What are the common expressions of photographic lens?

Focal length refers to the distance from the focal point to the center of the lens. When the focal length is long, it is called a telescopic lens, which is often called a telephoto lens, and when the focal length is short, it is called a wide-angle lens, which is also called a short-focus lens.

Second, the range of view.

The framing range is a narrow shooting range, which is determined by the focal length. If the pictures are the same size, the shorter the focal length, the wider the picture will be, and the longer the focal length, the narrower the picture will be.

Third, the fixed-focus lens

Fixed focus lens literally means a lens with only one focal length. Unlike a zoom lens, the focal length cannot be adjusted, so its visual range is fixed.

Fourth, zoom lens.

Zoom lens is a kind of lens with adjustable focal length. As long as a lens can change a lot of focal length, of course, it is within the adjustable range, so zoom lens is very convenient.