Many photographers are often neglected the importance of focusing when taking pictures, that as long as the autofocus to shoot a clear picture, the result is actually found in the film after a lot of photos in fact the focus is vague; to investigate the reason is the photographer's Understand the camera made by the focusing machine. Therefore, this chapter will give you a complete description of the correct focus on the concept of focus in any shooting situation can be completed successfully.

Camera focus mode

DSLR has two focus modes, respectively
AF autofocus
MF manual focus
Now let's take a look at the characteristics of the two focus modes.

First, AF autofocus
AF (Automatic Focus) basically uses the two sets of "image sensor" below the mirror to detect the contrast of light and shade and the color contrast from the subject; the action mode is to fix the lens in front of one of the sensors , Only move the lens of another group of sensors so that the signals sensed by the two groups of sensors can be discriminated. If the two are the same, it indicates the correct focus, and if there is a difference, the variation of the lens should be calculated from the difference and then Adjust the lens position, in order to complete the autofocus work.

Autofocus operation
To make the camera autofocus, you only need to press the shutter halfway, the camera's shutter button is generally adopted two-stage design, the first paragraph is responsible for the camera autofocus function, paragraph 2 officially opened the shutter to shoot. However, half-press the shutter AF, remember to pay attention to the viewing window "focus indicator" display, if the focus indicator light is steady, the camera focus is completed, you can continue to press the shutter button to shoot; otherwise, if the focus indicator Not displayed or blinking, it means the camera can not focus properly, this time you must move the lens or change the focus point to re-select the focus position, or even press the shutter camera can not shoot.

Note: The general beginner photographer autofocus, the shutter button will be pressed directly, but this body position is often in the middle of the screen, the relative appears to be too dull; so, when the completion of the autofocus work, well maintained half Press the shutter button and move the lens to find a better composition before shooting.

Autofocus mode
In order to make AF effective in various occasions, manufacturers have to join many models for autofocus, it is common to the following three kinds:

(1), One Shot (One Shot):
This is the default AF mode, as long as the photographer half-press the shutter to complete the focus, it will no longer any focus action, suitable for shooting will not move the static body.

(2), Continuous AF (AI Servo):
The subject photographed by the photographer belongs to the mobile form, you must use the continuous autofocus mode. With this mode, you only need to press the shutter button halfway and aim at the moving subject, then the camera focuses continuously until the desired image is captured by pressing the shutter button.

(3), AI Focus (AI Focus):
This mode of action, at the beginning of the body half-press the shutter when the single-time autofocus, during which if the main body began to move, the camera automatically switches to continuous autofocus. For example, the athlete who shoots a running start line is initially in a quiescent state, but after starting, it becomes a moving subject. In this case, the smart autofocus mode must be used in order to "rest the body that will move again" Focus.

Second, MF manual focus
As technology advances, the camera's autofocus system is already quite established and well-recognized by professional photographers; however, under certain circumstances, there is still a need to use "MF (Manual Focus) - Manual Focusing" such as the following:
1. Contrast low body, such as cloudless blue sky, monochrome walls.
2. Lack of light situation.
3. The subject is under the backlight or itself is a luminous body.
Overlapping objects, such as animals in cages.

Switch MF-manual focus
When the autofocus fails, we have to switch the focus mode to manual, and the mode of switching varies depending on the type of camera. The Canon system is designed on the lens while the Nikon is on the camera body or lens Design of the focus switch.

Hand on the dynamic focus

Manual Focusing is done by adjusting the focus ring on the lens, so before using it you have to know the direction the lens focus ring is turning, the closer you are to the left, the closer the camera is to the camera, or the closer you turn to the camera. To confirm this mechanism The reason is that for manual focus, you can judge the position of the subject immediately after the focus ring turn left or right, so as to reduce the time to rotate the focus ring back and forth to enhance the manual focus speed. For photographers, the accumulation of this experience helps to capture the dynamic subject.

Brightness adjustment
Since manual focus is determined by the clarity of the image in the viewfinder to see if the focus is correct, you must make sure that the adjustment of the "dystonia" is correct before manual focusing. The so-called bowing brightness adjustment is based on each person's vision of different visual acuity, the optical adjustment mechanism, you have to adjust according to personal vision, so that they can clearly see the scene inside the viewfinder, so manual focus, to ensure that Look at the picture is clear, and then press the shutter to shoot.