Abstract: An optical lens system for taking image comprises, in order from the object side to the image side: a first lens element with positive refractive power having a convex object-side surface; an aperture stop; a second lens element with negative refractive power; a third lens element having a convex object-side surface; and a fourth lens element with negative refractive power having a concave object-side surface, an image-side surface of the fourth lens element being aspheric and formed with inflection points. A distance from the image-side surface of the fourth lens element to an image plane along an optical axis being BFL, a total track length of the optical lens system for taking image being TTL, and they satisfy the relation: BFL/TTL>0.12. In the optical lens system for taking image, the number of lens elements with refractive power being limited to four.

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

Abstract: An imaging lens comprises a first lens (L1), a second lens (L2), a third lens (L3), and a fourth lens (L4), which are arranged in ascending sequence, starting from the lens nearest to the object. The first lens (L1) has a double-convex shape and positive refractive power. The second lens (L2) has a double-concave shape and negative refractive power. The third lens (L3) has a meniscus shape with its convex surface facing an image plane, and has positive refractive power. The fourth lens (L4) has a meniscus shape with its convex surface facing the object. A chromatic aberration occurred in the first lens (L1) is corrected by the second lens (L2). A chromatic aberration occurred in the third lens (L3) is corrected by the fourth lens (L4).

Abstract: An optical lens system for taking image comprises: a first lens element with positive refractive power, an Abbe Number of the first lens element being V1, and it satisfying the relation: 50<V1<60; a second lens element with negative refractive power having a concave object-side surface and a convex image-side surface; a third lens element having a convex object-side surface and a concave image-side surface, at least one of the object-side and the image-side surfaces of the third lens element being aspheric; a fourth lens element having at least one aspheric surface; and an aperture stop being located in front of the second lens element.

Abstract: An imaging lens is provided and includes: in order from an object side of the imaging lens, a first lens group having a positive power as a whole; a second lens group, in which an object-side surface of a lens closest to the object side is concave toward the object side; a third lens group of a single lens having a positive power; and a fourth lens group having a negative power as a whole.

Abstract: The present invention provides an imaging optical lens assembly including, in order from the object side to the image side: a first lens group comprising a first lens element with positive refractive power, no lens element with refractive power being disposed between the first lens element and an imaged object, the first lens element being the only lens element with refractive power in the first lens group; and a second lens group comprising, in order from the object side to the image side: a second lens element with negative refractive power; a third lens element; and a fourth lens element; wherein focusing adjustment is performed by moving the first lens element along an optical axis, such that as a distance between the imaged object and the imaging optical lens assembly changes from far to near, a distance between the first lens element and an image plane changes from near to far; and wherein the number of the lens elements with refractive power in the imaging optical lens assembly is N, and it satisfies t

Abstract: An imaging module includes an imaging lens system and an image sensor. The imaging lens system includes a first lens, a second lens, a third lens, and a fourth lens. The imaging module satisfies the formulas, 2.4<F1/TTL<3.0, ?7.0<F2/TTL<?5.5, 0.95<F3/TTL<2.0, and ?3.5<F4/TTL<?2.5, wherein the TTL is the distance from the object surface of the first lens to the sensing surface of the image sensor on the optical axis of the imaging lens system, the F1 is the focal length of the first lens, the F2 is the focal length of the second lens, the F3 is the focal length of the third lens, and the F4 is the focal length of the fourth lens.

Abstract: An image taking lens 1 comprises a stop 2, a first lens 3 having a positive power and biconvex configuration, a second lens 4 having a negative power and having a meniscus configuration in which a concave surface is disposed to face an object, a third lens 5 having a positive power and a meniscus configuration in which a convex surface is disposed to face an image, and a fourth lens 6 having a negative power and a meniscus configuration in which a convex surface is disposed to face the object, which are arranged in this order from the object. The lenses 3 to 6 satisfy the following formulae (1) to (4), 3.00<F1/d1<10.00??(1) ?20.0<F2/d3<?10.0??(2) 50.0<?1<60.0??(3) 20.0<?2<30.0??(4) hereupon, F1: focal length of the first lens; F2: focal length of the second lens; d1: a center thickness of the first lens; d3: a center thickness of the second lens; ?1: an Abbe's number of the first lens; and ?2: an Abbe's number of the second lens.

