Abstract: A lens unit includes: an imaging optical system; and a lens barrel holding the imaging optical system. The imaging optical system includes, in order from an object side: a first lens having a positive refractive power; a second lens including at least one surface having an aspherical shape; and a third lens having a negative refractive power, at least one surface having an aspherical shape, and an inflection point other than an intersection with an optical axis.

Abstract: A lens unit includes: an imaging optical system; and a lens barrel holding the imaging optical system. The imaging optical system includes, in order from an object side: a first lens having a positive refractive power; a second lens including at least one surface having an aspherical shape; and a third lens having a negative refractive power, at least one surface having an aspherical shape, and an inflection point other than an intersection with an optical axis.

Abstract: An imaging optical system, an imaging device, and a digital apparatus of the invention are provided with an optical system constituted of five lens elements having positive, negative, positive, positive, and negative refractive powers, or positive, negative, negative, positive, and negative refractive powers; and satisfy the conditional expressions: 1<f123/f<1.25 0.1<d6/f<0.15 0.30<f4/f<0.72 where f: a focal length of the entirety of the imaging optical system, f123: a combined focal length of the first lens element 11, the second lens element 12, and the third lens element 13, d6: a distance on the optical axis between the third lens element 13 and the fourth lens element 14, and f4: a focal length of the fourth lens element 14.

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 single-focal-length imaging lens system achieves focusing by, while keeping first and third lens groups stationary relative to the image plane, moving a second lens group along the optical axis. The second lens group includes a positive lens element. The third lens group includes an aspherically shaped lens element having an inflection point at a position other than the intersection with the optical axis. The first and second air lenses formed by the intervals between the first and second and between the second and third lens groups have negative and positive refractive powers respectively. The conditional formula 0?|Fi1/Fi2|?|Fm1/Fm2|?10 is fulfilled (Fi1 and Fi2 representing the focal lengths of the first and second air lenses, respectively, when focusing on the infinite object distance; Fm1 and Fm2 representing the focal lengths of the first and second air lenses, respectively, when focusing on the closest object distance).

Abstract: An imaging optical system, an imaging device, and a digital apparatus of the invention are provided with an optical system constituted of five lens elements having positive, negative, positive, positive, and negative refractive powers, or positive, negative, negative, positive, and negative refractive powers; and satisfy the conditional expressions: 1<f123/f<1.25 0.1<d6/f<0.15 0.30<f4/f<0.72 where f: a focal length of the entirety of the imaging optical system, f123: a combined focal length of the first lens element 11, the second lens element 12, and the third lens element 13, d6: a distance on the optical axis between the third lens element 13 and the fourth lens element 14, and f4: a focal length of the fourth lens element 14.

Abstract: An imaging optical system, an imaging device, and a digital apparatus have a four lens construction with positive, negative, positive, and negative refractive powers. A surface position at the maximum effective diameter of the second lens element is located on the object side than a surface vertex thereof. The fourth lens element has an inflection point at a position other than the intersection of the optical axis and the fourth lens element. The optical system satisfies the following conditions. 0.7<f1/f<5 ?0.8<(RS1+RS2)/(RS1?RS2)<3 ?3<(RS3+RS4)/(RS3?RS4)<2 0.03<d2/TL<0.2 2W>72 ?4>50, and 0.55<Y/TL<0.

Abstract: Provided is an image pickup lens that forms an image on an image pickup element with light from a subject. In the image pickup lens, a lens that is disposed on an image pickup element side is fixed in position, and a focusing lens group having a plurality of lenses including a lens closest to the subject is moved in an optical axis direction, thereby performing focusing.

Abstract: Provided is a single-focus optical system which is configured, in order from the object side to the image side, of a first to third lens groups and in which the first lens group and the third lens group are fixed with respect to a predetermined imaging surface, and the second lens group is moved in the optical axis direction to focus, wherein the first lens group comprises at least one positive lens and at least one negative lens, the second lens group comprises at least one positive lens, the third lens group comprises at least one lens having at least one aspheric surface and having a positive optical power at a peripheral portion thereof and 5<|?v1|<70 is satisfied where ?v1 is a maximum value of the Abbe number difference between the positive lens and the negative lens in the first lens group.

Abstract: The present invention provides a wide-angle optical system constituted of, in order from the object side to the image side, front group 11, stop 12, and rear group 13. The front group 11 is constituted, in order from the object side to the image side, of first lens 111 having negative optical power, second lens 112 having negative optical power, and third lens 113 having positive optical power. The rear group 13 is constituted, in order from the object side to the image side, of fourth lens 131 having positive optical power, and fifth lens 132 having negative optical power. The opposite surface from the stop of each of the paired lenses 113 and 131 arranged at the both sides of the stop 12 is a convex surface.

