What do you mean by phase focusing and mixed focusing? I am an idiot with photographic knowledge. Ask the great god for a detailed answer

Phase focusing is a three-dimensional focusing system. At present, most of the phase focusing systems are lens-separated phase detection systems. The working principle is to detect where the two beams imaged by the lens meet and judge the direction and distance of defocusing. Therefore, the camera must have a mirror/sub-mirror to reflect the imaging beam to an independent focusing system, which needs a separate lens to image the two beams on two CCD linear arrays respectively. CCD linear array is a scale to measure the convergence of imaging beam. The advantage of the phase focusing principle is that it can control the lens focusing in one step, which is theoretically faster. The disadvantages are complex structure and high cost, and the installation and modulation accuracy of the independent focusing system affect the focusing accuracy.

Contrast focusing is two-dimensional focusing. Its principle is to find the clearest focus position according to the contrast change of the imaging picture when the lens is in focus. Contrast focusing is simple, and no special focusing parts are needed; Taking the final imaging as the detection object is absolutely accurate. The contrast focusing adopts the method of constantly exploring and comparing. At the beginning, you have to gamble to know where the point is. In this process, you can only cross the river by feeling the stones. Before the end, you have to miss the point before you know how to go back and cherish it. Therefore, it is generally considered that contrast focusing is slower than phase focusing.

Hybrid focusing is a kind of focusing method which combines phase focusing and contrast focusing.