being formed in a meniscus shape having an object-side surface being convex in a paraxial region, a second lens with positive refractive power in a paraxial region, a third lens with negative refractive power in a paraxial region, a fourth lens with positive refractive power in a paraxial region, a fifth lens having aspheric surfaces on both sides, and a sixth lens with negative refractive power having an image-side surface being concave in a paraxial region, and predetermined conditional expressions are satisfied.

Abstract: There is provided a compact imaging lens which meets demand of low-profileness, reduction in telephoto ratio and low F-number, and properly corrects aberrations. An imaging lens comprising in order from an object side to an image side, a first lens, a second lens, a third lens, a fourth lens having a convex surface facing the image side near an optical axis, and a fifth lens having positive refractive power, wherein a below conditional expression (1) is satisfied: 0.64<TTL/f<1.0??(1) where f: focal length of the overall optical system of the imaging lens, and TTL: distance along the optical axis from an object-side surface of the first lens to an image plane.

Abstract: A lens module includes lenses sequentially arranged from an object side toward an image plane sensor and having respective refractive powers. A second lens of the lenses has a convex object-side surface and a convex image-side surface. A first lens and a third lens of the lenses are symmetrical to each other in relation to the second lens.

Abstract: The present disclosure relates to optical lens, in particular to a camera optical lens, comprising, from an object side to an image side in sequence: a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens; the second lens has a negative refractive power, and the third lens has a negative refractive power; wherein the camera optical lens satisfies the following conditions: 2.00?f1/f?3.00, ?20.00?R5/d5??10.00; where, f denotes a focus length of the camera optical lens, f1 denotes a focus length of the first lens, R5 denotes a curvature radius of an object side surface of the third lens, and d5 denotes an on-axis thickness of the third lens. The camera optical lens has a high performance and satisfies a design requirement of low TTL.

Abstract: The present disclosure relates to the technical field of optical lens and discloses a camera optical lens. The camera optical lens includes, from an object side to an image side: a first lens, a second lens having a positive refractive power, a third lens having a negative refractive power, a fourth lens, a fifth lens and a sixth lens. The camera optical lens satisfies the following conditions: 4.00?f1/f?10.00 and ?40.00?R5/d5??20.00, where f denotes a focal length of the camera optical lens; f1 denotes a focal length of the first lens; R5 denotes a curvature radius of an object-side surface of the third lens; d5 denotes an on-axis thickness of the third lens. The camera optical lens can achieve a high imaging performance while obtaining a low TTL.

Abstract: The present disclosure relates to an optical lens, in particular to a camera optical lens. The camera optical lens includes, from an object side to an image side in sequence: a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, the first lens has a positive refractive power, the second lens has a positive refractive power, and the third lens has a negative refractive power, and the camera optical lens satisfies the following conditions: ?20.00?f2/f3??10.00, and 0.50?d1/d3?3.00, where f2 denotes a focal length of the second lens, f3 denotes a focal length of the third lens, d1 denotes an on-axis thickness of the first lens, and d3 denotes an on-axis thickness of the second lens. The camera optical lens can obtain high imaging performance and a low TTL.

Abstract: The present disclosure relates to the technical field of optical lens and discloses a camera optical lens. The camera optical lens includes, from an object side to an image side: a first lens, a second lens having a positive refractive power, a third lens having a negative refractive power, a fourth lens, a fifth lens and a sixth lens. The camera optical lens satisfies following conditions: 4.02?f1/f?7.01; and 32.00?R5/d5?42.00; f denotes a focal length of the camera optical lens; f1 denotes a focal length of the first lens; R5 denotes a curvature radius of an object-side surface of the third lens; and d5 denotes an on-axis thickness of the third lens. The camera optical lens can achieve a high imaging performance while obtaining a low TTL.

