How to choose the best focusing mode

First, how to choose the correct focusing method according to the scene

Automatic area focusing: the most suitable focusing mode for snapshots

In automatic area focusing mode, the camera will check all the focused objects and choose the point closest to the focus, which is very suitable for snapshot, such as street shooting. Some cameras can also automatically identify people in the scene in this mode and give them priority focus. This mode is actually very suitable for beginners of photography. However, just like other automatic systems, automatic area focusing is sometimes not so brilliant, and occasionally there will be misalignment.

5 1 point single focus: suitable for high-precision focusing.

In the single focus mode, the focus position can be selected according to the shooting requirements, giving users full freedom of choice. Single focus is more suitable for static objects, in other words, single focus is more suitable for shooting scenery, still life and other subjects.

1 1 single focus: suitable for daily shooting.

It is also a single focus, but the number of focuses here has dropped sharply to 1 1. Does that mean that the focusing performance is degraded? Of course not. The more the focus, the better. It's just that it's used less in daily life. Too much switching will waste a lot of time. At this time, the advantages of 1 1 point single-point focusing mode are reflected: under the condition of ensuring the same focusing area and accuracy, the focus switching time is shortened.

9-point dynamic area focusing: suitable for shooting even and slow moving objects.

The 9-point dynamic area focusing mode is more suitable for shooting objects moving slowly at a constant speed, such as running and trains. As long as the object is in these nine focus areas, the camera will adjust the focus position in real time according to the movement of the object.

2 1 point dynamic area focusing: suitable for shooting irregular moving objects.

The principle of 2 1 point dynamic area focusing is not much different from 9: 00, except that it covers a wider area and is suitable for shooting irregular moving objects (such as children and animals) to cope with emergencies.

5 1 point dynamic area focusing: suitable for tracking and focusing the subject.

The camera will use all the focal points to track and predict the subject. At this time, as long as the subject is in the picture, the photographer can realize real-time focusing. Automatic area focusing and dynamic area focusing look very similar, but in fact they are very different. In the automatic area focus mode, all focus choices are automatically completed by the camera, and there is no human factor; In the dynamic area focusing mode, the user can set the initial focusing point, which is equivalent to telling the camera where to start focusing and what color the subject is, thus improving the success rate of tracking and focusing.

Second, the focus mode

Auto focus:

Traditional cameras use a similar visual ranging method to achieve autofocus. The camera emits an infrared ray (or other rays), determines the distance of the subject according to the reflection of the subject, and then adjusts the lens combination according to the measurement result to realize automatic focusing. This automatic focusing method-direct, fast, easy to realize and low cost-sometimes makes mistakes (when there is something else between the camera and the subject, such as glass, or the light is insufficient, automatic focusing cannot be realized), and the accuracy is poor. Today's high-end cameras generally don't use this method. Because the camera actively emits rays, it is called active, and because it is actually only ranging, it is also called non-TTL because it does not judge whether coking is correct through the actual imaging of the lens. Compared with active autofocus, passive autofocus was developed later, that is, judging whether coking is correct according to the actual imaging of the lens. The basis of judgment is generally contrast detection, and the specific principle is quite complicated. Because this method is realized by lens imaging, it is called TTL autofocus. It is precisely because this autofocus method is based on lens imaging, which has high focusing accuracy and low error rate, but the technology is complex, the speed is slow (except for the advanced autofocus lens using ultrasonic motor) and the cost is high.

Manual focusing:

Manual focusing, that is, manually turning the focusing ring to adjust the camera lens, so as to make the captured photos clear, largely depends on the judgment of the human eye on the image on the focusing screen, the photographer's proficiency and even the photographer's vision. Early SLR cameras and paraxial cameras basically used manual focusing to complete the focusing operation. Now quasi-professional and professional digital cameras, as well as SLR digital cameras, are equipped with manual focusing function to meet different shooting needs. Focusing is equivalent to focusing, that is, changing the image distance v and satisfying the imaging formula1/u+1/v =1/f, thus forming a clear image on the negative. Zooming is to change the focal length of the lens, that is, to change the viewing angle of the lens. Its principle is to add a family of movable lenses to the lenses of the lens; Focusing is to adjust the authenticity of the image, that is, to change the distance between the lens and the imaging surface, so as to make the image clear. Both nouns have a focus word with completely different meanings.

Multi-focus:

Many digital cameras have multi-focus function or area focus function. When the focus center is not set in the center of the picture, multi-point focus or multiple focus can be used. In addition to setting the focus position, you can also set the focus range, allowing users to take photos with different effects. Common multi-point focusing includes 5: 00, 7: 00 and 9: 00.

Holographic autofocus:

Holographic AF is a unique function of Sony digital camera and a brand-new autofocus optical system. It uses advanced laser holography technology to detect the edge of the object by laser spot. Even in the dark environment, it can take photos with precise focus, and the effective shooting distance is 4.5 meters.