What is the viewpoint of the lens? What are these three kinds of lenses?

I don't know whether you mean TV camera or photo photography.

In photo photography: the viewpoint is the visual focus, that is, the place that makes people feel eye-catching. There can only be one viewpoint on the picture of a photo, which is called the center of the picture. The choice of viewpoint plays an important role in highlighting the theme and enhancing the appeal of photos.

In fact, photo photography can be divided into five categories according to the focal length of the lens:

Standard lens (135 film focal length is about 50mm, 120 film focal length is about 80mm).

Wide-angle lens (wide-angle lens with focal length of 35mm-24mm and ultra-wide-angle lens with focal length of 20mm- 15mm).

Medium focal length lens (focal length: 100mm- 150mm)

Telephoto lens (telephoto lens with a focal length of about 200mm and ultra telephoto lens with a focal length of more than 300mm)

Fisheye lens (focal length between 6 mm and 8 mm)