Concave lens is also called negative spherical lens. The middle of the lens is thin, the edge is thick and concave, so it is also called concave lens. Concave lenses have a divergent effect on light. Myopic glasses are concave lenses.
A convex lens is made according to the refraction principle of light. A convex lens is a lens with a thick center and a thin edge. Convex lenses are divided into biconvex, plano-convex, concave-convex (or positive meniscus) and other forms. Convex lens is also called convergent lens, because it can converge light, while thicker convex lens has telescopic and convergent functions, which is related to the thickness of the lens. Hyperopia glasses are convex lenses.
Extended data:
Focal length is a measure of light convergence or divergence in an optical system, which refers to the distance from the optical center of the lens to the focal point of light convergence when parallel light is incident. It is also the distance from the center of the lens to the imaging plane such as the backplane or CCD in the camera. An optical system with a short focal length has a better ability to collect light than an optical system with a long focal length.
Focal length, also known as focal length, is a measure of light convergence or divergence in an optical system, which refers to the distance from the center of the lens to the focal point of light convergence. That is, the distance from the optical center of the lens to the imaging plane such as the backplane, CCD or CMOS in the camera. An optical system with a short focal length has a better ability to collect light than an optical system with a long focal length.
The lens of a camera is a set of lenses. When the light parallel to the main optical axis passes through the lens, the light converges to a point called the focal point, and the distance from the focal point to the center of the lens (that is, the optical center) is called the focal length.
A lens with a fixed focal length, that is, a fixed focus lens; The lens whose focal length can be adjusted and changed is a zoom lens. (When a beam of light parallel to the main axis of the convex lens passes through the convex lens, it will converge to a point on the other side of the convex lens, which is called the focal point, and the distance from the focal point to the optical center of the convex lens is called the focal length of the convex lens. There is a focal point on each side of the convex lens. )
A convex lens can image. Generally, when a convex lens is used as the lens of a camera, the clearest image formed by it will not fall on the focus, or the distance (image distance) from the clearest image to the optical center is generally not equal to the focal length, but slightly larger than the focal length. The specific distance is related to the distance between the subject and the lens (object distance). The greater the object distance, the smaller the image distance (but always greater than the focal length).
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