Abstract: An imaging lens is provided and includes: in order from an object side of the imaging lens, a first lens having a positive refractive power and having a convex surface on the object side; a second lens having a negative refractive power and having a concave surface on the object side; a third lens having a positive refractive power in the vicinity of an optical axis thereof; and a fourth lens of a meniscus lens having a negative refractive power and having a convex surface on the object side, the imaging lens satisfying the specific conditional expressions.

Abstract: An image pickup lens includes, in order from an object side thereof: a aperture stop; a first lens having a positive refractive power; a second lens having a negative refractive power; a third lens having a positive refractive power; and a fourth lens having a negative refractive power and having a biconcave shape including an aspheric surface. The image pickup lens satisfies the predetermined conditions according to focal lengths of the first lens and the third lens.

Abstract: An imaging lens includes an imaging lens system and an image sensor. The imaging lens system includes a first lens, a second lens, a third lens, and a fourth lens. The imaging module satisfies the formulae (1) D/T?1.1, (2) ?3.5<R2/F1<?1.5, (3) ?2.5<R3/F2<?0.5, and (4) 1.5<|R7/F4|<3.5, wherein D is the diagonal length of the sensing area of the image sensor, T is the length from the object surface of the first lens to the sensing surface of the image sensor, R2 is the radius of curvature of the image side surface of the first lens, R3 is the radius of curvature of the object side surface of the second lens, R7 is the radius of curvature of the object side surface of the fourth lens, F1, F2, F4 are the corresponding focal length of the first lens, the second lens, and the third lens.

Abstract: An imaging module includes an imaging lens system and an image sensor. The imaging lens system includes a first lens, a second lens, a third lens, and a fourth lens. The imaging module satisfies the formulas, 2.4<F1/TTL<3.0, ?7.0<F2/TTL<?5.5, 0.95<F3/TTL<2.0, and ?3.5<F4/TTL<?2.5, wherein the TTL is the distance from the object surface of the first lens to the sensing surface of the image sensor on the optical axis of the imaging lens system, the F1 is the focal length of the first lens, the F2 is the focal length of the second lens, the F3 is the focal length of the third lens, and the F4 is the focal length of the fourth lens.

Abstract: Disclosed are an imaging lens having a small size and high imaging performance, a camera module that is provided with the imaging lens and can obtain a high-resolution image signal, and an imaging apparatus. An imaging lens includes a first lens having a positive power, a second lens having a negative power, a third lens that has a positive power and includes a convex image-side surface, and a fourth lens that has a negative power and includes an object-side surface which is concave or flat near an optical axis. The first to fourth lenses are arranged in this order from an object side, and the imaging lens satisfies Conditional expression 1 given below: 0.5<(|R2|?R1)/(R1+|R2|)??[Conditional expression 1] (where R1 indicates the curvature radius of an object-side surface of the first lens and R2 indicates the curvature radius of an image-side surface of the second lens).

Abstract: An optical lens system for taking image comprises: in order from the object side to the image side: an aperture stop; a first lens element with positive refractive power having a convex object-side surface, a second lens element with negative refractive power; a third lens element with positive refractive power having a concave object-side surface and a convex image-side surface; a plastic fourth lens element with negative refractive power having a concave image-side surface, the object-side and the image-side surfaces of the fourth lens element being aspheric. A focal length of the optical lens system for taking image is f, a focal length of the first lens element and the second lens element combined is f12, and they satisfy the relation: 0.98<f/f12<1.82.

