Abstract: A wide angle of view optical system, suitable for monitor cameras such as an in-vehicle camera and a security camera, having a reduced optical entire length and aberration correction for forming an optical image on light-receiving surfaces of an imaging element having a first lens having a negative optical power and a group of lenses each having a positive optical power, which are serially disposed from an object side. The first lens comprises at least one aspherical surface, and has a concave surface centered around an optical axis in vicinity of the optical axis on an image-side surface thereof. Further, an optical entire length T in millimeters (mm) of the entire system, a half angle of view ?, and a focal distance ftot of the entire system, also in millimeters, satisfy the conditional expressions.

Abstract: A small high-definition variable power optical system having a variable power ratio of about two to three times; an imaging apparatus including the variable power optical system; and digital equipment mounted with the imaging apparatus are provided. The variable power optical system, consisting of a plurality of lens groups, for performing variable power by changing the distance between each lens groups in an optical axis direction is configured by two or more lens groups, each having negative or positive optical power, arranged in such order from the object side. The first lens group is a cemented lens configured by at least one negative lens and at least one positive lens arranged in order from the object side. At least one aspherical surface is arranged to each of the first lens group and the second lens group. A third lens group having a positive optical power is arranged on the image plane side of the second lens group.

Abstract: There are provided a first lens group having a negative optical power as a whole, second and third lens groups having positive optical powers as a whole, which are located in this order from the object side. These lens groups are all configured to be movable in the optical axis direction during magnification. The first lens group is constituted by a bi-concave lens having a negative optical power and a positive meniscus lens which is convex at the object side thereof, which are located in this order from the object side. The second lens group is constituted by a bi-convex lens having a positive optical power and a bi-concave power having a negative optical power, which are located in this order from the object side and bonded to each other to constitute a cemented lens. The third lens group is constituted by a bi-convex lens having a positive optical power. The first and fifth lenses are double-aspherical lenses formed from resin and the third and fourth lenses are single-aspherical lenses.

Abstract: Three or more lens groups including a negative first lens group and a positive second lens group in this order from an object side are provided. The first lens group is composed of two or more lenses. At least three lens groups are composed of single lens elements, namely, only a single lens, a cemented lens, or a lens in which adjacent lenses are integrated with each other in a fixed manner. This variable power optical system has a power ratio of about two to three, and is compact and high-definition.

Abstract: In a zoom optical system for forming an optical image of an object onto a light receiving plane of an image sensor for converting the optical image into an electrical signal, and performing zooming by varying distances between a first lens group and a second lens group, and between the second lens group and a third lens group in an optical axis direction, the zoom optical system includes: the first lens group having a negative optical power; the second lens group having a positive optical power; and the third lens group having a positive optical power, wherein the first lens group is composed of two or more lens elements including at least one positive lens element and at least one negative lens element, the second lens group is composed of two or more lens elements including at least one positive lens element and at least one negative lens element, and all the lens elements in the first lens group are made of a plastic material.

Abstract: An optical system having a wide angle of view for forming an optical image of a photographic subject on light-receiving surfaces of an imaging element that converts the optical image into an electrical signal comprises a first lens having a negative optical power and a group of lenses each having a positive optical power, which are serially disposed from an object side. The first lens comprises at least one aspherical surface, and has a concave surface centered around an optical axis in vicinity of the optical axis on an image-side surface thereof. Further, an optical entire length T (mm) of the entire system, half angle of view ?, and focal distance ftot (mm) of the entire system satisfy the following conditional expressions. 10 mm<T×sin ?<30 mm 7<T/ftot<20 Thereby, the wide-angle optical system achieving a wide angle of view, reducing the optical entire length and capable of favorably correcting an aberration can be obtained.

Abstract: A zoom optical system has lens groups, and performs zooming by varying distances between the respective lens groups in an optical axis direction thereof. The zoom optical system has two or more lens groups having a negative optical power and a positive optical power in this order from an object side. The first lens group (Gr1) and the second lens group (Gr2) each have three or less lens elements. The second lens group (Gr2) includes a positive lens element having a refractive index of 1.7 or more. The positive lens element has at least one aspherical surface. With this arrangement, provided are a compact and superfine zoom optical system with a zoom ratio of about two to three times, an imaging lens device incorporated with the zoom optical system, and a digital apparatus loaded with the imaging lens device.

