The difference between mechanical focusing and electronic focusing

Focusing is used to clearly image people or objects. Mechanical adjustment can also be said to be manual adjustment of the lens to make the image clear, while electronic focusing is to automatically control the lens through automatic devices on cameras such as photoelectric detection, infrared detection and ultrasonic detection to make the image clear!

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Manual focusing: a new focusing method. Before autofocus AF technology appeared, MF (Manual Focusing MF) technology was the absolute mainstream. Even with the popularity of AF technology today, most cameras still retain the manual focusing function, which shows its importance.

Manual focus is characterized by manually turning the focus ring on the lens (some digital cameras use buttons to adjust the distance) and adjusting the position of the lens to achieve accurate focus. Its advantage lies in controllability, and it is very useful in some occasions. But its shortcomings are also obvious: first, the speed is slow, and the method of manually rotating the focus ring is stretched in some occasions; Secondly, in dim light, it is difficult for human eyes to see the scenery in the lens, which will also increase the difficulty of accurate focusing; When the photographer's eyesight is poor and he doesn't wear his eyes at the same time, it is difficult to achieve the focusing accuracy of 100%.

Auto focus: In order to overcome the shortcomings of manual focus, auto focus technology was born. It turns out that when the camera is aimed at an object, the focusing system will automatically measure its distance and automatically adjust the lens to achieve accurate focusing. There are two main types of autofocus technology:

Active auto-focusing: the camera emits an infrared ray or ultrasonic wave along a straight line to the photographed object, and then the sensor on the camera calculates the distance between the camera and the photographed object according to the reflected infrared ray or ultrasonic wave, and then controls the focusing motor to move the lens to realize accurate focusing. This focusing method is difficult to focus on objects with high brightness, long distance and smooth surface, which can absorb light and waves, because the emitted light and waves cannot be reflected back to the camera correctly.

Passive autofocus: the way that the camera directly receives the reflection of the object itself to judge the distance and carry out autofocus. The advantages of this focusing method are: no need to emit light and waves, reduce energy consumption, and focus accurately under good light conditions. The disadvantage is that it is difficult to focus on objects with thin lines. It is worth mentioning that this focusing method can't perform well even in poor light. In order to overcome this weakness, people have designed an autofocus auxiliary lamp on the camera to illuminate the subject to help focus.