How Does the Cameras Auto Focus?

When the camera focused properly, the details of the image became clear; Images of the lines or the contours of objects become sharp.

When the camera focused very clearly, the details of the image becomes clear. The lines of the images or the contours of the objects become sharp, These details are the high-frequency components of video in the electrology, the clearest the focus is, the largest scale the high-frequency components are.

In accordance with the above thinking, maintain video signal samples of three locations in one image. When high-frequency components of the 3 positions are up to the greatest extent or at least two high-frequency components are to achieve the peak point, stepping motor is stopped, then, focus is at the best status.