The English name of optical zoom is Optical Zoom，Digital video cameras rely on optical lens structures to achieve zooming. The optical lens is an essential part of the machine vision system, which directly affects the quality of the image, and affects the realization and effect of the algorithm. There are many specifications of the optical lens, which can be divided into short-focus lenses, medium-focus lenses, and telephoto lenses in terms of focal length. ; From the size of the field of view, there are wide-angle, standard, and telephoto lenses; in terms of structure, there are fixed-aperture fixed-focus lenses, manual aperture fixed-focus lenses, automatic aperture fixed-focus lenses, manual zoom lenses, automatic zoom lenses, and automatic aperture electric zoom lenses. , Motorized three-variable (aperture, focal length, focus variable) lens, etc. The optical zoom method of a digital camera is to zoom in and out of the scene to be photographed by moving the lens. The larger the optical zoom factor, the farther the scene can be photographed.
Zoom lens: Also known as telescopic lens, there are two types of manual zoom lens and electric zoom lens. Electric zoom lens refers to the use of electric motor, integrated control card, and control software to adjust the magnification of the lens , and a new type of lens that can achieve par-focus by observing the real-time images of the computer and obtain the clearest images.
                          
Variable focus lens (Vari-Focal lens): It is between the standard lens and the wide-angle lens. The focal length is continuously variable, which can magnify distant objects, and at the same time provide a wide field of view to increase the monitoring range.
                          

Optical zoom is produced by changing the positions of the lens, object and focus. When the imaging surface moves in the horizontal direction, the vision and focal length will change, and the farther scenes will become clearer.
Therefore,There must be two ways to change the angle of view. One is to change the focal length of the lens. In terms of photography, this is optical zoom. The focal length of the lens; the other is to change the size of the imaging surface, that is, the length of the diagonal of the imaging surface. In current digital photography, this is called digital zoom. In fact, digital zoom does not change the focal length of the lens, but only changes the angle of view by changing the angle of the imaging face diagonal, thus producing an effect "equivalent" to the change of the focal length of the lens.
Both the zoom lens (Vari-Focal) and the zoom lens (Zoom) have the function of adjusting the width of the field of view, but when we adjust the multiplier lens, the focal length will be adjusted accordingly, so when we Zoom+ or Zoom-, it will not There is a phenomenon of out-of-focus, but the zoom lens still needs to adjust the focal length again to make the image clear after adjusting the value.

*The Zoom of the above content isOptical Zoom，The Zoom of the above content is