Abstract: An imaging optical system, an imaging device, and a digital apparatus have a four lens construction with positive, negative, positive, and negative refractive powers. A surface position at the maximum effective diameter of the second lens element is located on the object side than a surface vertex thereof. The fourth lens element has an inflection point at a position other than the intersection of the optical axis and the fourth lens element. The optical system satisfies the following conditions. 0.7<f1/f<5 ?0.8<(RS1+RS2)/(RS1?RS2)<3 ?3<(RS3+RS4)/(RS3?RS4)<2 0.03<d2/TL<0.2 2W>72 ?4>50,and 0.55<Y/TL<0.

Abstract: An image pickup lens comprises a first lens (L1) having a positive refractive power, an aperture stop (s3), a second lens (L2) having a negative refractive power and having a concave surface facing the image side, a third lens (L3) having a positive refractive power, and a fourth lens (L4) having a negative refractive power and having a concave surface facing the image side. The image pickup lens satisfies predetermined formulae.

Abstract: A wide-angle optical system comprises a front lens group (11), and a rear lens group (12), with an aperture stop (13) interposed between. The front lens group (11) includes at least two negative lenses (111, 112) and at least one positive lens (113). At least one of the positive lenses included in the front lens group (11) has at least one aspherical surface. The front lens group (11) satisfies the conditional expression vdp<29 where vdp is the minimum value of the Abbe number of the positive lens(es) included in the front lens group (11).

Abstract: Provided are a wide angle optical system having better optical performance, low in cost, and compact in size, an imaging lens device having the wide angle optical system, a monitor camera, and a digital apparatus. The wide angle optical system (1) has, in order from the object side to the image side, a first lens (11) having a negative optical power, a second lens (12) having a negative optical power, a third lens (13) having a positive optical power, an aperture (15), and a fourth lens (14) having a positive optical power. The wide angle optical system satisfies the conditional expression of 3<f34/f<10, where f34 is the composite focal length of the third and fourth lenses (13, 14) and f is the focal length of the entire system.

Abstract: An imaging lens (LN) of an imaging device (ID) is composed of an aperture stop (ST) and a lens unit (LU) having positive power. Even when the object side surface of the lens unit (LU) has a shape convexed to the side of the object, and a lens whose image side surface is concaved to the image side is used, excellent aberration performance with a short optical total length, a small sensor incidence angle and a small distortion are achieved at low cost.

Abstract: A lens unit LU in which a lens portion L is formed at least on either a light-receiving surface or a light-emitting surface of a lens holding plate P, wherein a difference in coefficients of linear expansion of the lens holding plate P and the lens portion L is used to suppress mis-focusing by causing changes in a paraxial image point position of the entire lens system due to changes in the surface shape of the lens portion L which accompany temperature changes, and changes in the paraxial image point position of the entire lens system due to changes in the refraction index to cancel each other out. Furthermore, deterioration of performance of the entire lens system caused by rising temperature is suppressed by satisfying a predetermined conditional expression.

Abstract: Provided are a wafer scale lens, which is so short in an optical total length with respect to an image height that it can correct an aberration satisfactory, and an optical system including the wafer scale lens and having a thin lens element on the side closest to the image. The optical system includes a first lens having a positive refractive power relative to an object, and a second lens arranged on the side of the image of the first lens and having a recessed shape on the side of the object. At least one lens is arranged on the side of the second lens.

Abstract: An imaging lens (LN) includes at least one lens block (BK), and an aperture stop (ape). The lens block (BK) includes parallel flat lens substrates (LS) formed of different materials, and a lens (L). In the imaging lens (LN), a first lens block (BK1) positioned closest to an object includes a first lens substrate (LS1) and a lens (L[LS1o], and a prescribed conditional expression is satisfied.

Abstract: A variable magnification optical system of the present invention and an image pickup device and a digital apparatus including this are provided with a four-component optical system of negative-negative-positive-negative arrangement, wherein a first lens group thereof includes only one negative lens as a lens having an optical power, and a third lens group thereof satisfies a conditional expression of 1.4<?3t/?3w<4 when ?3t and ?3w respectively denote image magnifications of the third lens group at a telephoto end and at a wide-angle end. The variable magnification optical system, the image pickup device and the digital apparatus having such a construction can be further downsized.

Abstract: An imaging lens (LN) includes at least one lens block (BK), and an aperture stop (ape). The lens block (BK) includes a plane-parallel lens substrate (LS) and a lens (L) formed of different materials. In the imaging lens (LN), a first lens block (BK1) disposed at the most object-side exerts a positive optical power, and said at least one lens block is contiguous only with one of the object-side and image-side substrate surfaces of the lens substrate (LS).