Abstract: A fixed focus lens includes, numbered in order of location from an object side to an image side, a first lens, a second lens, a third lens, and a fourth lens. The first lens is a biconvex lens with a positive refractive power, and the second lens is a convex-concave lens with a negative refractive power. The third lens is a concave-convex lens with a positive refractive power, and the fourth lens is an aspherical lens having a negative refractive power in the centre portion thereof and a positive refractive power at the periphery portion thereof. The fixed focus lens satisfies the condition: 1.0>|(1/r2?1/r1)|>0.6, where r1 denotes the radius of curvature of a front surface of the second lens and r2 denotes the radius of curvature of a rear surface of the first lens.

Abstract: A miniature image capture lens is disclosed, comprising an aperture diaphragm having an aperture through which an image is captured and a wafer-level lens system, comprising a first lens group including a first substrate, a first lens disposed on a first side of the first substrate and a second lens disposed on a second side of the first substrate, and a second lens group including a second substrate, a third lens disposed on a first side of the second substrate and a fourth lens disposed on a second side of the second substrate. The first lens, the second lens, the third lens and the fourth lens are aspherical and the miniature image capture lens meets the following condition: L/fe<1.6; f1/fe=0.5˜1.5; f2/fe=?1˜?3; Tgroup2/TBFL=0.8˜1.2; Tair/Tlens2=0.4˜0.

Abstract: An optical lens system for taking image comprises four lens elements from the object side to the image side: a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power having a concave object-side surface and a concave image-side surface, at least one of the object-side surface and the image-side surface of the second lens element being aspheric, inflection points being formed on the image-side surface of the second lens element; a third lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a fourth lens element with negative refractive power; and an aperture stop being located between the object side and the second lens element.

Abstract: An image pickup lens relating to the present invention is a lens for forming an image of a subject onto a photoelectric converter of a solid-state image pickup element. The image pickup lens includes, in order from an object side thereof: an aperture stop; a first lens with a positive refractive power; a second lens in a meniscus shape with a negative refractive power, whose object side surface is a convex surface; a third lens with a positive refractive power; and a fourth lens with a negative refractive power. The image pickup lens satisfies a predetermined conditions relating to a curvature radius of the object side surface of the second lens and an Abbe number of the second lens.

Abstract: An image pickup lens includes, in order from an object side to an image side, an aperture stop, a first lens element having a positive refractive power, a second lens element having a negative refractive power and a biconcave shape, a third lens element having a positive refractive power and a meniscus shape whose concave surface faces the object side, and a fourth lens element having a negative refractive power. In the image pickup lens, the following conditional expressions are satisfied, 0.20<f/|f2|<0.9 ?d1??d2>25 where f denotes the focal length of the entire lens system, f2 denotes the focal length of the second lens element, ?d1 denotes the Abbe number of the first lens element, and ?d2 denotes the Abbe number of the second lens element.

Abstract: It is to provide a large-diameter imaging lens that can suppress reduction of peripheral light amount, achieve size and weight reduction, and maintain excellent optical performance. The imaging lens comprises, in order from an object side to an image surface side, a first lens having a positive power whose convex surface faces the image surface side, a diaphragm, a second lens having a negative power whose convex surface faces the image surface side, a third lens having a positive power, and a fourth lens having a negative power, wherein conditions expressed by 0.3?f/f1?1.7 and ?2.7?f/f2??0.25 (where, f: focal distance of the entire lens system, f1: focal distance of the first lens, and f2: focal distance of the second lens) are to be satisfied.

Abstract: An image pickup lens includes: a first lens having a positive refracting power; an aperture stop for adjusting the amount of light; a second lens having a concave face directed to the object side and having a negative refracting power; a third lens having a concave face directed to the object side and having a positive refracting power; and a fourth lens having a negative refracting power; the first lens, aperture stop, second lens, third lens, and fourth lens being disposed in order from the object side.