Abstract: An optical imaging system is described including first to sixth lenses sequentially disposed from an object side to an image side, and an image sensor configured to convert incident light reflected from a subject, having passed through the first to sixth lenses, into an electrical signal. One of the first to sixth lenses includes a spherical object-side surface and another of the first to sixth lenses includes corresponding aspherical object-side surfaces. The first to sixth lenses include corresponding aspherical image-side surfaces, and a lens of the first to sixth lenses that is closer to the object side than the one of the first to sixth lenses including the spherical object-side surface, has a highest refractive index among the first to sixth lenses.

Abstract: The present disclosure discloses a camera optical lens. The camera optical lens including, in an order from an object side to an image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens. The first lens is made of glass material, the second lens is made of plastic material, the third lens is made of glass material, the fourth lens is made of plastic material, the fifth lens is made of plastic material, and the sixth lens is made of plastic material. The camera optical lens further satisfies specific conditions.

Abstract: An imaging lens for a solid-state image sensor includes five lenses, arranged in order from an object side to an image side, a first lens with positive refractive power having a convex surface on the object side, a second lens with negative refractive power, a third lens with positive or negative refractive power having a meniscus shape with a convex surface on the object side and a concave surface on the image side near an optical axis, a fourth lens as a double-sided aspheric lens, having a concave surface on the image side near the optical axis, and a fifth lens as a double-sided aspheric lens, having a concave surface on the image side near the optical axis; wherein the first to fifth lenses are made of plastic materials.

Abstract: An imaging lens includes a first lens group having positive refractive power and a second lens group having negative refractive power, arranged in this order from an object side to an image plane side. The first lens group includes a first lens having positive refractive power, a second lens having positive refractive power, and a third lens having negative refractive power. The second lens group includes a fourth lens having positive refractive power, a fifth lens, and a sixth lens having negative refractive power. The first lens has a specific focal length. The first to third lenses have specific Abbe's numbers.

Abstract: Present embodiments provide for a mobile device and an optical imaging lens thereof. The optical imaging lens comprises six lens elements positioned sequentially from an object side to an image side. Through controlling the convex or concave shape of the surfaces and/or the refracting power of the lens elements, the optical imaging lens shows better optical characteristics and the total length of the optical imaging lens is shortened.

Abstract: An image lens assembly includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element has positive refractive power. The third lens element has refractive power. The fourth lens element has refractive power. The fifth lens element with negative refractive power has a concave object-side surface, wherein both of the surfaces of the fifth lens element are aspheric. The sixth lens element with refractive power has a concave image-side surface, wherein the image-side surface thereof has at least one inflection point, and both of the surfaces of the sixth lens element are aspheric. The image lens assembly has a total of six lens elements with refractive power.

Abstract: A lens module may include a first lens having positive refractive power, a second lens having positive refractive power, a third lens having refractive power, a fourth lens having positive refractive power, a fifth lens having negative refractive power, and a sixth lens having negative refractive power and having one or more inflection points formed on an image-side surface thereof. An overall focal length of the lens module f and a focal length of the first lens f1 may satisfy the following Conditional Expression: 1.0<f1/f<2.0.

Abstract: There is provided a lens module including: a first lens having positive refractive power; a second lens having positive refractive power; a third lens having negative refractive power; a fourth lens having refractive power; a fifth lens having positive refractive power; and a sixth lens having refractive power and a shape in which an image side surface thereof is concave toward an image side.

Abstract: An imaging lens includes a positive first lens; a negative second lens with a meniscus lens shape directing a convex surface thereof to an object side near an optical axis; a positive third lens; a negative fourth lens with a meniscus lens shape directing a concave surface thereof to the object side near the optical axis; a negative fifth lens with a meniscus lens shape directing a convex surface thereof to the object side near the optical axis, arranged in this order from the object side. The imaging lens satisfies the following conditional expressions when the first lens has a focal length f1, the second lens has a focal length f2, the third lens has a focal length f3, the fourth lens has a focal length f4, and the fifth lens has a focal length f5: f1<f3 and |f2|<f3 f3<|f4| and |f2|<|f5|.

