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.

A method for designing an optical system for providing reliable, robust and successful realization of a distortion variation function is presented. In a preferred embodiment, the proposed distortion variation optical system includes at least two non-symmetrical elements, which are moving in the transverse direction. The proposed freeform lens contains two transmissive refractive surfaces. The freeform elements designed with this method have preferably a flat surface and a non-symmetrical freeform surface. The two plano-surfaces are preferably made to face each other, so that a miniature camera can be offered. The value of the non-symmetrical freeform surface is used to produce variable optical power when the two freeform elements undergo a relative movement in the vertical direction. Using this method, an optical system with an active distortion, smaller form factor, and better imaging quality can be obtained.

A photographing optical lens assembly includes six lens elements which are, in order from an object side to an image side: a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The second lens element has positive refractive power. The third lens element has negative refractive power. The sixth lens element with negative refractive power has an image-side surface being concave in a paraxial region thereof, wherein the image-side surface of the sixth lens element has at least one inflection point.

According to an embodiment, a projection optical system for an image projection device, that includes a plurality of lenses. The projection optical system satisfies conditional expression (1): where fw is a focal length of a lens having the weakest refractive power in the lenses and f is a focal length of the whole projection optical system. $\begin{array}{cc}0.01\le .Math.\frac{f}{f_w}.Math.<0.34& \left(1\right)\end{array}$

An optical lens is provided with three lens pieces. The optical lens includes a diaphragm, a first lens piece having positive focal power, a second lens piece having negative focal power and a third lens piece having positive focal power, arranged in sequence. The first lens piece has an S1 surface and an S2 surface. The second lens piece has an S3 surface and an S4 surface. The third lens piece has an S5 surface and an S6 surface. An S7 surface is provided on a side of the S6 surface away from the S5 surface. A lens frame is provided at the S6 surface or between the S6 and S7 surfaces. The calibers of the Si to S7 surfaces sequentially decrease. An equivalent focal length of the first lens piece is larger than that of the third lens piece. A numerical aperture of the lens is larger than 0.6.

An optical imaging system includes a first lens, as second lens, a third lens, a fourth lens, and a fifth lens. The first lens includes a positive refractive power and a convex image-side surface. The second lens includes a positive refractive power, and the third lens includes a negative refractive power. The fourth lens includes a positive refractive power, and the fifth lens includes a positive refractive power. The first to fifth lenses are sequentially disposed from an object side toward an imaging plane.

A lens system includes sequentially from an object side: a first lens group having a positive refractive power; an aperture diaphragm; a second lens group having a positive refractive power; and a third lens group having a positive refractive power and moving along a direction of an optical axis when focusing from an object at infinity to a close object. Assuming that L is a distance from a lens surface of the first lens group closest to the object side to a lens surface closest to an image side on the optical axis, Y is a maximum image height, f1 is a focal length of the first lens group, and f is a focal length of the entire lens system, the lens system satisfies the following conditions: 1.0<L/Y<2.3, and 1<f1/f<3.

An image capturing lens system includes three lens groups including five lens elements. The three lens groups are, in order from an object side to an image side: first, second and third lens groups. The five lens elements are, in order from the object side to the image side: first, second, third, fourth and fifth lens elements. The first lens element has an object-side surface being convex in a paraxial region thereof. The second lens element has negative refractive power. At least one lens element has an inflection point. A focal length of the image capturing lens system is varied by changing axial distances between the three lens groups in a zooming process. The image capturing lens system has a long-focal-length end and a short-focal-length end. The second lens group is moved relative to the first lens group along an optical axis in the zooming process.

An optical lens assembly is provided. The optical lens assembly includes first, second, third and fourth lens elements having refracting power arranged along an optical axis in a sequence from a light output side to a light input side. The first lens element is arranged to be a lens element in a fourth order from the light input side to the light output side. The second lens element is arranged to be a lens element in a third order from the light input side to the light output side. The third lens element is arranged to be a lens element in a second order from the light input side to the light output side. The fourth lens element is arranged to be a lens element in a first order from the light input side to the light output side.

An optical imaging lens includes first, second, third, fourth, fifth, and sixth lens elements sequentially along an optical axis from an object side to an image side. Each of the first to the sixth lens elements includes an object-side surface facing the object side and allowing imaging rays to pass through and an image-side surface facing the image side and allowing the imaging rays to pass through. The optical imaging lens satisfies conditions of Gallmax/Fno≥3.600 millimeters, EFL/ImgH≥3.200, and Gallmax/Tavg≥3.300; here, Gallmax represents a largest air gap along the optical axis between the first lens element and an image plane, Fno, EFL, and ImgH respectively represent an F-number, an effective focal length, and an image height of the optical imaging lens, and Tavg represents an average lens element thickness of all of the lens elements along the optical axis from the object side to the image plane.