Abstract: A first lens (L1), a second lens (L2), a third lens (L3), and a fourth lens (L4) are arranged in this order from an object side. The first lens (L1) has a biconvex shape and a positive refracting power. The second lens (L2) has a meniscus shape that is convex toward the object side, and has a negative refracting power. The third lens (L3) has a meniscus shape that is convex toward an image side, and has a positive refracting power. The fourth lens (L4) has a meniscus shape that is convex toward the object side, and has a negative refracting power. A chromatic aberration generated by the first lens (L1) is corrected by the second lens (L2). A chromatic aberration generated by the third lens (L3) is corrected by the fourth lens (L4).

Abstract: A zoom lens including a broad picture angle of 60 to 100 degrees as a photographic picture angle of the wide-angle end state, and having a magnification ratio of about three to six times, small front gem diameter, excellent compactness and high image formation performance, which is used in a video camera or a digital still camera, and an image pick-up apparatus using such a zoom lens. A zoom lens (20), consisting of plural groups and serving to change group spacing or spacings to thereby perform a magnification changing or adjusting operation, comprises a first lens group GR1 having positive refractive power, a second lens group GR2 having negative refractive power and a third lens group GR3 having positive refractive power which are arranged in order from the object side, and a last group GRR arranged at the side closest to the image surface and having negative refractive power, wherein the first lens group GR1 is constituted by single positive lens G1, and satisfies the following conditional formulas. 0.

Abstract: A lens system comprising an inner lens structure and an outer lens structure. The inner lens structure comprises an inner positive lens, a first transparent substrate and an inner negative lens. The outer lens structure comprises an outer positive lens, a second transparent substrate and an outer negative lens.

Abstract: A photographic lens comprising a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, and a fourth lens having a negative refractive power, wherein the lenses are numbered in order of location from the object, and wherein a surface of the fourth lens toward the object is an aspheric surface having an inflection point.

Abstract: An image pickup lens includes, in order from an object side, a first lens element having a positive refractive power and a convex surface facing the object side, an aperture stop adjusting the amount of light, a second lens element having a negative refractive power, a third lens element having a positive refractive power and a concave surface facing the object side, and a fourth lens element having a negative refractive power. In the image pickup lens, the following conditional expressions are satisfied, 0.6<|f2/f|<1.8 0?f2/R4<1.7 where f denotes a focal length of an entire lens system, f2 denotes a focal length of the second lens element, and R4 denotes a curvature radius of an object-side surface of the second lens element.

Abstract: An imaging lens includes, in the order from the object side to the image side, a first lens of positive refraction power, a second lens of negative refraction power, a third lens of positive refraction power, and a fourth lens of negative refraction power. The imaging lens satisfies the formulae (1) 1<T/F<1.4; (2) R3/F>4; and (3) S1/S2>3, where T is the overall length of the imaging lens, F is the focal length of the imaging lens, R3 is the radius of curvature of the object-side surface of the second lens, S1 is the vertical distance from the edge to the center of the image-side surface of the third lens, and S2 is the horizontal distance from the edge to the center of the image-side surface of the third lens.

Abstract: An image pickup lens includes: an aperture stop; a first lens having a positive power and including a convex surface facing an object side; a second lens having a negative power and including a concave surface facing an image side; a third lens in a meniscus shape having a positive power and including a convex surface facing the image side; and a fourth lens in a meniscus shape having a negative power and including a convex surface facing the object side. The image pickup lens satisfies predetermined conditions relating to a composite focal length of the first through third lenses, a length of an air space between the third lens and the fourth lens along the optical axis, and a curvature radius of a surface of the second lens facing the image side.

Abstract: An optical lens system for taking image comprises four lens elements from the object side to the image side: a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power having a concave object-side surface and a concave image-side surface, at least one of the object-side surface and the image-side surface of the second lens element being aspheric, inflection points being formed on the image-side surface of the second lens element; a third lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a fourth lens element with negative refractive power; and an aperture stop being located between the object side and the second lens element.