Abstract: Provided are a photographing lens and an electronic apparatus including the same. The photographing lens includes: a first lens that includes a convex object-side surface and has a positive refractive power; a second lens that includes a convex image-side surface and has a positive or negative refractive power; a third lens that has a negative refractive power; a fourth lens that has a positive or negative refractive power; a fifth lens that includes a convex image-side surface and has a positive refractive power; and a sixth lens that includes an image-side surface that is concave near an optical axis, and has a negative refractive power, wherein the first through sixth lenses are sequentially arranged from an object side.

Abstract: An imaging lens system has, from an object side, at least one positive lens element convex to the object side, a negative lens element, and at least one lens element having an aspherical surface. The positive and negative lens elements are arranged next to each other. The formulae 0.1<Ton/Dopn<7, 0.1<(Rona?Ronb)/(Rona+Ronb)<1.5, and 0.3<Y?/TL<0.

Abstract: A zoom lens includes first to third lens units having positive, negative, and positive refractive power, respectively, and a rear lens group having positive refractive power. An aperture stop is arranged between a lens surface of the second lens unit closest to the image side and a lens surface of the third lens unit closest to the image side. The third lens unit includes first and second positive lenses each including an aspheric surface, and a negative lens. In the third lens unit, a refractive index of the first positive lens, and an Abbe number and relative partial dispersion of the second positive lens are appropriately set.

Abstract: An optical image lens system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element and the third lens element have positive refractive power. The fourth lens element has refractive power. The fifth lens element with positive refractive power is made of plastic and has a convex object-side surface and a concave image-side surface, wherein at least one surface thereof is aspheric. The sixth lens element with refractive power is made of plastic and has a concave image-side surface, wherein at least one surface thereof is aspheric, and the image-side surface thereof changes from concave at a paraxial region to convex at a peripheral region.

Abstract: An imaging lens includes: a first lens having positive refractive power; a second lens having positive refractive power; a third lens having negative refractive power; a fourth lens having positive refractive power; a fifth lens having positive refractive power; and a sixth lens having negative refractive power in vicinity of an optical axis and having positive refractive power in a peripheral portion. The first to sixth lenses are arranged in order from object plane.

Abstract: An optical photographing lens system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element has positive refractive power. The third lens element has negative refractive power. The fourth lens element with refractive power has a convex object-side surface and a concave image-side surface, wherein the surfaces thereof are aspheric. The fifth lens element with positive refractive power has a convex image-side surface, wherein the surfaces thereof are aspheric. The sixth lens element with negative refractive power has a concave image-side surface, wherein the image-side surface changes from concave at a paraxial region thereof to convex at a peripheral region thereof, and the surfaces thereof are aspheric.

Abstract: Disclosed herein is an imaging lens including: a first lens having positive (+) power; a second lens having positive (+) power; a third lens having positive (+) or negative (?) power; a fourth lens having positive (+) or negative (?) power; a fifth lens having positive (+) or negative (?) power; and a sixth lens having negative (?) power.

Abstract: Wide-angle imaging lens arrangements and methods are described for use with an image projector system including a display. A plurality of no more than six lenses can be arranged to receive an object image that emits from the display to propagate through the plurality of lenses to produce a high-quality projected image on a screen. The image projector system has a low f-number, low height profile and high resolution.

Abstract: An image capturing lens assembly includes, 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 positive refractive power, a third lens element with refractive power, a fourth lens element with refractive power, a fifth lens element with refractive power having a convex image-side surface, and a sixth lens element with refractive power having a concave image-side surface. An object-side surface and the image-side surface of the sixth lens element are aspheric, and the sixth lens element has at least one inflection point formed on the image-side surface thereof.

