Do focusing and focusing mean the same thing?

If you are reading books or articles related to photography, these two words have the same meaning.

(1) focusing is a design concept of optical lens. The so-called focusing, according to Baidu Encyclopedia, is "the process of controlling a beam of light or particle flow to converge to a point as much as possible, and focusing is a necessary condition for imaging". Conceptually speaking, focusing is the process of lens acting on light. Whether the focal length of your optical lens has changed or not, if you want to image, you must first ensure that you can focus. In other words, only an optical system that can focus is an optical system that can image. In principle, all the cameras we get can image, so they can focus. As far as the correlation between the three is concerned, if we want to focus or focus, we must first ensure that the optical system itself is focused.

(2) Focusing refers to the process of changing the object distance and the position of the distance through the camera focusing mechanism without changing the focal length of the optical system, so as to make the image of the object clear. This concept is an active adjustment process of the camera for clear imaging. What is the adjustment? Not the focal length, but the object distance and distance position. 1/f =1/u+1/v, focusing is to keep f (focal length) unchanged and adjust the values of u (object distance) and v (image distance) to make the formula hold. Why do you need this focusing process? It's easy to understand: whether it's shooting a landscape or a room, the scenery is layered, some are far and some are near. Because the depth of field of the imaging system is limited, if you want to shoot far, the near one will be burnt, and if you want to shoot close, the far one will blur the background. So you need to aim at the position you are interested in by focusing and adjust the camera to make the image clear. As far as the correlation between the three is concerned, firstly, the optical system focuses, and then, because the position where it focuses on imaging is not the position you want, you need to take focusing action to make your optical system focus on the position you want.