Excuse me, the relationship between the focal length and shooting distance of a digital camera.

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.

In addition, the degree of background blur will change with the change of shooting distance. The shorter the shooting distance, the closer it is to shooting, and the greater the blur effect. Therefore, if you want to get a sharp blur effect, you should choose a lens with shorter shooting distance, brighter aperture and longer focal length.

Just determine the focal length of the lens when shooting, and then fix the shooting distance after the composition is completed. Therefore, while mastering the basic principle of blur, we also need to master the relationship between lens focal length and shooting distance.

Extended data

Focus conversion

On models with different frames, the viewing angles of the pictures taken with the same focal length are also different. When the same lens is connected to the Quan Huafu model, the photos taken have a larger viewing angle, while when it is connected to the small-format model such as APS, the photos taken have a smaller viewing angle. This effect is the same as the different viewing angles caused by the focal length of the lens.

For example, Nikon D700 comes with a lens of 17mm, which is 1.5 times the viewing angle of the picture taken when Nikon D90 comes with this lens.

The focal length of 26mm is 17mm of the same APS-C on the Quan Huafu model, and the focal length of 26mm can be called equivalent focal length, where 26/ 17= 1.5 is the focal length conversion multiple. The concept of frame has been introduced before, and the multiple of photosensitive element size is the conversion multiple of equivalent focal length.

There is a formula when converting equivalent focal length, that is, equivalent focal length = lens focal length x conversion multiple. For example, the effect of APS-C frame camera using 28-70mm lens is equivalent to that of full-frame camera using 42- 105mm lens.

Canon-Understand the relationship among focal length, shooting distance and aperture.

Baidu encyclopedia-focal length