A lens system (10) for image pickup includes, in order from an object side (11), a first lens group (G1) that has negative refractive power and is fixed during focusing, a second lens group (G2) that has positive refractive power and moves during focusing, a third lens group (G3) that has positive refractive power and is fixed during focusing, and a fourth lens group (G4) that has a stop disposed on the object side, is disposed closest to an image plane side, has positive refractive power, and is fixed during focusing. The first lens group includes a first lens (L11) with positive refractive power that is disposed closest to the object side.

A folded camera that includes two light folding elements such as prisms and an independent lens system, located between the two prisms, which includes an aperture stop and a lens stack. The lens system may be moved on one or more axes independently of the prisms to provide autofocus and/or optical image stabilization for the camera. The shapes, materials, and arrangements of the refractive lens elements in the lens stack may be selected to capture high resolution, high quality images while providing a sufficiently long back focal length to accommodate the second prism.

A folded camera that includes two light folding elements such as prisms and an independent lens system, located between the two prisms, which includes an aperture stop and a lens stack. The lens system may be moved on one or more axes independently of the prisms to provide autofocus and/or optical image stabilization for the camera. The shapes, materials, and arrangements of the refractive lens elements in the lens stack may be selected to capture high resolution, high quality images while providing a sufficiently long back focal length to accommodate the second prism.

An optical imaging lens includes a first lens element to a fifth lens element, and each lens element has an object-side surface and an image-side surface. An optical axis region of the image-side surface of the first lens element is concave, the second lens element has negative refracting power, a periphery region of the image-side surface of the second lens element is convex, the fourth lens element has positive refracting power, and an optical axis region of the object-side surface of the fifth lens element is convex. Lens elements included by the optical imaging lens are only the five lens elements described above, and the optical imaging lens satisfies the relationship of TTL/Fno≥6.000 mm, TTL is the distance from the object-side surface of the first lens element to an image plane along the optical axis, and Fno is a f-number of the optical imaging lens.

An optical imaging lens, in order from an object side to an image side along an optical axis, includes a first lens, a second lens, an aperture, a third lens, a fourth lens, and a fifth lens. The first lens has negative refractive power. The second lens has positive refractive power. The third lens is a biconvex lens with positive refractive power. The fourth lens is a biconcave lens with negative refractive power. The fifth lens has positive refractive power. The optical imaging lens satisfies: −0.55≤f345/f12≤−0.35, wherein f12 is a focal length of a combination of the first lens and the second lens, and f345 is a focal length of a combination of the third lens, the fourth lens, and the fifth lens.

The present disclosure discloses an optical imaging system including a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens, each of which has refractive power. An object-side surface of the second lens is a convex surface, and an image-side surface thereof is a concave surface; an object-side surface of the fourth lens is a convex surface, and an image-side surface thereof is a concave surface; an object-side surface of the fifth lens is a concave surface, and an image-side surface thereof is a convex surface; and each of the third lens and the sixth lens has positive refractive power. A radius of curvature R11 of an object-side surface of the sixth lens and a radius of curvature R12 of an image-side surface of the sixth lens satisfy 0.5<R11/R12<1.5.

The invention relates to a hybrid objective with fixed focal length, which has a total of four lenses. Two lenses consist of glass and two lenses consist of plastic. The objective is suitable for use in a LID AR measurement system.

The objective lens unit includes, a front lens group having a negative refractive power, a diaphragm, and a rear lens group having a positive refractive power, in order from an object side. The front lens group includes a negative lens having a concave surface facing an image surface side, and a positive lens having a convex surface facing the object side, and the rear lens group includes a positive lens having a convex surface facing the image surface side and a cemented lens in which a positive lens and a negative lens are cemented. The endoscope objective lens unit satisfies −1.6<f.sub.F/f.sub.R<−1.2 and −1.0<SF.sub.5<−0.5. f.sub.F and f.sub.R are the focal lengths of the front lens group and the rear lens group, SF.sub.5 is (R.sub.51+R.sub.52)/(R.sub.51−R.sub.52), and R.sub.51 and R.sub.52 are respectively the curvature radiuses of surfaces.

The objective lens unit includes, a front lens group having a negative refractive power, a diaphragm, and a rear lens group having a positive refractive power, in order from an object side. The front lens group includes a negative lens having a concave surface facing an image surface side, and a positive lens having a convex surface facing the object side, and the rear lens group includes a positive lens having a convex surface facing the image surface side and a cemented lens in which a positive lens and a negative lens are cemented. The endoscope objective lens unit satisfies −1.6<f.sub.F/f.sub.R<−1.2 and −1.0<SF.sub.5<−0.5. f.sub.F and f.sub.R are the focal lengths of the front lens group and the rear lens group, SF.sub.5 is (R.sub.51+R.sub.52)/(R.sub.51−R.sub.52), and R.sub.51 and R.sub.52 are respectively the curvature radiuses of surfaces.

Provided is a wide-angle lens assembly including, in an order from an object side to an image side along an optical axis, a first lens element with negative refractive power, having an image-side surface being concave; a second lens element with negative refractive power, having an image-side surface being concave; a third lens element with negative refractive power; a fourth lens element with positive refractive power; a fifth lens element with a refractive power; a sixth lens element with positive refractive power, having an object-side surface being convex and an image-side surface being convex; a seventh lens element with negative refractive power; and an eighth lens element with positive refractive power, having an object-side surface being convex and an image-side surface being convex. The wide-angle lens assembly is characterized by small size, excellent resolution and great environmental tolerance.