Abstract: An imaging lens includes in order from an object side, a stop and a first lens to a fourth lens. Both the surfaces of a third lens have surfaces including at least one inflection point, and an inclination of each surface at the terminal end part of a periphery within an effective diameter collapses toward the image side. And 0.1<D3/D4<2.0, ?d1??d2>25, 0.4<f1/f3<1.6 and 0.3<f/f3<1.5 are satisfied, where D3 is an air space on an optical axis between the first lens and the second lens, D4 is a central thickness of the second lens, ?d1 and ?d2 are Abbe numbers of the first lens and the second lens, f1 and f3 are focal lengths of the first lens and the third lens and f is a focal length of an entire system.

Abstract: A subminiature optical system including: a first lens that is a biconvex lens with a positive refractive power; a second lens with a negative refractive power, the second lens formed in a meniscus shape convex toward an object side; a third lens with a positive refractive power, the third lens formed in a meniscus shape convex toward an image side; and a fourth lens with a negative refractive power, wherein a size in a direction of an optical axis satisfies Condition 1, and the refractive power of the first lens satisfies Condition 2, 1.2<TL/f<1.3 . . . Condition 1, 0.6<f1/f1<0.8 . . . Condition 2 where TL indicates a length from an aperture stop to an image-side surface, f indicates an effective focal length of the overall optical system, and f1 indicates a focal length of the first lens.

Abstract: A compact lens system that includes a first lens that is a meniscus lens with positive refractive power and having aspheric surfaces on both sides, and a convex surface on a surface facing an object; a second lens formed of a biconcave lens having aspheric surfaces on both sides; a third lens having aspheric surfaces on both sides and having positive refractive power; and a fourth lens formed of a biconcave lens having aspheric surfaces on both sides and an inflection point on an upper aspheric surface. The first through fourth lenses are arranged sequentially from the object, and an aperture diaphragm is disposed on the object side of the first lens.

Abstract: In a photographing lens unit, an aperture diaphragm, a first lens having positive refractive power, a second lens having negative refractive power, a third lens of a positive meniscus lens with a concave surface on the object side, an ND filter, a fourth lens of a negative meniscus lens with a convex surface on the object side, an IR cut filter, and an imaging element are disposed in order from the object side to the imaging element side. In the third lens, a surface shape on the object side changes from concave to convex as it is away from an optical axis, and a surface shape on the image side changes from convex to concave as it is away from the optical axis. In the fourth lens, a surface shape on the object side changes from convex to concave as it is away from the optical axis.

Abstract: A lens system includes a positive refractive power first lens, a negative refractive power second lens, a positive refractive power third lens, and a negative refractive power fourth lens in that order from the object side of the lens system. Wherein the lens system satisfies the following conditions: (1) D1/D2<1.6; and (2) R2/F1>1.8, wherein, D1 is the effective radius of a surface of the third lens facing the image side of the lens system, D2 is a distance from the top point of a surface to the optical center of the third lens, R2 is the radius of curvature of a surface of the first lens facing the image side of the lens system, and F1 is a focal length of the first lens.

Abstract: An eyepiece includes, in order from the object side, a first lens with positive power, a second lens with positive power, and a third lens with negative power. The first lens is a positive meniscus lens with a convex surface facing the object side, and the eyepiece fails to have a fourth lens. The eyepiece satisfies the following conditions: 0.6<f1/f<1.2 ?2.0<f1-2/f3<?1.0 ?0.45<f3/f<?0.25 where f1 is the focal length of the first lens; f1-2 is a combined focal length of the first and second lenses and is a focal length where a diopter is ?1 m?1 when the focal length of the eyepiece is changed; f3 is the focal length of the third lens; and f is the focal length of the entire system of the eyepiece and is a focal length where a diopter is ?1 m?1 when the focal length of the eyepiece is changed.