Abstract: An optical image capturing lens assembly includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, and a sixth lens element. The first lens element with positive refractive power has a convex object-side surface. The object-side surface and the image-side surface of the fifth lens element are aspheric and at least one of the object-side surface and the image-side surface has at least one inflection point formed thereon. The sixth lens element with negative refractive power has a concave object-side surface and a convex image-side surface, wherein the object-side surface and the image-side surface of the sixth lens element are aspheric.

Abstract: An image capturing lens assembly includes, 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 positive refractive power, a third lens element with refractive power, a fourth lens element with refractive power, a fifth lens element with refractive power having a convex image-side surface, and a sixth lens element with refractive power having a concave image-side surface. An object-side surface and the image-side surface of the sixth lens element are aspheric, and the sixth lens element has at least one inflection point formed on the image-side surface thereof.

Abstract: There is provided a projection lens unit for a pico-projector which comprises a lens array, a color composition prism, a cover glass and an image panel, the projection lens unit characterized in that: the lens array includes 1st to 6th lenses sequentially arrayed from a screen on which an image is projected, the 1st lens includes a stop side formed on a 1st side of the 1st lens, the stop side stops the passage of light, to perform the function of a diaphragm aperture, light passing from the 1st lens to the 6th lens travels in only one direction of the lens sides based on the diaphragm aperture, and parts of the lens sides through which the light does not pass are cut so that the whole height of the lens array is reduced.

Abstract: An optical system for imaging an object on an image acquisition unit includes a first lens unit, a second lens unit, a third lens unit, a fourth lens unit, a fifth lens unit, and a sixth lens unit disposed from the object in the direction of the image acquisition unit. The second lens unit is manufactured from a material whose deviation of the relative partial dispersion fulfills the condition: ??gF>0.025. The third lens unit is manufactured from a material whose deviation of the relative partial dispersion fulfills the condition: ??gF<?0.0015. The fifth lens unit is manufactured from a material whose deviation of the relative partial dispersion fulfills the condition: ??gF<?0.005. According to the disclosed system, the secondary spectrum is reduced and a relative aperture is sufficient so that the optical system is usable in a telescopic sight.

Abstract: An image reading lens is provided and includes: first, second and third lens groups arranged on the object side with respect to the aperture stop; and fourth, fifth and sixth lens groups arranged on the image side. At least all positive lenses, in each lens group, satisfy conditional expression (1) below. At least two positive lenses of the first to third lens groups and at least two positive lens of the fourth to sixth lens groups satisfy the conditional expression (2) below. In the conditional expressions, ?d represents Abbe number at the d-line, and ??g,d represents abnormal dispersion. ?d>60.0??(1) ??g,d>0.

Abstract: An apparatus and method that provides for improved optical communication between at least one source and at least one destination, with reduced loss of power and superior retention of the quality of a signal when compared with the prior art. The apparatus has a body having at least one integrated optical channel along which a light signal is transmitted via an N-fold plurality of lenses. A light signal transmitted along the integrated optical channel is repeatedly refocused along the optical axis and is then highly focused at the second end. Optionally, the light signal can be switched, attenuated, filtered, tapped or monitored by positioning appropriate optical devices between the lenses.

Abstract: When a projection lens system used for a rear projection type image display apparatus has a first lens group having an aspherical lens surface, a second lens group, a third lens group sharing almost all the positive refractive power of the overall system, a fourth lens group having an aspherical lens surface, a fifth lens group, and a sixth lens group including a lens having a profile of aspherical surface in which the concave surface thereof faces the screen side and the refractive power in the marginal area is weaker than the refractive power around the optical axis, a projection lens system having a large aperture ratio (low F-number), high focus, wide field angle, and sufficient marginal light amount ratio can be realized at a low cost. When a predetermined opening portion is formed in the projection lens and lens barrel, the lens elements are cooled by air suction and exhaust and the lowering of the lens performance due to temperature change can be prevented.

