Why is the longer the focal length, the farther the shooting distance?

The longer the focal length, the closer the shooting distance, the brighter the aperture and the stronger the blur effect.

Background blur is a popular and frequently used phenomenon in photography, which is closely related to the focal length of the lens used, the brightness (aperture value) of the aperture and the shooting distance (the distance from the camera to the subject). The longer the focal length is, the easier it is to blur the background when the aperture value of the lens is constant. Of course, if the focal length is the same, the brighter the aperture, the easier it is to produce blur effect.

Extended data:

When the camera lens is adjusted to infinity, it is actually a nominal focal length. In design, the distance between the main plane of the lens and the negative or imaging sensor is adjusted to the length of the focal length, and then the image far away from the lens can form a clear image on the negative or sensor.

When the lens wants to shoot a close object, the actual focal length of the lens changes. The focal length is usually marked in millimeters (mm), but you can still see that some old lenses are marked in centimeters (cm) or English. The size of the field of view depends on the ratio of lens focal length to film size.

Because the most popular specification now is 35mm, the field of view of the lens is often marked according to this specification. The fields of view of standard lens (50mm), wide-angle lens (24mm) and telescope head (500mm) are different. The same is true for digital cameras, whose photoreceptors are smaller than the traditional 35mm film, so they can get the same image with a shorter focal length.

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