What is defocusing?

Out-of-focus phenomenon refers to the fuzzy feeling caused by the fact that the focus is not on the shooting object. If the photographer's focusing operation is fine but still out of focus, it is that the lens is out of focus.

Of course, some people deliberately use this defocusing technique in their photographic creation, which makes the whole picture blurred. For example, at night, you shoot a street lamp with a large aperture and deliberately lose focus, so that the whole picture is a colorful aperture. When using this technology on the autofocus lens, you should focus manually, otherwise the camera will focus on an object automatically.

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. The optical system with short focal length has better focusing ability than the optical system with long focal length.

Extended data:

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 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 the light beam parallel to the main axis of the convex lens passes through the convex lens;

On the other side of the convex lens, it will be converged into a point 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.