Abstract: A Gaussian lens for photography includes, in order from the object side, a front lens group, a stop, and a rear lens group. The front lens group is formed of, in order from the object side, a first lens element and a second lens element, each of positive meniscus shape with their convex surfaces on the object side, and a third lens element that has a negative meniscus shape with its convex surface on the object side. The rear lens group is formed of, in order from the object side, a fourth lens element which has a negative meniscus shape with its concave surface on the object side, and fifth and sixth lens elements each of which is a positive meniscus lens with its convex surface on the image side. Each lens element surface is spaced from any adjacent lens elements so that no lens element surfaces are joined to form a combined lens.

Abstract: A projection optical system that projects an image on a first side onto a second plane through a plurality of lenses includes the following elements in order from the first side to the second plane: a first lens group that has a negative refractive power, a second lens group that has a positive refractive power, a third lens group that has a negative refractive power, a fourth lens group that has an aperture stop in the optical path, and a fifth lens group that has a positive refractive power. A clear aperture of a lens surface or an outer diameter of a lens in the projection optical system has a relative maximum in the second lens group, a relative minimum in the third lens group, and a relative maximum in the third-fifth lens groups, and has only one significant minimum between the first side and the second plane.

Abstract: Six-component projection lens systems (13) for use in CRT projection televisions (10) are provided. To provide an improved overall modulation transfer function across the field of view of the lens, the system's first lens element (L1) has an object side surface (S2) which has a best fit spherical surface which is convex to the CRT (16). To provide partial axial color correction, the system's second lens element (L2) is made of a high dispersion material, such as styrene.

Abstract: A lens system for reading images, consisting of six lens elements of positive, positive, negative, negative, positive and positive refractive power, respectively, in order from the object side, with a stop positioned between the third lens element and the fourth lens element. The first lens element L1 and the second lens element L2 each has a convex surface on the object side. The third lens element L3 has a concave surface on the image side, and the fourth lens element L4 has a concave surface on the object side. A fifth lens element L5 and a sixth lens element L6 each has a convex surface on the image side. At least one of the two pairs of lens elements L2, L3, and L4, L5 are coupled together, and specified conditions are satisfied in order to provide a lens having high resolution for color images.

Abstract: When a projection lens system used for a rear projection type image display apparatus has a first lens group having an aspherical lens surface, a second lens group, a third lens group sharing almost all the positive refractive power of the overall system, a fourth lens group having an aspherical lens surface, a fifth lens group, and a sixth lens group including a lens having a profile of aspherical surface in which the concave surface thereof faces the screen side and the refractive power in the marginal area is weaker than the refractive power around the optical axis, a projection lens system having a large aperture ratio (low F-number), high focus, wide field angle, and sufficient marginal light amount ratio can be realized at a low cost. When a predetermined opening portion is formed in the projection lens and lens barrel, the lens elements are cooled by air suction and exhaust and the lowering of the lens performance due to temperature change can be prevented.

Abstract: A Gaussian lens for photography includes, in order from the object side, a front lens group, a stop, and a rear lens group. The front lens group is formed of, in order from the object side, a first lens element and a second lens element, each of positive meniscus shape with their convex surfaces on the object side, and a third lens element that has a negative meniscus shape with its convex surface on the object side. The rear lens group is formed of, in order from the object side, a fourth lens element which has a negative meniscus shape with its concave surface on the object side, and fifth and sixth lens elements each of which is a positive meniscus lens with its convex surface on the image side. Each lens element surface is spaced from any adjacent lens elements so that no lens element surfaces are joined to form a combined lens.

Abstract: A photographing lens includes a front lens unit and a rear lens unit that are arranged in this order from the object side. The front lens unit comprises, in this order from the object side, a first lens element which is a positive meniscus lens having a convex surface facing the object side, a second lens element which is a positive meniscus lens having a convex surface facing the object side and a third lens element that is cemented to the second lens element. The third lens element is a negative meniscus lens having a convex surface facing the object side. The rear lens group comprises, in this order from the object side, a fourth lens element which is a positive meniscus lens having a convex surface facing the image side, a fifth lens element which is a negative meniscus lens having a concave surface facing the object side and a sixth lens element which is cemented to the fifth lens element. The sixth lens element is a positive meniscus lens having a convex surface facing the image side.

