Ask about photography. The landscape photos of ordinary people, the characters are very clear, and the scenery behind them is a bit blurred. How was this photo taken or post-processed?

Depth of field is the range of good focus. It can decide whether to blur the background to highlight the subject or shoot a clear background.

Objects are as clear as the background, which is called the depth of the scene.

The object is clear and the background is blurred, which is called the depth of the scene.

The easiest way to adjust the depth of field is to change the aperture size. If you make the aperture bigger, the depth of field will be shallower, and vice versa. Of course, the larger the aperture, the faster the shutter speed, the smaller the aperture and the slower the shutter speed. In this way, under the same exposure intensity, photos with different depth of field can be obtained.

Aperture is not the only factor that affects the depth of field. Short shooting distance leads to the depth of the scene, long shooting distance leads to the depth of the scene, and short shooting distance leads to the opposite. Therefore, when shooting with a wide-angle lens, it is easy to focus on the whole image, while when shooting with a telephoto lens, attention should be paid because the depth of field is shallow. Similarly, based on the point with good focus, the point near it is deeper than the far point.

Aperture number, also called f number. The illumination of the image (imaged on the photosensitive element) is not only related to the brightness of the scene itself and the magnification of the image, but also proportional to the square of the lens aperture diameter d. It is inversely proportional to the focal length f of the lens, and the value of D/F is called the "relative aperture" of the lens. For convenience, the reciprocal of the relative light-transmitting aperture is f/d, and the smaller the ratio, the larger the aperture and the greater the light-transmitting amount per unit time.