What is close-up focusing? Just explain this concept, thank you!

1. Close-up focusing method is aimed at the imperfection of some camera focusing systems. Like I usually use a mechanical machine, the premise of close-up focusing is that you use a zoom lens, assuming it is a 28-70 lens. When you want to take a 28mm wide-angle portrait, you have to take pictures of the scenery and people, with the focus on a person's face. This man is in the middle of the photo. If you hit the 28mm end, the face area of the person in the picture will become very, very small, and it is difficult to observe whether the focus is on the face in the viewfinder. At this time, you can zoom the lens to the 70mm segment, that is, the telephoto end, and focus on the person's face. After really focusing, change the lens back to the 28mm end and shoot again, so as to ensure that the focus is on the person's face. It can also ensure the accuracy of focusing.

I really don't know how to answer you about the principle of automatic aperture.

You can change the aperture size of the lens through the body, which is the automatic aperture. How to use it depends on the photo effect you want. Change the aperture size according to the effect and exposure. For example, if you want people to be clear when shooting, and the distant background is blurred, then turn the aperture up, and turn it down if you want people to be clear from the distant background.