How to control the depth of field for beginners of photography

Lead: With the gradual improvement of photography technology, beginners of photography are bound to have higher and higher requirements for pictures? Exquisite This is also a must for a person who likes photography. As the saying goes? Soldiers who don't want to be generals are not good soldiers? Only by being strict with yourself and being proactive can photography technology advance by leaps and bounds. In order to make the shot picture have a qualitative leap, the control of depth of field is a compulsory course. Different depth of field effects will have completely different visual impact on the picture. There are three factors that affect the depth of field: aperture size, focal length and object distance, which are the focus of our study in this section.

Controls the depth of field of the picture.

1. What is the depth of field?

As we all know, cameras can only shoot after focusing. Theoretically, a photo is only clear when it is in focus, and the scenery before and after it is out of focus will be blurred. However, based on the lens, shooting distance and other factors, there will still be a distance before and after focusing, which can clearly show the scene without falling into a blurred area. This clear range is called depth of field.

The application of depth of field is a common expression technique in shooting, which can make the plane picture show a sense of space, thus enhancing the appreciation and expression of the photo.

The focus is on one third of the picture.

The focus of the above picture is located in one third of the picture, because the aperture used is small, and the clear area of the picture from the front to the back of the focus is very extensive, which is called large depth of field. It has been used in landscape photography for a long time.

The focus is on the front petals.

The focus of the above picture is on the front petal, because the aperture used is larger and the clear area before and after the petal is smaller, which is called small depth of field. It is often used in small scenes such as still life photography and portrait photography.

Photos with small depth of field will only be clearly displayed in the focused part, and the places outside the depth of field will be blurred; In a photo with a large depth of field, all the scenes are very clear, and the effects of the two in the picture are completely different.

2. The aperture size can determine the depth of field of the picture.

Aperture size not only determines the exposure, but also has a more important impact on the depth of field. Generally speaking, the smaller the aperture, the greater the depth of field at the same focal length and distance; The larger the aperture, the smaller the depth of field. Usually we use a small aperture to get a large depth of field to show the depth of the scene. When taking landscape photos, small apertures are often used to highlight the theme, showing a clearer and broader sense of space.

Aperture: F2.8 Shutter speed: 1/250s Sensitivity: ISO 100 Focus: 50mm.

The aperture of F2.8 takes a picture with a small depth of field, and the background is blurred, which has a different artistic conception.

When shooting scenery, facing the vast and boundless space, using a small aperture can make the picture clearer. At the same time, low-angle shooting can raise the height of the horizon and make the picture more vivid, three-dimensional and vivid.

3. The focal length can determine the depth of field of the picture.

The depth of field is not only directly related to the aperture size, but also the focal length. With the same shooting distance and aperture size, a shorter focal length can create a greater depth of field, emphasize the characteristics of the surrounding environment and absorb more environmental elements. The depth of field produced by a long focal length is smaller than that produced by a short focal length, so a clearer close-up can be captured.

Aperture: F9 Shutter speed:1160s Sensitivity: ISO 160 Focus: 40mm

The advantage of a short focal length lens is that it has a large depth of field. If it is matched with a small aperture, the depth of field of the picture will be greater. The picture on the left was shot with a lens of 24-105 mm. With the small aperture of F 1 1, the depth of field of the picture is very wide, and the definition is very high whether it is a close-up flower or a distant tree. Using short focal length and large depth of field to emphasize the environment can get realistic picture effects.

Aperture: F9 Shutter speed:1160s Sensitivity: ISO 160 Focus: 40mm

The optical principle of telephoto lens determines that its depth of field is inherently smaller than that of short focal length lens. In the shooting on the left, the telephoto end of the lens is used to zoom in on the main flower cluster, and the trees and grasslands in the background are naturally blurred. The effect of small depth of field makes the main flower cluster more prominent, allowing the audience to focus on the flowers in the flower cluster, thus effectively highlighting the details.

Short focal length usually refers to a wide-angle lens, because the wide-angle lens has a very large viewing angle, which is very suitable for shooting pictures with rich scenes. The best effect is to make such scenes as clear as possible. Therefore, short focal length is usually combined with small aperture shooting to obtain a large depth of field picture effect.

4. The distance from the subject can determine the depth of field of the picture.

The last factor that affects the depth of field is the distance from the subject. Shooting distance, also called object distance, refers to the distance from the focus to the lens, not anything in front of the lens, because a clear area can only be formed before and after the focus.

The influence of object distance on depth of field is as follows: when the focal length and aperture are fixed, the depth of field is smaller when the scene is close to the lens; When the scene is far away from the lens, the depth of field is larger. The reason is that the size of the image is determined by the distance of the object. When the distance of the scene is close, the imaging increases and the dispersion circle becomes thicker, so the smaller the object distance, the shallower the depth of field. With the increase of distance, the depth of field gradually increases.

Compared with the above picture, you will find that not only the flowers are clear, but almost the whole flower container is clear, and even the stone decoration below is no longer blurred. The purpose of this kind of shooting is to show the relationship between flowers, utensils and background, so as to shape the overall sweet and light style of the picture.

Aperture: F4 Shutter speed: 1/200s Sensitivity: ISO250 Focus: 50mm

Close-range shooting is suitable for the local close-up of the subject, which magnifies a certain feature and leaves a deep impression on the viewer. Long-distance shooting can show more picture details.

Aperture: F4 Shutter speed: 1/200s Sensitivity: ISO250 Focus: 50mm

In actual shooting, we can control the depth of field of the picture by adjusting the aperture size, using a long or short focal length and getting close to or away from the subject.