Why is the camera gap so big?

Maybe you have a wrong understanding of the depth of field and its formation, or you have made an unequal comparison.

Video recording records multi-frame images by changing the aperture or focal length, and multi-frame playback shows you a changing process. The camera takes a photo, and a photo has only one focus. If it's all filmed, it's a waste film.

The focal length is long and the aperture is deep. Different lenses will bring different depth of field. In addition to the focal length and aperture, there is also the distance from the focal point and the frame (blur is due to the fact that the diffusion circle gradually expands to be recognizable by the naked eye, and the diffusion circle gradually expands outward from the focal point, and the farther it is, the more virtual it is, so the frame also has an impact on the depth of field). Under the conditions of the same focal length, the same level of aperture and the same distance from the subject, the camera is often not as deep as the camera scene because of its small frame.

(The following pictures are all from the Internet)

Format (professional cameras generally use 2/3 format to Quan Huafu, professional digital cameras generally use APS format to medium format, and film cameras use Quan Huafu to large format. Quan Huafu is equivalent to 135 film, medium format is equivalent to 120 film, and the film area larger than 120 is called large format. The largest format is larger than the CT film you saw in the hospital. At present, digital photographic equipment is the largest medium format, and the large format only has film);

Depth of field:

Feel the depth of field of 50 focal length 1.2 large aperture (image from the network)

Feel the macro depth of field (picture from the network)

Feel the depth of field of 800mm super telephoto (picture from the network)