Standard focal length; relationship between focal length and depth of field

Focal Length: the distance from a point in focus of a parallel light that is reflected by the lens to the center of the plane in which the lens is located. The length of focal length determines the lens angle of view, which is the same as the distance from the camera to the subject,Field of viewLarge, shooting range (photo field)WIDE; small angle of view, small Shooting Range

The length of the focal length. Lenses are generally divided:   Standard: Equivalent35mmCamera (same below) Of 50mm , The coverage cannot exceed 40-70mm ;   Zoo: 70-150mm ; Telephoto 150-500 ;   Wang Yuan: 500 Above;   Wide angle: 40mm Below; lower 18mm The fish eye lens. The focal length is inversely proportional to the width of the shot image.   Most importantly
  When the angle of the standard lens is close to that of the human eye, the captured image conforms to the visual habits and will not cause deformation of the image.-----It looks most comfortable. Therefore, use standard lenses whenever possible.

 

 

 

Relationship between focal length and depth of field
1. "The larger the focal length, the smaller the depth, and the smaller the focal length, the larger the depth of the field" is correct.
2. "The larger the aperture, the smaller the depth, and the smaller the aperture, the larger the depth of field ."
3. "(in portrait mode) in order to further enhance the light depth of field effect, the camera and the shooting object should be kept at a distance. It is best to zoom in and zoom in to bring the target shooting closer ." Correct.

In general, it is preferred to get a small depth of depth through the "telephoto" (Open object distance. If you want to get a small depth of field through the aperture, You have to enlarge the aperture, but this amplification can be done only when the main exposure is no problem, there are restrictions. Specifically, the "aperture" and "Shutter" are used to adjust the incoming light volume.