Abstract: A photographic lens comprising: a front lens group and a rear lens group that are arranged in order from the object side; wherein the front lens group comprises, in order from the object side, a first lens element which is a positive meniscus lens having a convex surface facing the object side, a second lens element which is a positive meniscus lens having a convex surface facing the object side, and a third lens element that is cemented to the second lens element, the third lens element being a negative meniscus lens having a convex surface facing the object side; wherein said rear lens group comprises, in order from the object side, a fourth lens element which is a positive meniscus lens having a convex surface facing the image side; a fifth lens element which is a negative meniscus lens having a concave surface facing the object side; a sixth lens element that is cemented to the fifth lens element, the sixth lens element being a positive meniscus lens having a convex surface facing the image side; and wher

Abstract: A lens used for picture image reading that consists of six lens elements arranged as a deformed Gauss type lens, and an improved image reader which uses the lens. By establishing the lens elements to be of prescribed shapes and so that certain specified conditions are satisfied, a lens having high resolution, with the various aberrations being favorably corrected over a wide range of wavelengths, is provided. Further, the manufacturing costs of the lens are lowered. The lens includes, in order from the object side: a first lens element L.sub.1 of a positive meniscus shape, a second lens element L.sub.2 of a positive meniscus shape, a third lens element L.sub.3 of a negative meniscus shape with its concave surface on image side, a fourth lens element L.sub.4 of a negative meniscus shape with its concave surface on the object side, a positive fifth lens element L.sub.5, and a positive sixth lens element L.sub.6 with its convex surface on the image side.

Abstract: A fast photographic lens system comprises a first lens having a positive refractive power, a convex-shaped outer face and a flat inner face; a second lens having a positive refractive power, a convex-shaped outer face and a concave-shaped inner face; a third lens having a negative refractive power, a slightly convex-shaped outer face, and a concave-shaped inner face; a fourth lens having a negative refractive power and a concave-shaped inner face; a fifth lens, joined with the fourth lens, and having a positive refractive power, a relatively flat inner face and a convex-shaped outer face; a sixth lens having a positive refractive power, a slightly concave-shaped inner face and a convex-shaped outer face; and a seventh lens, having both convex-shaped inner and outer faces.

Abstract: A photographic lens system comprises, in order from the object end, a positive power element having a concave image end surface, an element having a concave image end surface, a negative power element, a positive power element, a meniscus element of a positive power having a concave object end surface, and a doublet comprising a negative power element having a concave object end surface and a positive power element having a convex image end surface, and satisfies the following conditions:0.28<f/f4<2.55 (1)0<f/f5<1.80 (2)-1.15<f/f67<0.65 (3)-0.55<(R6-R7)/(R6+R7)<-0.17 (4)0.03<(R10-R11)/(R10+R11)<0.31 (5)-0.45<(R11-R14)/(R11+R14)<0.10 (6).

Abstract: An objective lens comprising, respectively from the object: a first element of a positive lens, at the object end thereof, having a convex surface; a second element of a positive meniscus lens, at the object end thereof, having a convex surface; a third element of a negative lens, at the image end thereof, having a concave surface; a fourth element of a single lens or a cemented lens, at the object end thereof, having a convex surface, wherein the cemented lens includes two or three lenses; a fifth element of a negative lens, at the object end thereof, having a concave surface; and a sixth element of a positive lens, at the object end thereof, having a convex surface. The objective lens satisfies the following three conditional equations, assuming that "f" designates the focal distance of the entire lens system:0.44f<R II<0.65f (1)0.63f<R IV<1.00f (2)0.55f<S III+D IV<0.