Abstract: There is provided a compact imaging lens configured to properly correct aberrations. The imaging lens includes, in order from an object side to an image side, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with positive refractive power, a fifth lens L5, a sixth lens L6, a seventh lens L7 with positive refractive power, and an eighth lens L8 with negative refractive power. The eighth lens L8 is formed in a shape of a meniscus lens in a paraxial region, and has an aspheric image-side surface having at least one inflection point. In addition, the following conditional expressions are satisfied: ?5.00<f2/f<?2.00 10.00<f4/f<25.00 where f: a focal length of the overall optical system of the imaging lens, f2: a focal length of the second lens, and f4: a focal length of the fourth lens.

Abstract: An imaging lens includes a first lens having positive refractive power; a second lens having negative refractive power; a third lens having negative refractive power; a fourth lens having negative refractive power; a fifth lens; a sixth lens; a seventh lens; an eighth lens; and a ninth lens having negative refractive power, arranged in this order from an object side to an image plane side. The ninth lens is formed in a shape so that a surface thereof on the image plane side has an aspherical shape having an inflection point.

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; a sixth lens; a seventh lens; an eighth lens; and a ninth lens having negative refractive power, arranged in this order from an object side to an image plane side. The ninth lens is formed in a shape so that a surface thereof on the image plane side has an aspherical shape having an inflection point.

Abstract: An imaging lens includes a first lens; a second lens; a third lens having negative refractive power; a fourth lens; a fifth lens; a sixth lens; and a seventh lens, arranged in this order from an object side to an image plane side. The sixth lens is formed in a shape so that a surface thereof on the image plane side is concave at a paraxial region thereof. The seventh lens is formed in a shape so that a surface thereof on the image plane side is aspheric. The first lens and the second lens have a specific composite focal length. The third lens have a specific focal length.

Abstract: An imaging lens includes a first lens; a second lens; a third lens having negative refractive power; a fourth lens having positive refractive power; a fifth lens; a sixth lens; and a seventh lens, arranged in this order from an object side to an image plane side. The first lens has at least one aspheric surface. The fifth lens has two aspheric surfaces. The sixth lens is formed in a shape so that a surface thereof on the object side is convex at a paraxial region thereof and a surface thereof on the image plane side is concave at a paraxial region thereof. The seventh lens has two aspheric surfaces.

Abstract: A projection system includes a first optical system and a second optical system sequentially arranged from a reduction side toward an enlargement side. The second optical system includes an optical element having a concave reflection surface and a first lens having negative power, the optical element and the first lens sequentially arranged from the reduction side toward the enlargement side. The projection system satisfies Conditional Expressions (1) and (2) below. 3.5 ? LL + MR / imy × TR × 1 / NA ? 6.0 ­­­(1) TR ? 0 .

Abstract: A projection system includes a first lens group, an aperture diaphragm, and a second lens group. A reduction side of the second lens group is telecentric. The first lens group includes a first sub-lens group having negative power and a second sub-lens group having positive power. Between a lens located at the most reduction side of the first sub-lens group and a lens located at the most enlargement side of the second sub-lens group, an air gap wider than air gaps between the other lenses adjacent to each other is provided. A lens located at the most reduction side in the first lens group is a positive lens. A cemented lens of the second lens group includes a first lens having negative power, a second lens having positive power, and a third lens having negative power from an enlargement side toward a reduction side. ?>40.

Abstract: A projection system includes a first lens group having positive power, an aperture stop, and a second lens group having positive power sequentially arranged from the enlargement side toward the reduction side. The portion at the reduction side of a reduction-side lens that forms the second lens group and is located at a position closest to the reduction side is a telecentric portion. The projection system satisfies Conditional Expressions (1) and (2) below, ?>40°??(1) YL1/YIM<6.0 ??(2) where ? represents a maximum half angle of view of the overall projection system, YIM represents the distance from an optical axis to the largest image height of the projection image formed at an image formation device, and YL1 is the distance from the optical axis to a chief beam corresponding to the maximum image height in an imaginary plane.

Abstract: A projection system includes a first lens group having refractive power, an aperture stop, and a second lens group having refractive power sequentially arranged from the enlargement side toward the reduction side. The first lens group includes a first lens disposed at a position closest to the enlargement side, a second lens disposed at the reduction side of the first lens, and a plurality of positive lenses disposed at the reduction side of the second lens and each having positive power. The portion at the reduction side of a reduction-side lens that forms the second lens group and is located at a position closest to the reduction side is a telecentric portion. The projection system satisfies Conditional Expressions (1) and (2) below, Ln?gF?0.

Abstract: An imaging lens includes a first lens having positive refractive power; a second lens having negative refractive power; a third lens having negative refractive power; a fourth lens having negative refractive power; a fifth lens; a sixth lens; a seventh lens; an eighth lens; and a ninth lens having negative refractive power, arranged in this order from an object side to an image plane side. The ninth lens is formed in a shape so that a surface thereof on the image plane side has an aspherical shape having an inflection point.