Abstract: There are provided a first lens group having a negative optical power as a whole, second and third lens groups having positive optical powers as a whole, which are located in this order from the object side. These lens groups are all configured to be movable in the optical axis direction during magnification. The first lens group is constituted by a bi-concave lens having a negative optical power and a positive meniscus lens which is convex at the object side thereof, which are located in this order from the object side. The second lens group is constituted by a bi-convex lens having a positive optical power and a bi-concave power having a negative optical power, which are located in this order from the object side and bonded to each other to constitute a cemented lens. The third lens group is constituted by a bi-convex lens having a positive optical power. The first and fifth lenses are double-aspherical lenses formed from resin and the third and fourth lenses are single-aspherical lenses.

Abstract: Three or more lens groups including a negative first lens group and a positive second lens group in this order from an object side are provided. The first lens group is composed of two or more lenses. At least three lens groups are composed of single lens elements, namely, only a single lens, a cemented lens, or a lens in which adjacent lenses are integrated with each other in a fixed manner. This variable power optical system has a power ratio of about two to three, and is compact and high-definition.

Abstract: A small high]-definition variable power optical system having a variable power ratio of about two to three times; an imaging apparatus including the variable power optical system; and digital equipment mounted with the imaging apparatus are provided. The variable power optical system, consisting of a plurality of lens groups, for performing variable power by changing the distance between each lens groups in an optical axis direction is configured by two or more lens groups, each having negative or positive optical power, arranged in such order from the object side. The first lens group is a cemented lens configured by at least one negative lens and at least one positive lens arranged in order from the object side. At least one aspherical surface is arranged to each of the first lens group and the second lens group. A third lens group having a positive optical power is arranged on the image plane side of the second lens group.

Abstract: In a zoom optical system for forming an optical image of an object onto a light receiving plane of an image sensor for converting the optical image into an electrical signal, and performing zooming by varying distances between a first lens group and a second lens group, and between the second lens group and a third lens group in an optical axis direction, the zoom optical system includes: the first lens group having a negative optical power; the second lens group having a positive optical power; and the third lens group having a positive optical power, wherein the first lens group is composed of two or more lens elements including at least one positive lens element and at least one negative lens element, the second lens group is composed of two or more lens elements including at least one positive lens element and at least one negative lens element, and all the lens elements in the first lens group are made of a plastic material.

Abstract: A super-wide-angle optical system for forming an optical image of an object on an image pickup surface of an image sensing device that converts the optical image into an electrical signal is provided with, in order from the object side, a first negative lens, a second negative lens and a positive lens. The first negative lens has a meniscus shape convex to the object side. The second negative lens is positioned next to the first negative lens. The positive lens has an aspherical surface. At least one of four lens surfaces of the first and second lenses is an aspherical surface. A prescribed condition is fulfilled.

Abstract: An image-taking apparatus has an image sensor for converting an optical image into an electrical signal, and a taking lens system for forming the optical image on the light-receiving surface of the image sensor. The most object-side surface of the taking lens system is an aspherical surface that has a positive optical power in a central portion thereof and a negative optical power in a peripheral portion thereof, and the following condition is fulfilled: ?90<Da<?20, where Da represents the distortion (%) observed at the maximum half view angle in the diagonal direction of the image sensor.

Abstract: An image-taking apparatus has an image sensor for converting an optical image into an electrical signal, and a taking lens system for forming the optical image on the light-receiving surface of the image sensor. The most object-side surface of the taking lens system is an aspherical surface that has a positive optical power in a central portion thereof and a negative optical power in a peripheral portion thereof, and the following condition is fulfilled: −90<Da<−20, where Da represents the distortion (%) observed at the maximum half view angle in the diagonal direction of the image sensor.