Can the folding lens focus automatically?

The foldback lens can focus automatically.

A catadioptric lens is a lens that uses a concave mirror at the end of the lens barrel, which is closest to the camera. After the light reaches the paraboloid of the reflector, it is reflected to its focus, and then reflected to the camera through a small reflector. The reflected image passes through the circular hole in the center of the main mirror, is further focused by various lens units, and then is transmitted to the camera.

brief introduction

Catadioptric lens, also called reflex lens, is a special form of telephoto lens. When the light passes through the lens, it enters from the first group of lenses and reaches the film directly.

The lens uses non-dispersive reflecting surface instead of dispersive refracting surface, and the dispersion is well controlled. There is a reflective surface in the center of the optical path, so there is only one aperture value. Because the light passing through the lens is annular, the defocused speckle is simple in structure and low in price.

It is even more inconvenient to change the aperture. It is a very effective creative method to control the depth of field by changing the aperture in photography, but for the reflector, it is impossible to control the depth of field because the aperture cannot be changed.