Abstract: The present invention provides an image pickup lens for forming a light flux from a subject into an image on a photo-electric converter of a solid image pickup element, and the image pickup lens includes, in order from an object side thereof: and aperture stop; a first lens having a positive refractive power; a second lens having a negative refractive power; a third lens having a positive refractive power; and a fourth lens having a negative refractive power. The fourth lens includes a concave surface facing the object side and at least one optical surface has an aspheric shape in the fourth lens. The image pickup lens satisfies the predetermined condition according to a curvature radius of the surfaces of the fourth lens and a focal length.

Abstract: An exemplary imaging lens includes, in this order from the object side to the image side thereof, a first lens of positive refraction power, a second lens of negative refraction power, a third lens of positive refraction power, and a fourth lens of negative refraction power. The imaging lens satisfies the formulas of: (1) 0.5<F1/F<1; (2) R6>R5>R7, where F1 is the focal length of the first lens, F is the effective focal length of the imaging lens, R5 is the radius of curvature of the object-side surface of the third lens, R6 is the radius of curvature of the image-side surface of the third lens, and R7 is the radius of curvature of the object-side surface of the fourth lens.

Abstract: An optical lens system includes a first lens having positive lens power; a second lens having negative lens power; a third lens having positive lens power; and a fourth lens having negative lens power, wherein the first through fourth lenses are sequentially arranged from a subject.

Abstract: It is to provide a large-diameter imaging lens that can suppress reduction of peripheral light amount, achieve size and weight reduction, and maintain excellent optical performance. The imaging lens comprises, in order from an object side to an image surface side, a first lens having a positive power whose convex surface faces the image surface side, a diaphragm, a second lens having a negative power whose convex surface faces the image surface side, a third lens having a positive power, and a fourth lens having a negative power, wherein conditions expressed by 0.3?f/f1?1.7 and ?2.7?f/f2??0.25 (where, f: focal distance of the entire lens system, f1: focal distance of the first lens, and f2: focal distance of the second lens) are to be satisfied.

Abstract: A picture-taking lens for forming an image of an object image on a solid picture-taking element, comprising in order from the object side: a first lens having a positive refractive power and directing a convex surface toward the object side; an aperture stop, a second lens having a positive refractive power and a meniscus shape directing a convex surface toward the image side; and a third lens having a negative refractive power and directing a concave surface toward the image side, wherein the picture-taking lens satisfies the following conditional expression: 0.20<R1/f<0.42, 0.10<D2/f<0.40, where R1 is a radius of curvature of the object side surface of the first lens, D2 is an air gap on the axis between the first lens and the second lens, f is a focal length of a whole system of the picture-taking lens.

Abstract: An imaging lens is provided and includes: in order from an object side of the imaging lens, a first lens having a positive power; a second lens having a negative power; a third lens having a positive power and having a convex surface on an image side thereof; and a fourth lens having a negative power and having a concave surface or a flat surface on the object side and in a vicinity of an optical axis thereof, and the imaging lens satisfies conditional expression: 0.28<|f4/f|<0.60 ??(1) where f is a focal length of the imaging lens, and f4 is a focal length of the fourth lens.

Abstract: A micro lens, from an object side to an image side, sequentially includes a stop, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, and a fourth lens having a negative refractive power. The third and fourth lenses respectively comprise at least one aspherical surface. The negative refractive power gradually decreases from the center to the periphery of the fourth lens, and the refractive power of the periphery of the fourth lens is turned to positive. The relationship of the first lens and the focal length of the micro lens of the micro lens and the relationship of the third lens and the first lens satisfy the desired requirements, thus, to reduce the total length of the micro lens, tolerance sensitivity and cost.

