How to define depth of field in photography

Depth of field refers to the range of the distance between the front and back of an object measured by imaging in front of a camera lens or other imager.

After focusing, the distance between the clear images before and after focusing is called depth of field. There is a certain length of space in front of the lens (before and after focal length adjustment). When the subject is located in this space, its imaging on the negative is just between the two diffusion circles before and after focusing. The length of the space where the subject is located is called the depth of field.

In photography, the depth of field is a crucial concept, which determines the clarity of the background and foreground of the photo, and then affects the atmosphere and expressiveness of the whole picture. Understanding and mastering the principles and skills of depth of field is a basic accomplishment that every photographer must have.

Depth of field refers to the range where everything is clearly visible from the foreground to the background in the shooting scene. The size of this range depends on many factors, including the focal length of the lens, the size of the aperture, shooting distance and so on.

When shooting, if the depth of field is too shallow, the foreground and background may become blurred, and only the subject is clear, which may highlight the theme, but it may make the picture appear monotonous; If the depth of field is too large, it may make the whole picture look clear, but it may lack focus. So photographers need to adjust the depth of field according to their creative intentions and shooting scenes.

There are many factors that affect the depth of field.

The most important thing is the focal length and aperture of the lens. Generally speaking, the longer the focal length, the shallower the depth of field; The larger the aperture, the shallower the depth of field. Therefore, when shooting with a telephoto lens or a large aperture, you need to pay attention to controlling the depth of field to avoid making the picture too blurred.

In addition to focal length and aperture, shooting distance also affects depth of field. Under the same focal length and aperture, the closer the shooting distance, the shallower the depth of field; The farther the shooting distance, the greater the depth of field. Therefore, when shooting close-up objects, it is necessary to control the depth of field to avoid blurring the background.