What is the meaning and purpose of focusing?

Triangular composition refers to the horizontal division of the picture into three parts, and each sub-center can be put together with the main form, which is suitable for the main body with multi-form parallel focus. It can also represent large space, small objects, and vice versa. This composition is vivid and concise. Three-point method can be used to illustrate different scenes such as close range.

When observing the scenery through the viewfinder, imagine dividing the picture into three equal parts. The intersection of lines is the place where the interesting center and other minor scenery are arranged. Of course, this rule can be used flexibly, and the center of interest does not have to be exactly at the intersection, but it should also be roughly in that area. Those intersections at the right end of the picture are usually considered to be the strongest; Of course, the left third is sometimes used to arrange interesting centers, depending on how the picture is balanced. Trigonometry applies to horizontal and vertical frames. Arrange the subject and partner according to the three-point method, and the photos will be compact and powerful.

The chart is as follows:

The latter two questions are too huge. Recommend "New York Institute of Photography Course". Baidu Library has e-books to download.