Abstract: An image taking lens 1 comprises a stop 2, a first lens 3 having a positive power and biconvex configuration, a second lens 4 having a negative power and having a meniscus configuration in which a concave surface is disposed to face an object, a third lens 5 having a positive power and a meniscus configuration in which a convex surface is disposed to face an image, and a fourth lens 6 having a negative power and a meniscus configuration in which a convex surface is disposed to face the object, which are arranged in this order from the object. The lenses 3 to 6 satisfy the following formulae (1) to (4), 3.00<F1/d1<10.00??(1) ?20.0<F2/d3<?10.0??(2) 50.0<?1<60.0??(3) 20.0<?2<30.0??(4) hereupon, F1: focal length of the first lens; F2: focal length of the second lens; d1: a center thickness of the first lens; d3: a center thickness of the second lens; ?1: an Abbe's number of the first lens; and ?2: an Abbe's number of the second lens.

Abstract: The present invention provides an image pickup lens for forming a light flux from a subject into an image on an image pickup element, and the image pickup lens includes, in order from an object side thereof: an aperture stop; a first lens having a positive refractive power; a second lens having a negative refractive power and comprising a concave surface facing an image side of the image pickup lens; a third lens having a positive refractive power; and a fourth lens having a negative refractive power and comprising a concave surface facing the image side. The image pickup lens satisfies the predetermined condition according to a curvature radius of the surface facing the image side on the second lens, and a focal length of the image pickup lens.

Abstract: An imaging lens is provided and has, in order from the object side, a first lens of a positive lens having a convex surface on the object side thereof; a second lens in a meniscus shape having a concave surface on an image side thereof; a third lens in a meniscus shape having a convex surface on the image side thereof; and a fourth lens of a positive or negative lens, both surfaces of the fourth lens being aspheric and the fourth lens having a concave surface on the image side and in a vicinity of an optical axis of the fourth lens. The Abbe numbers of the first and second lenses as well as the focal distances of the first to fourth lenses satisfies specific conditions.

Abstract: A hybrid lens system includes: a first lens with positive diffractive power, a second lens with negative diffractive power, a third lens with positive diffractive power, and a fourth lens with negative diffractive power. The first lens, the second lens, the third lens and the fourth lens are aligned in that order from an object side to an image side. The first lens is made from a glass material, each of the second lens, the third lens and the fourth lens is made from a plastic material. All of the four lenses are aspheric lenses.

Abstract: Disclosed is a miniature optical system. The miniature optical system includes a first lens; a second lens; a third lens; and a fourth lens, wherein the first to fourth lenses are sequentially aligned from an object side to an image side of the system. The lenses satisfy the following equation: ?1.5<f2/ttl<?0.5, where f2 is the focal length of the second lens and ttl is a distance from an object side of the first lens to an image side of the system.

Abstract: An imaging lens is provided and includes: a first lens of a positive lens; a second lens of a negative lens whose concave surface faces to an image side of the second lens; a third lens of a positive lens, whose both surfaces are aspheric, having a concave surface facing to an object side of the third lens; and a fourth lens of a meniscus lens, whose both surfaces are aspheric, having a convex surface facing to the object side near the optical axis, the lenses being arranged in this order from an object side, the first imaging lens satisfying the conditional expressions specified in the specification.

Abstract: A focus adjustable optical system includes a first lens unit and a second lens unit arranged on an optical axis in direction from the object side to the image side. The two opposite surfaces of each of the lenses of the first lens unit and second lens unit are non-spherical surfaces. Each lens of the first lens unit defines with the image side a fixed distance. The second lens unit has one lens movable by a low-power small-sized driving source along the optical axis to adjust its distance relative to the image side and to further adjust the focal distance while the distance between the first lens unit and the image plane remains unchanged.

Abstract: A image pick-up lens system includes: a first lens with positive diffractive power, a second lens with negative diffractive power, a third lens with positive diffractive power, and a fourth lens with negative diffractive power. The first lens, the second lens, the third lens and the fourth lens are aligned in that order from an object side to an image side, and each of the four lenses is an aspheric lens made from a plastic material.