Abstract: An imaging lens includes a first lens having positive refractive power; a second lens; a third lens; a fourth lens; a fifth lens; a sixth lens; a seventh lens; an eighth lens; and a ninth lens, arranged in this order from an object side to an image plane side. The imaging lens has a total of nine lenses. The eighth lens has at least one aspheric surface. The ninth lens is formed in a shape so that a surface thereof on the image plane side has an aspherical shape. The ninth lens is formed in the shape so that the surface thereof on the image plane side has a specific paraxial curvature radius.

Abstract: There is provided a compact imaging lens configured to properly correct aberrations. The imaging lens includes, in order from an object side to an image side, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with negative refractive power, a fifth lens L5, a sixth lens L6, a seventh lens L7 with positive refractive power, and an eighth lens L8 with negative refractive power. The fourth lens is formed in a shape of a meniscus lens having an object-side surface being concave in a paraxial region. The eighth lens L8 has an aspheric image-side surface having at least one inflection point. Furthermore, the following conditional expression is satisfied: 0.04<D34/f<0.15 where f: a focal length of the overall optical system of the imaging lens, and D34: a distance along the optical axis between the third lens and the fourth lens.

Abstract: There is provided a compact imaging lens configured to properly correct aberrations. The imaging lens includes, in order from an object side to an image side, a first lens L1 having negative refractive power, a second lens L2 having negative refractive power, a third lens L3 having positive refractive power, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8 having negative refractive power. The eighth lens L8 has an aspheric image-side surface having at least one inflection point.

Abstract: There is provided a compact imaging lens configured to properly correct aberrations. The imaging lens includes, in order from an object side to an image side, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with negative refractive power, a fifth lens L5, a sixth lens L6, a seventh lens L7 with positive refractive power, and an eighth lens L8 with negative refractive power. The fourth lens is formed in a shape of a meniscus lens having an object-side surface being concave in a paraxial region. The eighth lens L8 has an aspheric image-side surface having at least one inflection point. Furthermore, the following conditional expression is satisfied: 0.04<D34/f<0.15 where f: a focal length of the overall optical system of the imaging lens, and D34: a distance along the optical axis between the third lens and the fourth lens.

Abstract: An imaging lens includes a first lens; a second lens; a third lens; a fourth lens; a fifth lens; a sixth lens; a seventh lens having positive refractive power; an eighth lens; and a ninth lens, arranged in this order from an object side to an image plane side. The imaging lens has a total of nine lenses. The eighth lens is formed in a shape so that a surface thereof on the object side has an aspherical shape. The ninth lens is formed in a shape so that a surface thereof on the image plane side has an aspherical shape.

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 negative refractive power; a fifth lens; a sixth lens; a seventh lens; an eighth lens; and a ninth lens having negative refractive power, arranged in this order from an object side to an image plane side. The ninth lens is formed in a shape so that a surface thereof on the image plane side has an aspherical shape having an inflection point.

Abstract: An imaging lens includes a first lens having positive refractive power; a second lens; a third lens; a fourth lens; a fifth lens; and a sixth lens, arranged in this order from an object side to an image plane side with spaces in between each of the lenses. The first lens has one aspheric surface. The third lens has one aspheric surface. The fourth lens has one aspheric surface. The fifth lens has two aspheric surfaces and the surface thereof on the object side is convex toward the object side near an optical axis thereof. The sixth lens has two aspheric surfaces and the surface thereof on the image plane side is convex toward the image plane side near an optical axis thereof. The second lens and the third lens have a specific focal length. The second lens and the fifth lens have a specific Abbe's number.

Abstract: An imaging lens includes a first lens; a second lens; a third lens having negative refractive power; a fourth lens; a fifth lens; a sixth lens; and a seventh lens, arranged in this order from an object side to an image plane side. The first lens is formed in a meniscus shape at a paraxial region thereof. The sixth lens is formed in a shape so that a surface thereof on the object side is convex at a paraxial region thereof. The fourth lens and the fifth lens have a specific composite focal length. The sixth lens and the seventh lens have a specific composite focal length.

Abstract: An imaging lens includes a first lens; a second lens; a third lens; a fourth lens; a fifth lens; a sixth lens; and a seventh lens, arranged in this order from an object side to an image plane side. The sixth lens is formed in a shape so that a surface thereof on the image plane side is concave at a paraxial region thereof. The seventh lens is formed in a shape so that a surface thereof on the image plane side is aspheric. The first lens and the second lens have a specific composite focal length. The third lens have a specific focal length. The fourth lens and the fifth lens have a specific composite focal length. The sixth lens and the seventh lens have a specific composite focal length.

Abstract: A projection system includes first lens group having negative power and second lens group having positive power sequentially arranged from enlargement side toward reduction side. first lens group includes first-a lens group having negative power, first-b lens group located at reduction side of first-a lens group and having negative power, and first-c lens group located at reduction side of first-b lens group and having positive power. Sum of number of lenses of first-a lens group and number of lenses of first-b lens group is smaller than or equal to three. Projection system satisfies each of Conditional Expressions (1) and (2) below, BF/F>5.0??(1) 0.3<|F/F1ab|<1.0??(2) where F represents the focal length of the overall projection system, BF represents the back focal length in air, and F1ab represents the combined focal length of the first-a lens group and the first-b lens group.