Principle of continuous focus mode photography

AF-S: Single autofocus Single autofocus focuses only when the shutter is half pressed. This is the most basic focusing method, and the basic steps are: framing, composition, half-pressing the shutter, focusing and shooting. AF-C: continuous autofocus. Continuous autofocus means that the camera always performs focusing operation regardless of whether the shutter is half pressed or not.

2. Different usage scenarios

Use AF-S when shooting static objects, AF-C when shooting moving objects such as birds, and AF-C when shooting sports events.

Extended data:

principle

From the basic principle, autofocus can be divided into two categories: one is ranging autofocus based on the measurement of the distance between the lens and the object being photographed, and the other is focusing detection autofocus based on clear imaging on the focusing screen.

Ranging autofocus mainly includes infrared ranging and ultrasonic ranging.

The principle of infrared ranging method is that the camera actively emits infrared light as the ranging light source, forming the geometric relationship between infrared light-emitting diodes, and then calculating the focusing distance.

The ultrasonic ranging method is based on the ultrasonic propagation time between the digital camera and the object. Digital cameras are equipped with ultrasonic transmitting and receiving devices respectively. When working, the ultrasonic vibration generator emits continuous ultrasonic waves. After the ultrasonic wave reaches the subject, it immediately returns to the receiver for sensing, and then the integrated circuit calculates and determines the focusing distance according to the round-trip time of the ultrasonic wave.

Infrared autofocus and ultrasonic autofocus use active light or sound waves to measure distance, which is called active autofocus.