An optical lens includes a first lens group, a second lens group and an aperture stop disposed between the first lens group and the second lens group. The optical lens satisfies the conditions of 7 mm<D<25 mm and 0.3<D/LT<0.5, where D is a diameter of a lens surface of the second lens group furthest from the first lens group and LT is a total lens length measured along an optical axis between a lens surface of the first lens group furthest from the second lens group and the lens surface of the second lens group furthest from the first lens group.

An optical imaging system includes a first lens having refractive power; a second lens having refractive power; a third lens having refractive power and cemented to the second lens; a fourth lens having refractive power; a fifth lens having refractive power and cemented to the fourth lens; a sixth lens having refractive power; a seventh lens having refractive power; and an eighth lens having refractive power. The first to eighth lenses are sequentially disposed in numerical order beginning with the first lens from an object side of the optical imaging system toward an imaging plane of the optical imaging system.

An optical system includes, in order from object side to image side, a negative front lens unit, an aperture stop, and a positive rear lens unit. The front lens unit consists of, in order from object side to image side, a negative first lens having a concave surface on image side, a negative second lens with a concave surface on image side, and a positive third lens. The rear lens unit consists of, in order from object side to image side, a positive fourth lens, and a cemented lens formed by cementing a positive lens and a negative lens together. Here, a distance on optical axis from a lens surface on object side of the first lens to a lens surface on image side of the third lens, a focal length of the third lens, and a focal length of the optical system are set to appropriate values.

An illustrative example camera assembly includes a sensor. An infrared cut filter is situated to filter radiation as the radiation approaches the sensor. A plurality of lens elements is situated between the sensor and the infrared cut filter.

A projection lens includes a DMD chip, an equivalent prism, a vibrating mirror, a first refractive lens group, a diaphragm, and a second refractive lens group that are successively arranged. The first refractive lens group includes a first lens, a triple-cemented lens, and a fifth lens that are successively arranged. The triple-cemented lens includes a second lens, a third lens, and a fourth lens, and the fourth lens is an aspherical lens.

An optical lens is provided. The optical lens includes, in order from an object side to an image-forming side, a first lens having negative refractive power, a second lens having negative refractive power, a third lens having refractive power and having an Abbe number Vd3, a cemented lens having refractive power, and a fourth lens having refractive power and having an Abbe number Vd4, wherein 15≦Vd3 and/or Vd3≦30, and 60≦Vd4 and/or Vd4≦85.

An image-space telecentric lens includes, in order from a magnified side to a minified side, a first lens group of negative refractive power, an aperture stop, and a second lens group of positive refractive power. The first lens group has at least one aspheric surface, and the second lens group has at least one aspheric surface. The second lens group has a cemented lens of positive refractive power, and the cemented lens is nearest the aperture stop as compared with other lens in the second lens group. The image-space telecentric lens satisfies the condition: TT<100 mm, where TT denotes a length measured along an optical axis and between two outermost opposite lens surfaces of the image-space telecentric lens.

An optical imaging lens set includes a first lens element with an object-side surface of a convex part in a vicinity of the optical axis, a second lens element with an image-side surface of a concave part in a vicinity of its periphery, the first lens element being glued to the second lens element to eliminate an air gap, a third lens element with an object-side surface of a concave part in a vicinity of its periphery, a fourth lens element and a fifth lens element of plastic material, ALT being the total thickness of the five lens elements and G.sub.max being the max value of the air gap from the first lens element to the fifth lens element so that ALT/G.sub.max≦2.2.

An objective optical system for endoscope includes, a first group having a positive refractive power, an aperture stop, and a second group having a positive refractive power, wherein the first group includes a first lens having a negative refractive power, and a second lens having a positive refractive power, the second group includes a cemented lens, and the cemented lens includes a third lens having a positive refractive power and a fourth lens having a negative refractive power, and the following conditional expressions (1), (2), (3), (4), (7) and (9) are satisfied:

0.13≦La/Lb≦0.17   (1),

−2.7≦f4/f≦−2.2   (2),

−0.7≦(ne2×f2)/(ne4×f4)≦0   (3),

2.5≦νd3/νd4≦3.5   (4)

−2.6≦r2o/rcc≦−2   (7), and

−1.2≦r2i/f2≦−0.9   (9).

Disclosed are an optical lens assembly and an electronic apparatus including the disclosed lens assembly. The optical lens assembly includes a first lens group having positive refractive power, an iris diaphragm, and a second lens group having positive refractive power, which are arranged from an object side to an image side of an optical axis, the object side facing an object for image capture and the image side facing an imaging surface of an image sensor. The first lens group includes a first air lens having negative refractive power and a convex surface facing the object side and a second air lens having negative refractive power and two convex surfaces. The second lens group includes a lens closest to the image side of the optical axis that has positive refractive power and a convex surface facing the image side. The closest image-side lens includes an aspherical surface. The optical lens assembly has a maximum viewing angle of 130 degrees or more.