Fish-eye lens

Abstract

The invention provides a fish-eye lens. The fish-eye lens comprises a first lens group, a second lens group and a diaphragm, wherein the first lens group is close to an object side and has negative focal power, the second lens group is close to an imaging surface and has positive focal power, and the diaphragm is arranged between the first lens group and the second lens group; the first lens group sequentially comprises a crescent moon-shaped first lens, a second lens and a third lens from the object side to the imaging surface, the crescent moon-shaped first lens has negative focal power, and a concave surface of the crescent moon-shaped first lens faces to the imaging surface; the second lens group sequentially comprises a double-convex fourth lens, a fifth lens and a crescent moon-shaped six lens from the object side to the imaging surface; the double-convex fourth lens has positive focal power, the crescent moon-shaped six lens has negative positive focal power, a convex surface of the crescent moon-shaped six lens faces to the object side, and the fifth lens and the crescent moon-shaped six lens form a lens element having positive focal power; and each lens is a glass spherical lens, and the optical centers of the lenses are located on the same straight line. The structural composition of the fish-eye lens can be miniaturized, and besides, each lens is the glass spherical lens, so that the multiplying power correction can be easily realized, and the fish-eye lens is applicable to different temperature occasions.

Description

technical field [0001] The invention relates to the technical field of camera lenses, in particular to a fisheye lens. Background technique [0002] A fisheye lens is a wide-angle lens with a very short front lens diameter and a parabolic shape that protrudes toward the front of the lens. Its focal length is extremely short and its field of view is as high as 180°. Due to its large field of view advantages, fisheye lenses are widely used in high-definition sports cameras, drone cameras, panoramic surveillance and other imaging fields. [0003] At present, with the development of optical lens technology, although the structural form of the fisheye lens has been continuously improved, the basic structure has not changed, mainly including the front group lens and the rear group lens. The front group lens is a lens with a large negative power. The meniscus lens group is used to realize the optical performance with an angle of view greater than or equal to 180°, and the rear len...

AI Technical Summary

Problems solved by technology

The fisheye lens in the prior art has a large number of lenses, resulting in a large volume of the entire fisheye lens, high cost, and difficult processing

For example, in patent CN201610290697.X, although the field of view of the fisheye lens can reach 240° and the relative aperture can reach F / 1.4, the total optical length of the entire lens is L=60.84mm, which is not conducive to the miniaturization of the entire lens, and the cost is high

[0004] In addition, in order to obtain high-resolution imaging, large wide-angle fisheye lenses must be corrected for chromatic aberration of magnification. However, in the existing technology, many fisheye lens manufacturers use many plastic aspheric lenses in fisheye lenses in order to reduce costs. However, there are few types of plastics, the correction magnification is difficult to achieve, and plastics are sensitive to temperature, so it is difficult for fisheye lenses to be suitable for high or low temperature occasions

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